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Romagnoli S, Perez C, Burattini L, Pueyo E, Morettini M, Sbrollini A, Martinez JP, Laguna P. Model-based Estimators of QT Series Time Delay in Following Heart-Rate Changes. ANNUAL INTERNATIONAL CONFERENCE OF THE IEEE ENGINEERING IN MEDICINE AND BIOLOGY SOCIETY. IEEE ENGINEERING IN MEDICINE AND BIOLOGY SOCIETY. ANNUAL INTERNATIONAL CONFERENCE 2023; 2023:1-4. [PMID: 38083783 DOI: 10.1109/embc40787.2023.10340130] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/18/2023]
Abstract
Sudden cardiac death is the leading cause of death among cardiovascular diseases. Markers for patient risk stratification focusing on QT-interval dynamics in response to heart-rate (HR) changes can be characterized in terms of parametric QT to RR dependence and QT/RR hysteresis. The QT/RR hysteresis can be quantified by the time delay the QT interval takes to accommodate for the HR changes. The exercise stress test has been proposed as a proper test, with large HR dynamics, to evaluate the QT/RR hysteresis. The present study aims at evaluating several time-delay estimators based on noise statistic (Gaussian or Laplacian) and HR changes profile at stress test (gradual transition change). The estimator's performance was assessed on a simulated QT transition contaminated by noise and in a clinical study including patients affected by coronary arteries disease (CAD). As expected, the Laplacian and Gaussian estimators yield the best results when noise follows the respective distribution. Further, the Laplacian estimator showed greater discriminative power in classifying different levels of cardiac risk in CAD patients, suggesting that real data fit better the Laplacian distribution than the Gaussian one. The Laplacian estimator appears to be the choice for time-delay estimation of QT/RR hysteresis lag in response to HR changes in stress test.Clinical Relevance-The proposed time-delay estimator of QT/RR hysteresis lag improves its significance as biomarkers for coronary artery diseases risk stratification.
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Mercik J, Radziejewska J, Pach K, Zawadzki G, Zyśko D, Gajek J. ST-segment depression in atrioventricular nodal reentrant tachycardia: Important finding or just an artifact? Medicine (Baltimore) 2022; 101:e31806. [PMID: 36626431 PMCID: PMC9750532 DOI: 10.1097/md.0000000000031806] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 01/11/2023] Open
Abstract
BACKGROUND The ST segment is component of the QRS-T complex located between the QRS and the T wave. ST segment changes during tachycardia with narrow QRS mainly takes the form of ST segment depression. This phenomenon is often observed in young healthy people for whom an ischemic background is unlikely. MATERIALS AND METHODS The study included 104 patients (71 women and 33 men) with paroxysmal narrow QRS complex tachycardia. In all patients electrophysiological study was performed and the diagnosis of atrioventricular nodal reentrant tachycardia was established. The arrhythmogenic substrate was then eliminated successfully by subsequent ablation using radiofrequency energy which confirmed the diagnosis, all patients had measured QRS components - QR, RS and RJ during the tachycardia and during the sinusrhythm. All of the measurements were done in lead V5. RESULTS The difference RJ-QR during tachycardia and sinus rhythm correlated negatively with tachycardia cycle length (R = 0.356, P = .001), first slowly, then rapidly reaching the cycle value of about 300 ms, then it decreases, stabilizing at the cycle level of about 270. By separating the RJ-QR in tachycardia and in the sinus rhythm from the tachycardia cycle, we can see that the correlation described in this point is largely due to the correlation between the heart rate and RJ-QR length in tachycardia. CONCLUSIONS In patients with atrioventricular nodal reentrant tachycardia, there is a significant ST-segment depression during tachycardia episodes and the degree of this change is related to tachycardia cycle length. The most probable explanation of the ST-segment depression is the overlap of the QRS complex on the preceded T wave. This phenomenon is also influenced by some intrinsic properties of the individual electrocardiogram. It is possible to rule out ischemic origin of the presented ST segment change.
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Affiliation(s)
- Jakub Mercik
- Department of Emergency Medicine, Wroclaw Medical University, Poland
| | | | - Katarzyna Pach
- Students’ Scientific Association, Department of Emergency Medical Service, Wroclaw Medical University, Poland
| | - Grzegorz Zawadzki
- Students’ Scientific Association, Department of Emergency Medical Service, Wroclaw Medical University, Poland
| | - Dorota Zyśko
- Department of Emergency Medicine, Wroclaw Medical University, Poland
| | - Jacek Gajek
- Department of Emergency Medical Service, Wroclaw Medical University, Poland
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Dahlberg P, Axelsson K, Jensen SM, Lundahl G, Vahedi F, Perkins R, Gransberg L, Bergfeldt L. Accelerated QT adaptation following atropine-induced heart rate increase in LQT1 patients versus healthy controls: A sign of disturbed hysteresis. Physiol Rep 2022; 10:e15487. [PMID: 36324292 PMCID: PMC9630760 DOI: 10.14814/phy2.15487] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/04/2022] [Revised: 09/08/2022] [Accepted: 09/19/2022] [Indexed: 06/16/2023] Open
Abstract
Hysteresis, a ubiquitous regulatory phenomenon, is a salient feature of the adaptation of ventricular repolarization duration to heart rate (HR) change. We therefore compared the QT interval adaptation to rapid HR increase in patients with the long QT syndrome type 1 (LQT1) versus healthy controls because LQT1 is caused by loss-of-function mutations affecting the repolarizing potassium channel current IKs , presumably an important player in QT hysteresis. The study was performed in an outpatient hospital setting. HR was increased in LQT1 patients and controls by administering an intravenous bolus of atropine (0.04 mg/kg body weight) for 30 s. RR and QT intervals were recorded by continuous Frank vectorcardiography. Atropine induced transient expected side effects but no adverse arrhythmias. There was no difference in HR response (RR intervals) to atropine between the groups. Although atropine-induced ΔQT was 48% greater in 18 LQT1 patients than in 28 controls (p < 0.001), QT adaptation was on average 25% faster in LQT1 patients (measured as the time constant τ for the mono-exponential function and the time for 90% of ΔQT; p < 0.01); however, there was some overlap between the groups, possibly a beta-blocker effect. The shorter QT adaptation time to atropine-induced HR increase in LQT1 patients on the group level corroborates the importance of IKs in QT adaptation hysteresis in humans and shows that LQT1 patients have a disturbed ultra-rapid cardiac memory. On the individual level, the QT adaptation time possibly reflects the effect-size of the loss-of-function mutation, but its clinical implications need to be shown.
