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Damiano Magri - One of the best experts on this subject based on the ideXlab platform.
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Transcranial direct current stimulation improves the QT Variability index and autonomic cardiac control in healthy subjects older than 60 years.
Clinical interventions in aging, 2016Co-Authors: Gianfranco Piccirillo, Federica Moscucci, Cristina Ottaviani, Claudia Fiorucci, Nicola Petrocchi, Claudia Di Iorio, Fabiola Mastropietri, Ilaria Parrotta, Matteo Pascucci, Damiano MagriAbstract:BACKGROUND Noninvasive brain stimulation technique is an interesting tool to investigate the causal relation between cortical functioning and autonomic nervous system (ANS) responses. OBJECTIVE The objective of this report is to evaluate whether anodal transcranial direct current stimulation (tDCS) over the temporal cortex influences short-period temporal ventricular repolarization dispersion and cardiovascular ANS control in elderly subjects. SUBJECTS AND METHODS In 50 healthy subjects (29 subjects younger than 60 years and 21 subjects older than 60 years) matched for gender, short-period RR and systolic blood pressure spectral Variability, QT Variability index (QTVI), and noninvasive hemodynamic data were obtained during anodal tDCS or sham stimulation. RESULTS In the older group, the QTVI, low-frequency (LF) power expressed in normalized units, the ratio between LF and high-frequency (HF) power, and systemic peripheral resistances decreased, whereas HF power expressed in normalized units and α HF power increased during the active compared to the sham condition (P
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Transcranial direct current stimulation improves the QT Variability index and autonomic cardiac control in healthy subjects older than 60 years
Clinical Interventions in Aging, 2016Co-Authors: Gianfranco Piccirillo, Federica Moscucci, Cristina Ottaviani, Claudia Fiorucci, Nicola Petrocchi, Claudia Di Iorio, Fabiola Mastropietri, Ilaria Parrotta, Matteo Pascucci, Damiano MagriAbstract:Background: Noninvasive brain stimulation technique is an interesting tool to investigate the causal relation between cortical functioning and autonomic nervous system (ANS) responses.\ud Objective: The objective of this report is to evaluate whether anodal transcranial direct current stimulation (tDCS) over the temporal cortex influences short-period temporal ventricular repolarization dispersion and cardiovascular ANS control in elderly subjects.\ud Subjects and methods: In 50 healthy subjects (29 subjects younger than 60 years and 21 subjects older than 60 years) matched for gender, short-period RR and systolic blood pressure spectral Variability, QT Variability index (QTVI), and noninvasive hemodynamic data were obtained during anodal tDCS or sham stimulation.\ud Results: In the older group, the QTVI, low-frequency (LF) power expressed in normalized units, the ratio between LF and high-frequency (HF) power, and systemic peripheral resistances decreased, whereas HF power expressed in normalized units and α HF power increased during the active compared to the sham condition (P,0.05).\ud Conclusion: In healthy subjects older than 60 years, tDCS elicits cardiovascular and autonomic changes. Particularly, it improves temporal ventricular repolarization dispersion, reduces sinus sympathetic activity and systemic peripheral resistance, and increases vagal sinus activity and baroreflex sensitivity
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Il QT Variability Index come strumento per la stratificazione del rischio di morte improvvisa
Recenti progressi in medicina, 2014Co-Authors: Gianfranco Piccirillo, Federica Moscucci, Damiano MagriAbstract:Sudden cardiac death is the leading cause of mortality in patients with chronic heart failure (CHF) and history of myocardial infarction. Selection of patients at risk of sudden cardiac death is dramatically important to choose the correct therapeutic approach. The QT Variability Index (QTVI) is a non-invasive measure of repolarization lability that has been applied to a wide variety of subjects with cardiovascular disease. It is a ratio of normalized QT Variability to normalized heart rate Variability, and therefore includes an assessment of the autonomic nervous system tone. As opposed to T wave alternans, QTVI assesses variance in repolarization at all frequencies. Recent studies suggest that QTVI may help clinicians choosing the appropriate implantable cardiovester defibrillator timing implantation, in patients with dilated or hypertrophic cardiomyopathy or CHF because of its efficacy in patient evaluation and follow-up.