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Affiliation(s)
- Pia Dahlberg
- Department of Molecular and Clinical MedicineInstitute of Medicine, Sahlgrenska Academy, University of GothenburgGothenburgSweden
- Region Västra Götaland, Department of CardiologySahlgrenska University HospitalGothenburgSweden
| | - Karl‐Jonas Axelsson
- Department of Molecular and Clinical MedicineInstitute of Medicine, Sahlgrenska Academy, University of GothenburgGothenburgSweden
- Region Västra Götaland, Department of CardiologySahlgrenska University HospitalGothenburgSweden
| | - Steen M. Jensen
- Department of Public Health and Clinical Medicine, and Heart CentreUmeå UniversityUmeåSweden
| | - Gunilla Lundahl
- Department of Molecular and Clinical MedicineInstitute of Medicine, Sahlgrenska Academy, University of GothenburgGothenburgSweden
| | - Farzad Vahedi
- Department of Molecular and Clinical MedicineInstitute of Medicine, Sahlgrenska Academy, University of GothenburgGothenburgSweden
- Region Västra Götaland, Department of CardiologySahlgrenska University HospitalGothenburgSweden
| | - Rosie Perkins
- Department of Molecular and Clinical MedicineInstitute of Medicine, Sahlgrenska Academy, University of GothenburgGothenburgSweden
| | - Lennart Gransberg
- Department of Molecular and Clinical MedicineInstitute of Medicine, Sahlgrenska Academy, University of GothenburgGothenburgSweden
| | - Lennart Bergfeldt
- Department of Molecular and Clinical MedicineInstitute of Medicine, Sahlgrenska Academy, University of GothenburgGothenburgSweden
- Region Västra Götaland, Department of CardiologySahlgrenska University HospitalGothenburgSweden
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Martin-Yebra A, Sornmo L, Laguna P. QT interval Adaptation to Heart Rate Changes in Atrial Fibrillation as a Predictor of Sudden Cardiac Death. IEEE Trans Biomed Eng 2022; 69:3109-3118. [PMID: 35320083 DOI: 10.1109/tbme.2022.3161725] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
Abstract
OBJECTIVE The clinical significance of QT interval adaptation to heart rate changes has been poorly investigated in atrial fibrillation (AF), since QT delineation in the presence of f-waves is challenging. Therefore, the objective of the present study is to investigate new techniques for QT adaptation estimation in permanent AF. METHODS A multilead strategy based on generalized periodic component analysis is proposed for QT delineation, involving a spatial, linear transformation which emphasizes Twave periodicity and attenuates f-waves. QT adaptation is modeled by a linear, time-invariant filter, whose impulse response describes the dependence between the current QT interval and the preceding RR intervals, followed by a memoryless, possibly nonlinear, function. The QT adaptation time lag is determined from the estimated impulse response. RESULTS Using simulated ECGs in permanent AF, the transformed lead was found to offer more accurate QT delineation and time lag estimation than did the original ECG leads for a wide range of f-wave amplitudes (the time lag estimation error was found to be -0.2+/-0.6 s for SNR = 12 dB). In a population with chronic heart failure and permanent AF, the time lag estimated from the transformed lead was found to have the strongest, statistically significant association with sudden cardiac death (SCD) (hazard ratio = 3.49), whereas none of the original, orthogonal leads had any such association. CONCLUSIONS Periodic component analysis provides more accurate QT delineation and improves time lag estimation in AF. A prolonged adaptation time of the QT interval to heart rate changes is associated with a high risk for SCD. SIGNIFICANCE This study demonstrates that SCD risk markers, originally developed for sinus rhythm, can also be used in AF, provided that Twave periodicity is emphasized. The time lag is a potentially useful marker for identifying patients at high risk for SCD, guiding clinicians in adopting effective therapeutic decisions.
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Andršová I, Hnatkova K, Šišáková M, Toman O, Smetana P, Huster KM, Barthel P, Novotný T, Schmidt G, Malik M. Sex and Rate Change Differences in QT/RR Hysteresis in Healthy Subjects. Front Physiol 2022; 12:814542. [PMID: 35197861 PMCID: PMC8859307 DOI: 10.3389/fphys.2021.814542] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/13/2021] [Accepted: 12/15/2021] [Indexed: 11/13/2022] Open
Abstract
While it is now well-understood that the extent of QT interval changes due to underlying heart rate differences (i.e., the QT/RR adaptation) needs to be distinguished from the speed with which the QT interval reacts to heart rate changes (i.e., the so-called QT/RR hysteresis), gaps still exist in the physiologic understanding of QT/RR hysteresis processes. This study was designed to address the questions of whether the speed of QT adaptation to heart rate changes is driven by time or by number of cardiac cycles; whether QT interval adaptation speed is the same when heart rate accelerates and decelerates; and whether the characteristics of QT/RR hysteresis are related to age and sex. The study evaluated 897,570 measurements of QT intervals together with their 5-min histories of preceding RR intervals, all recorded in 751 healthy volunteers (336 females) aged 34.3 ± 9.5 years. Three different QT/RR adaptation models were combined with exponential decay models that distinguished time-based and interval-based QT/RR hysteresis. In each subject and for each modelling combination, a best-fit combination of modelling parameters was obtained by seeking minimal regression residuals. The results showed that the response of QT/RR hysteresis appears to be driven by absolute time rather than by the number of cardiac cycles. The speed of QT/RR hysteresis was found decreasing with increasing age whilst the duration of individually rate corrected QTc interval was found increasing with increasing age. Contrary to the longer QTc intervals, QT/RR hysteresis speed was faster in females. QT/RR hysteresis differences between heart rate acceleration and deceleration were not found to be physiologically systematic (i.e., they differed among different healthy subjects), but on average, QT/RR hysteresis speed was found slower after heart rate acceleration than after rate deceleration.
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Affiliation(s)
- Irena Andršová
- Faculty of Medicine, Department of Internal Medicine and Cardiology, University Hospital Brno, Masaryk University, Brno, Czechia
| | - Katerina Hnatkova
- National Heart and Lung Institute, Imperial College, London, United Kingdom
| | - Martina Šišáková
- Faculty of Medicine, Department of Internal Medicine and Cardiology, University Hospital Brno, Masaryk University, Brno, Czechia
| | - Ondřej Toman
- Faculty of Medicine, Department of Internal Medicine and Cardiology, University Hospital Brno, Masaryk University, Brno, Czechia
| | | | - Katharina M Huster
- Klinikum rechts der Isar, Technische Universität München, Munich, Germany
| | - Petra Barthel
- Klinikum rechts der Isar, Technische Universität München, Munich, Germany
| | - Tomáš Novotný
- Faculty of Medicine, Department of Internal Medicine and Cardiology, University Hospital Brno, Masaryk University, Brno, Czechia
| | - Georg Schmidt
- Klinikum rechts der Isar, Technische Universität München, Munich, Germany
| | - Marek Malik
- National Heart and Lung Institute, Imperial College, London, United Kingdom.,Faculty of Medicine, Department of Internal Medicine and Cardiology, Masaryk University, Brno, Czechia
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Harvey A, Curnier D, Dodin P, Abadir S, Jacquemet V, Caru M. OUP accepted manuscript. Eur J Prev Cardiol 2022; 29:1633-1677. [PMID: 35537006 DOI: 10.1093/eurjpc/zwac081] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 01/28/2022] [Revised: 04/15/2022] [Accepted: 04/18/2022] [Indexed: 11/13/2022]
Abstract
Current exercise recommendations make it difficult for long QT syndrome (LQTS) patients to adopt a physically active and/or athletic lifestyle. The purpose of this review is to summarize the current evidence, identify knowledge gaps, and discuss research perspectives in the field of exercise and LQTS. The first aim is to document the influence of exercise training, exercise stress, and postural change interventions on ventricular repolarization in LQTS patients, while the second aim is to describe electrophysiological measurements used to study the above. Studies examining the effects of exercise on congenital or acquired LQTS in human subjects of all ages were included. Systematic searches were performed on 1 October 2021, through PubMed (NLM), Ovid Medline, Ovid All EBM Reviews, Ovid Embase, and ISI Web of Science, and limited to articles written in English or French. A total of 1986 LQTS patients and 2560 controls were included in the 49 studies. Studies were mainly case-control studies (n = 41) and examined exercise stress and/or postural change interventions (n = 48). One study used a 3-month exercise training program. Results suggest that LQTS patients have subtype-specific repolarization responses to sympathetic stress. Measurement methods and quality were found to be very heterogeneous, which makes inter-study comparisons difficult. In the absence of randomized controlled trials, the current recommendations may have long-term risks for LQTS patients who are discouraged from performing physical activity, rendering its associated health benefits out of range. Future research should focus on discovering the most appropriate levels of exercise training that promote ventricular repolarization normalization in LQTS.