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Effect of Acute Mental Stress on Heart Rate and QT Variability in Postmyocardial Infarction Patients
ISRN cardiology, 2012Co-Authors: Damiano Magri, Gianfranco Piccirillo, Raffaele Quaglione, Annalaura Dell’armi, Marilena Mitra, Stefania Velitti, Daniele Di Barba, Andrea Lizio, Damiana Maisto, Francesco BarillàAbstract:Emotionally charged events are associated with an increased risk of sudden cardiac death (SCD). In this study we assessed RR and QT Variability index (QTVI) at baseline during anger recall test (AR). We calculated QTVI from a 5-min ECG recording and from a 10-beats segment around the presumed maximum sympathetic activation in thirty post-myocardial infarction patients under β-blocker therapy and 10 controls underwent. In all groups, the low-frequency component of RR and SBP increased during AR. In all recordings, the QTVI calculated on a 5-min ECG recording and the QTVI10 beats were higher in patients than in controls (P < 0.05). The QTVI during AR remained unchanged from baseline within each group. Conversely, during AR, the QTVI10 beats in controlsdiminishedsignificantly(P
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effect of acute mental stress on heart rate and QT Variability in postmyocardial infarction patients
International Scholarly Research Notices, 2012Co-Authors: Damiano Magri, Gianfranco Piccirillo, Raffaele Quaglione, Marilena Mitra, Stefania Velitti, Daniele Di Barba, Andrea Lizio, Damiana Maisto, Annalaura Dellarmi, Francesco BarillàAbstract:Emotionally charged events are associated with an increased risk of sudden cardiac death (SCD). In this study we assessed RR and QT Variability index (QTVI) at baseline during anger recall test (AR). We calculated QTVI from a 5-min ECG recording and from a 10-beats segment around the presumed maximum sympathetic activation in thirty post-myocardial infarction patients under β-blocker therapy and 10 controls underwent. In all groups, the low-frequency component of RR and SBP increased during AR. In all recordings, the QTVI calculated on a 5-min ECG recording and the QTVI10 beats were higher in patients than in controls (P < 0.05). The QTVI during AR remained unchanged from baseline within each group. Conversely, during AR, the QTVI10 beats in controlsdiminishedsignificantly(P <0.05)frombaselinewhereasinpatientsremainedunchanged.Theinabilitytobufferanacute stress-induced increase in sympathetic activity could explain why events charged with acute stress are associated with an increased risk of ventricular arrhythmias in this setting of patients and support the role of cognitive behavior stress management strategies.
V.k. Yeragani - One of the best experts on this subject based on the ideXlab platform.
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Cardiac autonomic function and vascular profile in subclinical hypothyroidism: Increased beat-to-beat QT Variability.
Indian journal of endocrinology and metabolism, 2016Co-Authors: Pramila Kalra, V.k. Yeragani, Km Prasanna KumarAbstract:Background: Patients with subclinical hypothyroidism (SH) may have higher incidence of coronary heart disease and autonomic dysfunction. Design of the Study: Prospective case control study. Aim and Objectives: To evaluate beat-to-beat QT Variability and vascular stiffness in patients with SH compared to normal controls. Materials and Methods: We compared linear and nonlinear measures of cardiac repolarization liability using beat-to-beat QT intervals derived from the surface electrocardiogram during supine posture and vascular indices including pulse wave velocity and ankle-brachial index (ABI) during supine posture between female patients with SH and age- and sex-matched normal controls. Spectral analysis was done at very low frequency (LF) (0.003-0.04 Hz), Low frequency (LF) (0.04-0.15 Hz), and high frequency (HF) (0.15-0.4 Hz). The HF represents vagal regulation (parasympathetic) and LF represents both parasympathetic and sympathetic regulation. Results: We recruited 58 women with a mean age of 31.83 ± 8.9 years and 49 controls with mean age of 32.4 ± 9.9 years ( P = NS). QT Variability index (QTvi) was higher in cases compared to controls ( P = 0.01). The ratio of LF/HF of R-R interval which is an index of sympathovagal tone was significantly more in cases compared to controls ( P = 0.02). The difference in the left minus the right ABI was significant between cases and controls ( P = 0.03). Conclusions: The cases had lower parasympathetic activity as compared to controls, and there was a predominance of sympathetic activity in cases. QTvi may be an important noninvasive tool in this group of patients to study the risk of cardiovascular mortality.
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Heart rate Variability, QT Variability, and electrodermal activity during exercise.