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Affiliation(s)
- Audrey Harvey
- Laboratory of Pathophysiology of EXercise (LPEX), School of Kinesiology and Physical Activity Sciences, Faculty of Medicine, University of Montreal, Montreal, Canada
- Sainte-Justine University Health Center, Research Center, Montreal, Canada
| | - Daniel Curnier
- Laboratory of Pathophysiology of EXercise (LPEX), School of Kinesiology and Physical Activity Sciences, Faculty of Medicine, University of Montreal, Montreal, Canada
- Sainte-Justine University Health Center, Research Center, Montreal, Canada
| | - Philippe Dodin
- Sainte-Justine University Health Center, Research Center, Montreal, Canada
| | - Sylvia Abadir
- Department of Pediatric Cardiology, Sainte-Justine University Health Center, Montreal, Canada
| | - Vincent Jacquemet
- Department of Pharmacology and Physiology, Faculty of Medicine, University of Montreal, Montreal, Canada
| | - Maxime Caru
- Sainte-Justine University Health Center, Research Center, Montreal, Canada
- Department of Pediatrics, Pennsylvania State University College of Medicine, Hershey, PA, USA
- Department of Public Health Sciences, Pennsylvania State University College of Medicine, Hershey, PA, USA
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Andršová I, Hnatkova K, Šišáková M, Toman O, Smetana P, Huster KM, Barthel P, Novotný T, Schmidt G, Malik M. Influence of heart rate correction formulas on QTc interval stability. Sci Rep 2021; 11:14269. [PMID: 34253795 PMCID: PMC8275798 DOI: 10.1038/s41598-021-93774-9] [Citation(s) in RCA: 24] [Impact Index Per Article: 8.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/12/2021] [Accepted: 06/30/2021] [Indexed: 12/12/2022] Open
Abstract
Monitoring of QTc interval is mandated in different clinical conditions. Nevertheless, intra-subject variability of QTc intervals reduces the clinical utility of QTc monitoring strategies. Since this variability is partly related to QT heart rate correction, 10 different heart rate corrections (Bazett, Fridericia, Dmitrienko, Framingham, Schlamowitz, Hodges, Ashman, Rautaharju, Sarma, and Rabkin) were applied to 452,440 ECG measurements made in 539 healthy volunteers (259 females, mean age 33.3 ± 8.4 years). For each correction formula, the short term (5-min time-points) and long-term (day-time hours) variability of rate corrected QT values (QTc) was investigated together with the comparisons of the QTc values with individually corrected QTcI values obtained by subject-specific modelling of the QT/RR relationship and hysteresis. The results showed that (a) both in terms of short-term and long-term QTc variability, Bazett correction led to QTc values that were more variable than the results of other corrections (p < 0.00001 for all), (b) the QTc variability by Fridericia and Framingham corrections were not systematically different from each other but were lower than the results of other corrections (p-value between 0.033 and < 0.00001), and (c) on average, Bazett QTc values departed from QTcI intervals more than the QTc values of other corrections. The study concludes that (a) previous suggestions that Bazett correction should no longer be used in clinical practice are fully justified, (b) replacing Bazett correction with Fridericia and/or Framingham corrections would improve clinical QTc monitoring, (c) heart rate stability is needed for valid QTc assessment, and (d) development of further QTc corrections for day-to-day use is not warranted.
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Affiliation(s)
- Irena Andršová
- Department of Internal Medicine and Cardiology, Faculty of Medicine, University Hospital Brno, Masaryk University, Jihlavská 20, 625 00, Brno, Czech Republic
| | - Katerina Hnatkova
- National Heart and Lung Institute, Imperial College, ICTEM, Hammersmith Campus, 72 Du Cane Rd, Shepherd's Bush, London, W12 0NN, England, UK
| | - Martina Šišáková
- Department of Internal Medicine and Cardiology, Faculty of Medicine, University Hospital Brno, Masaryk University, Jihlavská 20, 625 00, Brno, Czech Republic
| | - Ondřej Toman
- Department of Internal Medicine and Cardiology, Faculty of Medicine, University Hospital Brno, Masaryk University, Jihlavská 20, 625 00, Brno, Czech Republic
| | - Peter Smetana
- Wilhelminenspital der Stadt Wien, Montleartstraße 37, 1160, Vienna, Austria
| | - Katharina M Huster
- Klinikum rechts der Isar, Technische Universität München, Ismaninger Straße 22, 81675, Munich, Germany
| | - Petra Barthel
- Klinikum rechts der Isar, Technische Universität München, Ismaninger Straße 22, 81675, Munich, Germany
| | - Tomáš Novotný
- Department of Internal Medicine and Cardiology, Faculty of Medicine, University Hospital Brno, Masaryk University, Jihlavská 20, 625 00, Brno, Czech Republic
| | - Georg Schmidt
- Klinikum rechts der Isar, Technische Universität München, Ismaninger Straße 22, 81675, Munich, Germany
| | - Marek Malik
- National Heart and Lung Institute, Imperial College, ICTEM, Hammersmith Campus, 72 Du Cane Rd, Shepherd's Bush, London, W12 0NN, England, UK. .,Department of Internal Medicine and Cardiology, Faculty of Medicine, Masaryk University, Jihlavská 20, 625 00, Brno, Czech Republic.
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Abstract
The normal physiologic range of QRS complex duration spans between 80 and 125 ms with known differences between females and males which cannot be explained by the anatomical variations of heart sizes. To investigate the reasons for the sex differences as well as for the wide range of normal values, a technology is proposed based on the singular value decomposition and on the separation of different orthogonal components of the QRS complex. This allows classification of the proportions of different components representing the 3-dimensional representation of the electrocardiographic signal as well as classification of components that go beyond the 3-dimensional representation and that correspond to the degree of intricate convolutions of the depolarisation sequence. The technology was applied to 382,019 individual 10-s ECG samples recorded in 639 healthy subjects (311 females and 328 males) aged 33.8 ± 9.4 years. The analyses showed that QRS duration was mainly influenced by the proportions of the first two orthogonal components of the QRS complex. The first component demonstrated statistically significantly larger proportion of the total QRS power (expressed by the absolute area of the complex in all independent ECG leads) in females than in males (64.2 ± 11.6% vs 59.7 ± 11.9%, p < 0.00001—measured at resting heart rate of 60 beats per minute) while the second component demonstrated larger proportion of the QRS power in males compared to females (33.1 ± 11.9% vs 29.6 ± 11.4%, p < 0.001). The analysis also showed that the components attributable to localised depolarisation sequence abnormalities were significantly larger in males compared to females (2.85 ± 1.08% vs 2.42 ± 0.87%, p < 0.00001). In addition to the demonstration of the technology, the study concludes that the detailed convolution of the depolarisation waveform is individual, and that smoother and less intricate depolarisation propagation is the mechanism likely responsible for shorter QRS duration in females.
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Andršová I, Hnatkova K, Šišáková M, Toman O, Smetana P, Huster KM, Barthel P, Novotný T, Schmidt G, Malik M. Heart Rate Dependency and Inter-Lead Variability of the T Peak - T End Intervals. Front Physiol 2021; 11:595815. [PMID: 33384609 PMCID: PMC7769826 DOI: 10.3389/fphys.2020.595815] [Citation(s) in RCA: 6] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/17/2020] [Accepted: 10/14/2020] [Indexed: 11/24/2022] Open
Abstract
The electrocardiographic (ECG) assessment of the T peak–T end (Tpe) intervals has been used in many clinical studies, but several related physiological aspects have not been reported. Specifically, the sources of the Tpe differences between different ECG leads have not been systematically researched, the relationship of Tpe duration to underlying heart rate has not been firmly established, and little is known about the mutual correspondence of Tpe intervals measured in different ECG leads. This study evaluated 796,620 10-s 12-lead ECGs obtained from long-term Holters recorded in 639 healthy subjects (311 female) aged 33.8 ± 9.4 years. For each ECG, transformation to orthogonal XYZ lead was used to measure Tpe in the orthogonal vector magnitude (used as a reference for lead-to-lead comparisons) and to construct a three-dimensional T wave loop. The loop roundness was expressed by a ratio between its circumference and length. These ratios were significantly related to the standard deviation of Tpe durations in different ECG leads. At the underlying heart rate of 60 beats per minute, Tpe intervals were shorter in female than in male individuals (82.5 ± 5.6 vs 90.0 ± 6.5 ms, p < 0.0001). When studying linear slopes between Tpe intervals measured in different leads and the underlying heart rate, we found only minimal heart rate dependency, which was not systematic across the ECG leads and/or across the population. For any ECG lead, positive Tpe/RR slope was found in some subjects (e.g., 79 and 25% of subjects for V2 and V4 measurements, respectively) and a negative Tpe/RR slope in other subjects (e.g., 40 and 65% for V6 and V5, respectively). The steepest positive and negative Tpe/RR slopes were found for measurements in lead V2 and V4, respectively. In all leads, the Tpe/RR slope values were close to zero, indicating, on average, Tpe changes well below 2 ms for RR interval changes of 100 ms. On average, longest Tpe intervals were measured in lead V2, the shortest in lead III. The study concludes that the Tpe intervals measured in different leads cannot be combined. Irrespective of the measured ECG lead, the Tpe interval is not systematically heart rate dependent, and no heart rate correction should be used in clinical Tpe investigations.
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Affiliation(s)
- Irena Andršová
- Department of Internal Medicine and Cardiology, University Hospital Brno, Faculty of Medicine, Masaryk University, Brno, Czechia
| | - Katerina Hnatkova
- National Heart and Lung Institute, Imperial College London, London, United Kingdom
| | - Martina Šišáková
- Department of Internal Medicine and Cardiology, University Hospital Brno, Faculty of Medicine, Masaryk University, Brno, Czechia
| | - Ondřej Toman
- Department of Internal Medicine and Cardiology, University Hospital Brno, Faculty of Medicine, Masaryk University, Brno, Czechia
| | | | - Katharina M Huster
- Klinikum rechts der Isar, Technische Universität München, Munich, Germany
| | - Petra Barthel
- Klinikum rechts der Isar, Technische Universität München, Munich, Germany
| | - Tomáš Novotný
- Department of Internal Medicine and Cardiology, University Hospital Brno, Faculty of Medicine, Masaryk University, Brno, Czechia
| | - Georg Schmidt
- Klinikum rechts der Isar, Technische Universität München, Munich, Germany
| | - Marek Malik
- National Heart and Lung Institute, Imperial College London, London, United Kingdom
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Andršová I, Hnatkova K, Helánová K, Šišáková M, Novotný T, Kala P, Malik M. Problems with Bazett QTc correction in paediatric screening of prolonged QTc interval. BMC Pediatr 2020; 20:558. [PMID: 33317470 PMCID: PMC7734859 DOI: 10.1186/s12887-020-02460-8] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 10/01/2020] [Accepted: 12/08/2020] [Indexed: 02/06/2023] Open
Abstract
Background Bazett formula is frequently used in paediatric screening for the long QT syndrome (LQTS) and proposals exist that using standing rather than supine electrocardiograms (ECG) improves the sensitivity of LQTS diagnosis. Nevertheless, compared to adults, children have higher heart rates (especially during postural provocations) and Bazett correction is also known to lead to artificially prolonged QTc values at increased heart rates. This study assessed the incidence of erroneously increased QTc values in normal children without QT abnormalities. Methods Continuous 12-lead ECGs were recorded in 332 healthy children (166 girls) aged 10.7 ± 2.6 years while they performed postural manoeuvring consisting of episodes (in the following order) of supine, sitting, standing, supine, standing, sitting, and