Medicine and science in sports and exercise, 2010Co-Authors: Silke Boettger, V.k. Yeragani, Christian Puta, Lars Donath, Hans-josef Müller, Holger H. W. Gabriel, Karl-jürgen BärAbstract:BOETTGER, S., C. PUTA, V. K. YERAGANI, L. DONATH, H.-J. MULLER, H. H. W. GABRIEL, and K.-J. BAR. Heart Rate Variability, QT Variability, and Electrodermal Activity during Exercise. Med. Sci. Sports Exerc., Vol. 42, No. 3, pp. 443-448, 2010. Purpose: Various measures of autonomic function have been developed, and their applicability and significance during exercise are controversial. Methods: Physiological data were therefore obtained from 23 sport students before, during, and after exercise. Measures of R-R interval Variability, QT Variability index (QTvi), and electrodermal activity (EDA) were calculated. We applied an incremental protocol applying 70%, 85%, 100%, and 110% of the individual anaerobic threshold for standardized comparison. Results: Although HR increased stepwise, parasympathetic parameters such as the root mean square of successive differences were not different during exercise and do not mirror autonomic function satisfactorily. Similar results were observed with the approximate entropy of R-R intervals (ApEnRR). In contrast, the increase in sympathetic activity was well reflected in the EDA, QTvi, and ApEn of the QT interval (ApEnQT)/ApEnRR ratio. Conclusion: We suggest that linear and nonlinear parameters of R-R Variability do not adequately
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Increased QT Variability in patients with anorexia nervosa--an indicator for increased cardiac mortality?
The International journal of eating disorders, 2009Co-Authors: Mandy Koschke, V.k. Yeragani, Michael Karl Boettger, Claudia Macholdt, Steffen Schulz, Andreas Voss, Karl-jürgen BärAbstract:Objective Increased mortality in anorexia nervosa is associated with autonomic dysfunction and prolongation of the QT interval. In this study, we examined the relative importance of repolarization abnormalities and vagal modulation of heart rate. In particular, we hypothesized that patients with anorexia nervosa show increased QT interval Variability, particularly since this measure has been shown to correlate with serious cardiac arrhythmias. Method We assessed linear and nonlinear heart rate Variability (HRV) parameters as well as measures of QT Variability in 20 female patients with anorexia nervosa and 20 controls. In patients, parameters were correlated with serum electrolytes. Results QT Variability was significantly increased in the patient group and correlated negatively with serum potassium concentrations. HRV measures showed a shift of autonomic balance towards vagal predominance. Discussion The increase in QT Variability might at least in part account for the higher risk of cardiac arrhythmias in patients with anorexia nervosa. Once validated in a prospective study design, parameters of QT Variability might serve as surrogate markers for arrhythmia risk stratification in anorexia nervosa. Supplementation with potassium might normalize QT Variability abnormalities. © 2009 by Wiley Periodicals, Inc. Int J Eat Disord 2010; 43:743–750
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Influence of olanzapine on QT Variability and complexity measures of heart rate in patients with schizophrenia.
Journal of clinical psychopharmacology, 2008Co-Authors: Karl-jürgen Bär, Mandy Koschke, Steffen Schulz, Andreas Voss, Sandy Berger, Manuel Tancer, V.k. YeraganiAbstract:Previous studies have shown that untreated patients with acute schizophrenia present with reduced heart rate Variability and complexity as well as increased QT Variability. This autonomic dysregulation might contribute to increased cardiac morbidity and mortality in these patients. However, the additional effects of newer antipsychotics on autonomic dysfunction have not been investigated, applying these new cardiac parameters to gain information about the regulation at sinus node level as well as the susceptibility to arrhythmias. We have investigated 15 patients with acute schizophrenia before and after established olanzapine treatment and compared them with matched controls. New nonlinear parameters (approximate entropy, compression entropy, fractal dimension) of heart rate Variability and also the QT-Variability index were calculated. In accordance with previous results, we have observed reduced complexity of heart rate regulation in untreated patients. Furthermore, the QT-Variability index was significantly increased in unmedicated patients, indicating increased repolarization lability. Reduction of the heart rate regulation complexity after olanzapine treatment was seen, as measured by compression entropy of heart rate. No change in QT Variability was observed after treatment. This study shows that unmedicated patients with acute schizophrenia experience autonomic dysfunction. Olanzapine treatment seems to have very little additional impact in regard to the QT Variability. However, the decrease in heart rate complexity after olanzapine treatment suggests decreased cardiac vagal function, which may increase the risk for cardiac mortality. Further studies are warranted to gain more insight into cardiac regulation in schizophrenia and the effect of novel antipsychotics.