supine positions, each lasting 10 min. Detailed analyses of QT/RR profiles confirmed the absence of prolonged individually corrected QTc interval in each child. Heart rate and QT intervals were measured in 10-s ECG segments and in each segment, QTc intervals were obtained using Bazett, Fridericia, and Framingham formulas. In each child, the heart rates and QTc values obtained during supine, sitting and standing positions were averaged. QTc durations by the three formulas were classified to < 440 ms, 440–460 ms, 460–480 ms, and > 480 ms. Results At supine position, averaged heart rate was 77.5 ± 10.5 beat per minute (bpm) and Bazett, Fridericia and Framingham QTc intervals were 425.3 ± 15.8, 407.8 ± 13.9, and 408.2 ± 13.1 ms, respectively. At sitting and standing, averaged heart rate increased to 90.9 ± 10.1 and 100.9 ± 10.5 bpm, respectively. While Fridericia and Framingham formulas showed only minimal QTc changes, Bazett correction led to QTc increases to 435 ± 15.1 and 444.9 ± 15.9 ms at sitting and standing, respectively. At sitting, Bazett correction identified 51, 4, and 0 children as having the QTc intervals 440–460, 460–480, and > 480 ms, respectively. At sitting, these numbers increased to 118, 11, and 1, while on standing these numbers were 151, 45, and 5, respectively. Irrespective of the postural position, Fridericia and Framingham formulas identified only a small number (< 7) of children with QT interval between 440 and 460 ms and no children with longer QTc. Conclusion During screening for LQTS in children, the use of Bazett formula leads to a high number of false positive cases especially if the heart rates are increased (e.g. by postural manoeuvring). The use of Fridericia formula can be recommended to replace the Bazett correction not only for adult but also for paediatric ECGs.
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Affiliation(s)
- Irena Andršová
- Department of Internal Medicine and Cardiology, Faculty of Medicine, University Hospital Brno, Masaryk University, Brno, Czech Republic
| | - Katerina Hnatkova
- National Heart and Lung Institute, Imperial College, ICTEM, Hammersmith Campus, 72 Du Cane Road, Shepherd's Bush, London, W12 0NN, England
| | - Kateřina Helánová
- Department of Internal Medicine and Cardiology, Faculty of Medicine, University Hospital Brno, Masaryk University, Brno, Czech Republic
| | - Martina Šišáková
- Department of Internal Medicine and Cardiology, Faculty of Medicine, University Hospital Brno, Masaryk University, Brno, Czech Republic
| | - Tomáš Novotný
- Department of Internal Medicine and Cardiology, Faculty of Medicine, University Hospital Brno, Masaryk University, Brno, Czech Republic
| | - Petr Kala
- Department of Internal Medicine and Cardiology, Faculty of Medicine, University Hospital Brno, Masaryk University, Brno, Czech Republic
| | - Marek Malik
- National Heart and Lung Institute, Imperial College, ICTEM, Hammersmith Campus, 72 Du Cane Road, Shepherd's Bush, London, W12 0NN, England.
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11
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Toman O, Hnatkova K, Smetana P, Huster KM, Šišáková M, Barthel P, Novotný T, Schmidt G, Malik M. Physiologic heart rate dependency of the PQ interval and its sex differences. Sci Rep 2020; 10:2551. [PMID: 32054960 PMCID: PMC7018842 DOI: 10.1038/s41598-020-59480-8] [Citation(s) in RCA: 17] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/15/2019] [Accepted: 01/29/2020] [Indexed: 12/29/2022] Open
Abstract
On standard electrocardiogram (ECG) PQ interval is known to be moderately heart rate dependent, but no physiologic details of this dependency have been established. At the same time, PQ dynamics is a clear candidate for non-invasive assessment of atrial abnormalities including the risk of atrial fibrillation. We studied PQ heart rate dependency in 599 healthy subjects (aged 33.5 ± 9.3 years, 288 females) in whom drug-free day-time 12-lead ECG Holters were available. Of these, 752,517 ECG samples were selected (1256 ± 244 per subject) to measure PQ and QT intervals and P wave durations. For each measured ECG sample, 5-minute history of preceding cardiac cycles was also obtained. Although less rate dependent than the QT intervals (36 ± 19% of linear slopes), PQ intervals were found to be dependent on underlying cycle length in a highly curvilinear fashion with the dependency significantly more curved in females compared to males. The PQ interval also responded to the heart rate changes with a delay which was highly sex dependent (95% adaptation in females and males after 114.9 ± 81.1 vs 65.4 ± 64.3 seconds, respectively, p < 0.00001). P wave duration was even less rate dependent than the PQ interval (9 ± 10% of linear QT/RR slopes). Rate corrected P wave duration was marginally but significantly shorter in females than in males (106.8 ± 8.4 vs 110.2 ± 7.9 ms, p < 0.00001). In addition to establishing physiologic standards, the study suggests that the curvatures and adaptation delay of the PQ/cycle-length dependency should be included in future non-invasive studies of atrial depolarizations.