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Acute psychosis leads to increased QT Variability in patients suffering from schizophrenia.
Schizophrenia research, 2007Co-Authors: Karl-jürgen Bär, Mandy Koschke, Michael Karl Boettger, Andreas Voss, Sandy Berger, Alexander Kabisch, Heinrich Sauer, V.k. YeraganiAbstract:Patients with schizophrenia have been reported to experience sudden cardiac death 3 times more likely than individuals from the general population. One important factor related to an increased risk of cardiac arrhythmias and sudden death is the prolongation of the QTc interval. This study examined whether acute psychosis might influence the beat-to-beat Variability of the QT interval, which reflects effectively cardiac repolarization lability. High resolution electrocardiographic recordings were performed in 25 unmedicated patients suffering from acute schizophrenia and matched controls. From these, parameters of beat-to-beat heart rate and QT Variability measures such as approximate entropy and QT Variability index (QTvi) were calculated. Measures were correlated with the scale for the assessment of positive symptoms (SAPS) and negative symptoms (SANS). QTvi was significantly higher in patients with schizophrenia compared to controls. While QTvi correlated with the degree of delusions and hallucinations, no correlation with electrolyte concentrations was found. Approximate entropy of heart rate was decreased indicating reduced complexity and decreased vagal tone. In conclusion, increased QT Variability in patients with schizophrenia indicates abnormal cardiac repolarization lability, which can result in serious cardiac arrhythmias. The correlation of positive symptoms with QT Variability might indicate high sympathetic cardiac activity in these patients, which might be associated with increased cardiovascular mortality.
Gianfranco Piccirillo - One of the best experts on this subject based on the ideXlab platform.
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Transcranial direct current stimulation improves the QT Variability index and autonomic cardiac control in healthy subjects older than 60 years.
Clinical interventions in aging, 2016Co-Authors: Gianfranco Piccirillo, Federica Moscucci, Cristina Ottaviani, Claudia Fiorucci, Nicola Petrocchi, Claudia Di Iorio, Fabiola Mastropietri, Ilaria Parrotta, Matteo Pascucci, Damiano MagriAbstract:BACKGROUND Noninvasive brain stimulation technique is an interesting tool to investigate the causal relation between cortical functioning and autonomic nervous system (ANS) responses. OBJECTIVE The objective of this report is to evaluate whether anodal transcranial direct current stimulation (tDCS) over the temporal cortex influences short-period temporal ventricular repolarization dispersion and cardiovascular ANS control in elderly subjects. SUBJECTS AND METHODS In 50 healthy subjects (29 subjects younger than 60 years and 21 subjects older than 60 years) matched for gender, short-period RR and systolic blood pressure spectral Variability, QT Variability index (QTVI), and noninvasive hemodynamic data were obtained during anodal tDCS or sham stimulation. RESULTS In the older group, the QTVI, low-frequency (LF) power expressed in normalized units, the ratio between LF and high-frequency (HF) power, and systemic peripheral resistances decreased, whereas HF power expressed in normalized units and α HF power increased during the active compared to the sham condition (P
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Transcranial direct current stimulation improves the QT Variability index and autonomic cardiac control in healthy subjects older than 60 years
Clinical Interventions in Aging, 2016Co-Authors: Gianfranco Piccirillo, Federica Moscucci, Cristina Ottaviani, Claudia Fiorucci, Nicola Petrocchi, Claudia Di Iorio, Fabiola Mastropietri, Ilaria Parrotta, Matteo Pascucci, Damiano MagriAbstract:Background: Noninvasive brain stimulation technique is an interesting tool to investigate the causal relation between cortical functioning and autonomic nervous system (ANS) responses.\ud Objective: The objective of this report is to evaluate whether anodal transcranial direct current stimulation (tDCS) over the temporal cortex influences short-period temporal ventricular repolarization dispersion and cardiovascular ANS control in elderly subjects.\ud Subjects and methods: In 50 healthy subjects (29 subjects younger than 60 years and 21 subjects older than 60 years) matched for gender, short-period RR and systolic blood pressure spectral Variability, QT Variability index (QTVI), and noninvasive hemodynamic data were obtained during anodal tDCS or sham stimulation.\ud Results: In the older group, the QTVI, low-frequency (LF) power expressed in normalized units, the ratio between LF and high-frequency (HF) power, and systemic peripheral resistances decreased, whereas HF power expressed in normalized units and α HF power increased during the active compared to the sham condition (P,0.05).\ud Conclusion: In healthy subjects older than 60 years, tDCS elicits cardiovascular and autonomic changes. Particularly, it improves temporal ventricular repolarization dispersion, reduces sinus sympathetic activity and systemic peripheral resistance, and increases vagal sinus activity and baroreflex sensitivity