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Affiliation(s)
- Ondřej Toman
- Department of Internal Medicine and Cardiology, University Hospital Brno, Faculty of Medicine, Masaryk University, Jihlavská 20, 625 00, Brno, Czech Republic
| | - Katerina Hnatkova
- National Heart and Lung Institute, Imperial College, 72 Du Cane Rd, Shepherd's Bush, London, W12 0NN, England
| | - Peter Smetana
- Wilhelminenspital der Stadt Wien, Montleartstraße 37, 1160, Vienna, Austria
| | - Katharina M Huster
- Klinikum rechts der Isar, Technische Universität München, Ismaninger Straße 22, D-81675, Munich, Germany
| | - Martina Šišáková
- Department of Internal Medicine and Cardiology, University Hospital Brno, Faculty of Medicine, Masaryk University, Jihlavská 20, 625 00, Brno, Czech Republic
| | - Petra Barthel
- Klinikum rechts der Isar, Technische Universität München, Ismaninger Straße 22, D-81675, Munich, Germany
| | - Tomáš Novotný
- Department of Internal Medicine and Cardiology, University Hospital Brno, Faculty of Medicine, Masaryk University, Jihlavská 20, 625 00, Brno, Czech Republic
| | - Georg Schmidt
- Klinikum rechts der Isar, Technische Universität München, Ismaninger Straße 22, D-81675, Munich, Germany
| | - Marek Malik
- National Heart and Lung Institute, Imperial College, 72 Du Cane Rd, Shepherd's Bush, London, W12 0NN, England.
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Implications of Individual QT/RR Profiles-Part 1: Inaccuracies and Problems of Population-Specific QT/Heart Rate Corrections. Drug Saf 2020; 42:401-414. [PMID: 30255349 PMCID: PMC6426828 DOI: 10.1007/s40264-018-0736-1] [Citation(s) in RCA: 10] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/12/2022]
Abstract
Introduction Universal QT correction formulas are potentially problematic in corrected QT (QTc) interval comparisons at different heart rates. Instead of individual-specific corrections, population-specific corrections are occasionally used based on QT/RR data pooled from all study subjects. Objective To investigate the performance of individual-specific and population-specific corrections, a statistical modeling study was performed using QT/RR data of 523 healthy subjects. Methods In each subject, full drug-free QT/RR profiles were available, characterized using non-linear regression models. In each subject, 50 baseline QT/RR readings represented baseline data of standard QT studies. Using these data, linear and log-linear heart rate corrections were optimized for each subject and for different groups of ten and 50 subjects. These corrections were applied in random combinations of heart rate changes between − 10 and + 25 beats per minute (bpm) and known QTc interval changes between − 25 and + 25 ms. Results Both the subject-specific and population-specific corrections based on the 50 baseline QT/RR readings tended to underestimate/overestimate the QTc interval changes when heart rate was increasing/decreasing, respectively. The result spread was much wider with population-specific corrections, making the estimates of QTc interval changes practically unpredictable. Conclusion Subject-specific heart rate corrections based on limited baseline drug-free data may lead to inconsistent results and, in the presence of underlying heart rate changes, may potentially underestimate or overestimate QTc interval changes. The population-specific corrections lead to results that are much more influenced by the combination of individual QT/RR patterns than by the actual QTc interval changes. Subject-specific heart rate corrections based on full profiles derived from drug-free baseline recordings with wide QT/RR distribution should be used when studying drugs expected to cause heart rate changes. Electronic supplementary material The online version of this article (10.1007/s40264-018-0736-1) contains supplementary material, which is available to authorized users.
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Implications of Individual QT/RR Profiles-Part 2: Zero QTc/RR Correlations Do Not Prove QTc Correction Accuracy in Studies of QTc Changes. Drug Saf 2020; 42:415-426. [PMID: 30255348 PMCID: PMC6426831 DOI: 10.1007/s40264-018-0735-2] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/12/2022]
Abstract
Introduction In studies of drug-induced corrected QT (QTc) changes, fixed universal heart rate (HR) corrections (e.g., the Fridericia correction) are potentially misleading when assessing the effects of drugs that change HR. When data-specific corrections are designed, tests of their validity are needed. The proposed tests include zero correlations between QTc and corresponding RR values in the complete study data (pooling on-treatment and off-treatment interval measurements). Objective To document that this approach is potentially highly misleading, a statistical modeling study was conducted based on the full profiles of QT/RR data of 523 healthy subjects—254 females, mean age 33.5 years. Methods In each of the subjects, 50 baseline QT/RR readings were selected to model baseline data. In repeated experiments, groups of ten and 50 subjects were randomly selected and drug-induced HR increases between 0 and 25 beats per minute combined with QTc changes between − 20 and + 20 ms were modeled. In each experiment, subject-specific as well as population-specific HR corrections were designed so that the QTc interval data were uncorrelated to the corresponding RR interval data. Results The simulation experiments showed that when zero correlations of QTc data with RR data are combined with more than trivial HR increases, the HR corrections are substantially biased and underestimate or fully eliminate any drug-induced QTc interval changes. This result is in full agreement with theoretical considerations of HR correction principles. Conclusions The lack of correlation of QTc versus RR durations including on-treatment data does not prove any validity of HR corrections. Correlations of QTc versus RR in study data pooling on- and off-drug measurements should not be used to prove the appropriateness of HR corrections. Electronic supplementary material The online version of this article (10.1007/s40264-018-0735-2) contains supplementary material, which is available to authorized users.