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Il QT Variability Index come strumento per la stratificazione del rischio di morte improvvisa
Recenti progressi in medicina, 2014Co-Authors: Gianfranco Piccirillo, Federica Moscucci, Damiano MagriAbstract:Sudden cardiac death is the leading cause of mortality in patients with chronic heart failure (CHF) and history of myocardial infarction. Selection of patients at risk of sudden cardiac death is dramatically important to choose the correct therapeutic approach. The QT Variability Index (QTVI) is a non-invasive measure of repolarization lability that has been applied to a wide variety of subjects with cardiovascular disease. It is a ratio of normalized QT Variability to normalized heart rate Variability, and therefore includes an assessment of the autonomic nervous system tone. As opposed to T wave alternans, QTVI assesses variance in repolarization at all frequencies. Recent studies suggest that QTVI may help clinicians choosing the appropriate implantable cardiovester defibrillator timing implantation, in patients with dilated or hypertrophic cardiomyopathy or CHF because of its efficacy in patient evaluation and follow-up.
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Effect of Acute Mental Stress on Heart Rate and QT Variability in Postmyocardial Infarction Patients
ISRN cardiology, 2012Co-Authors: Damiano Magri, Gianfranco Piccirillo, Raffaele Quaglione, Annalaura Dell’armi, Marilena Mitra, Stefania Velitti, Daniele Di Barba, Andrea Lizio, Damiana Maisto, Francesco BarillàAbstract:Emotionally charged events are associated with an increased risk of sudden cardiac death (SCD). In this study we assessed RR and QT Variability index (QTVI) at baseline during anger recall test (AR). We calculated QTVI from a 5-min ECG recording and from a 10-beats segment around the presumed maximum sympathetic activation in thirty post-myocardial infarction patients under β-blocker therapy and 10 controls underwent. In all groups, the low-frequency component of RR and SBP increased during AR. In all recordings, the QTVI calculated on a 5-min ECG recording and the QTVI10 beats were higher in patients than in controls (P < 0.05). The QTVI during AR remained unchanged from baseline within each group. Conversely, during AR, the QTVI10 beats in controlsdiminishedsignificantly(P
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effect of acute mental stress on heart rate and QT Variability in postmyocardial infarction patients
International Scholarly Research Notices, 2012Co-Authors: Damiano Magri, Gianfranco Piccirillo, Raffaele Quaglione, Marilena Mitra, Stefania Velitti, Daniele Di Barba, Andrea Lizio, Damiana Maisto, Annalaura Dellarmi, Francesco BarillàAbstract:Emotionally charged events are associated with an increased risk of sudden cardiac death (SCD). In this study we assessed RR and QT Variability index (QTVI) at baseline during anger recall test (AR). We calculated QTVI from a 5-min ECG recording and from a 10-beats segment around the presumed maximum sympathetic activation in thirty post-myocardial infarction patients under β-blocker therapy and 10 controls underwent. In all groups, the low-frequency component of RR and SBP increased during AR. In all recordings, the QTVI calculated on a 5-min ECG recording and the QTVI10 beats were higher in patients than in controls (P < 0.05). The QTVI during AR remained unchanged from baseline within each group. Conversely, during AR, the QTVI10 beats in controlsdiminishedsignificantly(P <0.05)frombaselinewhereasinpatientsremainedunchanged.Theinabilitytobufferanacute stress-induced increase in sympathetic activity could explain why events charged with acute stress are associated with an increased risk of ventricular arrhythmias in this setting of patients and support the role of cognitive behavior stress management strategies.
Larisa G. Tereshchenko - One of the best experts on this subject based on the ideXlab platform.
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QT Variability and QRST integral
Sex and Cardiac Electrophysiology, 2020Co-Authors: Larisa G. TereshchenkoAbstract:Abstract This chapter reviews sex differences in QT Variability and QRST integral. QT Variability reflects temporal heterogeneity of global electrophysiological substrate, whereas QRST integral describes spatial global electrical heterogeneity (GEH). In spite of more than 30 years of research in GEH, very few studies focused on sex differences in spatial and temporal GEH. Knowledge of sex differences in QT Variability and QRST integral is necessary for appropriate determination of sex-specific threshold of abnormal values. Moreover, the question whether sex modifies association of QT Variability with clinically important outcomes (sudden cardiac death, ventricular tachyarrhythmias) remains largely unanswered. Answering a question of effect modification by sex is necessary for determination of whether risk stratification of sudden cardiac death (or other clinically important outcome) should be sex-specific, or it is enough to define sex-specific thresholds for abnormal electrocardiogram metrics. This chapter reviews available data and highlights knowledge gaps, for consideration in future research.
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repolarization lability measured on 10 second ecg by spatial tt angle reproducibility and agreement with QT Variability
Journal of Electrocardiology, 2014Co-Authors: Albert Feeny, Larisa G. Tereshchenko, Lichy HanAbstract:Abstract Background Reproducibility of spatial TT′ angle on the 10-second ECG and its agreement with QT Variability has not been previously studied. Methods We analyzed 2 randomly selected 10-second segments within 3-minute resting orthogonal ECG in 172 healthy IDEAL study participants (age 38.1 ± 15.2 years, 50% male, 94% white). Repolarization lability was measured by the QT variance (QTV), short-term QT Variability (STV(QT)), and spatial TT′ angle. Bland–Altman analysis was used to assess the agreement between different log-transformed metrics of repolarization lability, and to assess the reproducibility. Results The heart rate showed a very high reproducibility (bias 0.14%, Lin's rho_c = 0.99). As expected, noise suppression by averaging improves reproducibility. Agreement between two 10-second LogQTV was poor (bias − 0.04; 95% limits of agreement [− 1.89; 1.81]), while LogSTV(QT) (0.04 [− 1.01; 1.10]), and especially LogTT′ angle (− 0.009 [− 0.84; 0.82]) was better. Conclusion TT′ angle is a satisfactory reproducible metric of repolarization lability on the 10-second ECG.
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Repolarization lability measured on 10-second ECG by spatial TT′ angle: Reproducibility and agreement with QT Variability
Journal of electrocardiology, 2014Co-Authors: Albert Feeny, Lichy Han, Larisa G. TereshchenkoAbstract:Abstract Background Reproducibility of spatial TT′ angle on the 10-second ECG and its agreement with QT Variability has not been previously studied. Methods We analyzed 2 randomly selected 10-second segments within 3-minute resting orthogonal ECG in 172 healthy IDEAL study participants (age 38.1 ± 15.2 years, 50% male, 94% white). Repolarization lability was measured by the QT variance (QTV), short-term QT Variability (STV(QT)), and spatial TT′ angle. Bland–Altman analysis was used to assess the agreement between different log-transformed metrics of repolarization lability, and to assess the reproducibility. Results The heart rate showed a very high reproducibility (bias 0.14%, Lin's rho_c = 0.99). As expected, noise suppression by averaging improves reproducibility. Agreement between two 10-second LogQTV was poor (bias − 0.04; 95% limits of agreement [− 1.89; 1.81]), while LogSTV(QT) (0.04 [− 1.01; 1.10]), and especially LogTT′ angle (− 0.009 [− 0.84; 0.82]) was better. Conclusion TT′ angle is a satisfactory reproducible metric of repolarization lability on the 10-second ECG.
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QT Variability paradox after premature ventricular contraction in patients with structural heart disease and ventricular arrhythmias
Journal of electrocardiology, 2012Co-Authors: Durgesh Das, Lichy Han, Ronald D. Berger, Larisa G. TereshchenkoAbstract:Background: Increased repolarization lability is known to be associated with the risk of ventricular tachycardia (VT)/ventricularfibrillation (VF).Prematureventricularcontractions (PVCs)areexcluded from the analysis of QT Variability. However, QT dynamics after PVCs is poorly understood. Methods: We analyzed data of 33 patients with structural heart disease (mean age 60.5±12.1; 24 (73%) men; 26(79%) whites; 22 (67%)ischemic cardiomyopathy)and single-chamber ICD implanted for primary (28 patients, 85%) or secondary prevention of SCD. Arrhythmia group comprised 16 patients with VT/VF/death outcomes. Alive patients (n=17) without VT/VF served as controls. The baseline far-field (FF) ICD electrogram (EGM) was recorded at rest. RR and QT intervals of 15 sinus beats before and after PVC in 33 patients were analyzed. The prematurity index, C i MeanRR , where Ci is coupling interval, was used to select the most premature PVC. QT Variability index (QTVI) was
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predictive value of beat to beat QT Variability index across the continuum of left ventricular dysfunction competing risks of noncardiac or cardiovascular death and sudden or nonsudden cardiac death
Circulation-arrhythmia and Electrophysiology, 2012Co-Authors: Larisa G. Tereshchenko, Ronald D. Berger, Jeanphilippe Couderc, Iwona Cygankiewicz, Scott Mcnitt, Rafael Vázquez, Lichy Han, Sanjoli Sur, Antoni Bayesgenis, Antoni Bayés De LunaAbstract:Background— The goal of the present study was to determine the predictive value of beat-to-beat QT Variability in heart failure patients across the continuum of left ventricular dysfunction. Methods and Results— Beat-to-beat QT Variability index (QTVI), log-transformed heart rate variance, normalized QT variance, and coherence between heart rate Variability and QT Variability have been measured at rest during sinus rhythm in 533 participants of the Muerte Subita en Insuficiencia Cardiaca heart failure study (mean age, 63.1±11.7; men, 70.6%; left ventricular ejection fraction >35% in 254 [48%]) and in 181 healthy participants from the Intercity Digital Electrocardiogram Alliance database. During a median of 3.7 years of follow-up, 116 patients died, 52 from sudden cardiac death (SCD). In multivariate competing risk analyses, the highest QTVI quartile was associated with cardiovascular death (subhazard ratio, 1.67 [95% CI, 1.14–2.47]; P =0.009) and, in particular, with non-SCD (subhazard ratio, 2.91 [1.69–5.01]; P <0.001). Elevated QTVI separated 97.5% of healthy individuals from subjects at risk for cardiovascular (subhazard ratio, 1.57 [1.04–2.35]; P =0.031) and non-SCD in multivariate competing risk model (subhazard ratio, 2.58 [1.13–3.78]; P =0.001). No interaction between QTVI and left ventricular ejection fraction was found. QTVI predicted neither noncardiac death ( P =0.546) nor SCD ( P =0.945). Decreased heart rate Variability rather than increased QT Variability was the reason for increased QTVI in the present study. Conclusions— Increased QTVI because of depressed heart rate Variability predicts cardiovascular mortality and non-SCD but neither SCD nor extracardiac mortality in heart failure across the continuum of left ventricular dysfunction. Abnormally augmented QTVI separates 97.5% of healthy individuals from heart failure patients at risk.
Mathias Baumert - One of the best experts on this subject based on the ideXlab platform.
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QT Variability improves risk stratification in patients with dilated cardiomyopathy
Physiological measurement, 2015Co-Authors: C. Fischer, Mathias Baumert, Andrea Seeck, Rico Schroeder, Matthias Goernig, Alexander Schirdewan, H. R. Figulla, Andreas VossAbstract:Recently it could be demonstrated that systolic and diastolic blood pressure Variability (BPV) as well as segmented Poincare plot analysis (SPPA) contribute to risk stratification in patients suffering from dilated cardiomyopathy (DCM). The aim of this study was to improve the risk stratification applying a multivariate technique including QT Variability (QTV). We enrolled and significantly separated 56 low risk and 13 high risk DCM patients by nearly all applied BPV and QTV methods, but not with traditional heart rate Variability analysis. The optimum set of two indices calculating the multivariate discriminate analysis (DA) included one BPV index calculated by symbolic dynamics method (DBP(Shannon)) and one index calculated from QTV (QTV(log)) achieving an area under the receiver operating characteristics curve (AUC) of 92%, sensitivity of 92.3% and specificity of 89.3%. Performing only electrocardiogram analysis, the optimum multivariate approach including indices from segmented Poincare plot analysis and QTV still achieved a remarkable AUC of 88.3%. Increasing the number of indices for multivariate DA up to three, we achieved an AUC of 95.7%, sensitivity of 100% and specificity of 85.7% including one clinical, one BPV and one QTV index. Summarizing, we identified DCM patients with an increased risk of sudden cardiac death applying QTV analysis in a multivariate approach.
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QT Variability analysis for risk stratification in patients with dilated cardiomyopathy
2014 8th Conference of the European Study Group on Cardiovascular Oscillations (ESGCO), 2014Co-Authors: C. Fischer, Mathias Baumert, Andrea Seeck, Rico Schroeder, Matthias Goernig, Alexander Schirdewan, H. R. Figulla, Andreas VossAbstract:Recently it could be demonstrated that systolic and diastolic blood pressure Variability (BPV) as well as segmented Poincare plot analysis (SPPA) contribute to risk stratification in patients suffering from dilated cardiomyopathy (DCM). The aim of this study was to further improve the risk stratification applying multivariate technique including QT Variability (QTV). 56 low risk and 13 high risk DCM patients were enrolled and significantly separated by nearly all methods except traditional heart rate Variability analysis. The optimum set of indices included the diastolic BPV index DBP_Shannon and the index QTV_log achieving an area under the receiver operating characteristics curve (AUC) of 92%, sensitivity of 92.3% and specificity of 89.3%. Without BPV analysis the optimum multivariate approach including indices from SPPA and QTV achieved an AUC of 88.3%. Summarizing, we identified DCM patients with an increased risk of sudden cardiac death applying QTV analysis in a multivariate approach.
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Measurement of QT Variability by two-dimensional warping
2014 8th Conference of the European Study Group on Cardiovascular Oscillations (ESGCO), 2014Co-Authors: Sebastian Zaunseder, Martin Schmidt, Hagen Malberg, Mathias BaumertAbstract:This contribution presents a novel warping method, two-dimensional signal warping (2DSW), for tracking beat-to-beat changes in time intervals from electrocardiograms. To evaluate the efficiency of 2DSW to capture subtle changes in the QT interval we apply 2DSW to the Physionet QT database. It is shown that 2DSW allows highly accurate tracking of QRS-onset and T-end, which renders the method useful for future clinical applications, in particular beat-to-beat Variability analysis of ECG features.
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Decoupling of QT interval Variability from heart rate Variability with ageing
Physiological measurement, 2013Co-Authors: Mathias Baumert, Alberto Porta, Barbora Czippelova, Michal JavorkaAbstract:Ageing has been associated with changes in cardiac electrophysiology that result in QT interval prolongation. The effect of age on rate-adaptation dynamics of the QT interval is less well understood. The aim of this study was to assess age-related changes in the temporal relationship between QT and RR interval Variability. Resting ECG of 20 young and 20 elderly healthy subjects were analyzed. Beat-to-beat RR and QT interval time series were automatically extracted. Coupling between QT and RR was assessed by means of the QT Variability index, coherence in the frequency domain, rate-corrected QT interval, cross-multiscale entropy, information based similarity index and joint symbolic dynamics. In addition to QT interval prolongation (433 ± 31 versus 405 ± 33 ms, p = 0.008), elderly subjects were characterized by a significantly increased QT Variability index (-1.26 ± 0.28 versus -1.52 ± 0.22 ms, p < 0.0001), reduced coherence in high (0.11 ± 0.09 versus 0.29 ± 0.14 ms, p = 0.003), and low frequency bands (0.20 ± 0.16 versus 0.49 ± 0.15 ms, p < 0.0001), reduced information domain synchronization index (0.13 ± 0.07 versus 0.19 ± 0.05 ms, p = 0.001) as well as increased entropy and disparity in joint symbolic dynamics of QT and RR interval time series. In conclusion, ageing is associated with decoupling of QT Variability from heart rate Variability. Complexity analysis in addition to standard metrics may provide additional insight.
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Autonomic modulation of repolarization instability in patients with heart failure prone to ventricular tachycardia
American journal of physiology. Heart and circulatory physiology, 2013Co-Authors: S. Nayyar, M A Hasan, Prashanthan Sanders, Kurt C. Roberts-thomson, Thomas Sullivan, J. Harrington, Mathias BaumertAbstract:QT Variability (QTV) signifies repolarization lability, and increased QTV is a risk predictor for sudden cardiac death. The aim of the present study was to investigate the role of autonomic nervous...