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Hnatkova K, Toman O, Šišáková M, Smetana P, Huster KM, Barthel P, Novotný T, Schmidt G, Malik M. Sex and race differences in J-Tend, J-Tpeak, and Tpeak-Tend intervals. Sci Rep 2019; 9:19880. [PMID: 31882660 PMCID: PMC6934529 DOI: 10.1038/s41598-019-56328-8] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/17/2019] [Accepted: 12/10/2019] [Indexed: 11/19/2022] Open
Abstract
To facilitate the precision of clinical electrocardiographic studies of J-to-Tpeak (JTp) and Tpeak-to-Tend (Tpe) intervals, the study investigated their differences between healthy females and males, and between subjects of African and Caucasian origin. In 523 healthy subjects (254 females; 236 subjects of African origin), repeated Holter recordings were used to measure QT, JT, JTp, and Tpe intervals preceded by both stable and variable heart rates. Subject-specific curvilinear regression models were used to obtain individual QTc, JTc, JTpc and Tpec intervals. Rate hysteresis, i.e., the speed with which the intervals adapted after heart rate changes, was also investigated. In all sex-race groups, Tpe intervals were not systematically heart rate dependent. Similar to QTc intervals, women had JTc, and JTpc intervals longer than males (difference 20–30 ms, p < 0.001). However, women had Tpec intervals (and rate uncorrected Tpe intervals) shorter by approximately 10 ms compared to males (p < 0.001). Subjects of African origin had significantly shorter QTc intervals than Caucasians (p < 0.001). Gradually diminishing race-difference was found for JTc, JTpc and Tpec intervals. JTc and JTpc were moderately increasing with age but Tpe/Tpec were not. Rate hysteresis of JTp was approximately 10% longer compared to that of JT (p < 0.001). In future clinical studies, Tpe interval should not be systematically corrected for heart rate and similar to the QT interval, the differences in JT, JTp and Tpe intervals should be corrected for sex. The differences in QT and JT, and JTp intervals should also be corrected for race.
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Affiliation(s)
- Katerina Hnatkova
- National Heart and Lung Institute, Imperial College, 72 Du Cane Road, Shepherd's Bush, London, W12 0NN, England
| | - Ondřej Toman
- Department of Internal Medicine and Cardiology, University Hospital Brno, Faculty of Medicine, Masaryk University, Jihlavská 20, 625 00, Brno, Czech Republic
| | - Martina Šišáková
- Department of Internal Medicine and Cardiology, University Hospital Brno, Faculty of Medicine, Masaryk University, Jihlavská 20, 625 00, Brno, Czech Republic
| | - Peter Smetana
- Wilhelminenspital der Stadt Wien, Montleartstraße 37, 1160, Vienna, Austria
| | - Katharina M Huster
- Klinikum rechts der Isar, Technische Universität München, Ismaninger Straße 22, D-81675, Munich, Germany
| | - Petra Barthel
- Klinikum rechts der Isar, Technische Universität München, Ismaninger Straße 22, D-81675, Munich, Germany
| | - Tomáš Novotný
- Department of Internal Medicine and Cardiology, University Hospital Brno, Faculty of Medicine, Masaryk University, Jihlavská 20, 625 00, Brno, Czech Republic
| | - Georg Schmidt
- Klinikum rechts der Isar, Technische Universität München, Ismaninger Straße 22, D-81675, Munich, Germany
| | - Marek Malik
- National Heart and Lung Institute, Imperial College, 72 Du Cane Road, Shepherd's Bush, London, W12 0NN, England.
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Hnatkova K, Malik M. Sources of QTc variability: Implications for effective ECG monitoring in clinical practice. Ann Noninvasive Electrocardiol 2019; 25:e12730. [PMID: 31760674 PMCID: PMC7358850 DOI: 10.1111/anec.12730] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 10/18/2019] [Accepted: 10/23/2019] [Indexed: 01/02/2023] Open
Abstract
Pharmaceuticals that prolong ventricular repolarization may be proarrhythmic in susceptible patients. While this fact is well recognized, schemes for sequential QTc interval monitoring in patients receiving QT‐prolonging drugs are frequently overlooked or, if implemented, underutilized in clinical practice. There are several reasons for this gap in day‐to‐day clinical practice. One of these is the perception that serially measured QTc intervals are subject to substantial variability that hampers the distinction between potential proarrhythmic signs and other sources of QTc variability. This review shows that substantial part of the QTc variability can be avoided if more accurate methodology for electrocardiogram collection, measurement, and interpretation is used. Four aspects of such a methodology are discussed. First, advanced methods for QT interval measurement are proposed including suggestion of multilead measurements in problematic recordings such as those in atrial fibrillation patients. Second, serial comparisons of T‐wave morphologies are advocated instead of simple acceptance of historical QTc measurements. Third, the necessity of understanding the pitfalls of heart rate correction is stressed including the necessity of avoiding the Bazett correction in cases of using QTc values for clinical decisions. Finally, the frequently overlooked problem of QT‐heart rate hysteresis is discussed including the possibility of gross QTc errors when correcting the QT interval for simultaneously measured short‐term heart rate.
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Affiliation(s)
| | - Marek Malik
- National Heart and Lung Institute, Imperial College, London, UK
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16
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Abstract
Drug-induced changes of the J to T peak (JTp) and J to the median of area under the T wave (JT50) were reported to differentiate QT prolonging drugs that are predominant blockers of the delayed potassium rectifier current from those with multiple ion channel effects. Studies of drug-induced JTp/JT50 interval changes might therefore facilitate cardiac safety evaluation of new pharmaceuticals. It is not known whether formulas for QT heart rate correction are applicable to JTp and JT50 intervals. QT/RR, JTp/RR, and JT50/RR profiles were studied in 523 healthy subjects aged 33.5 ± 8.4 years (254 females). In individual subjects, 1,256 ± 220 electrocardiographic measurements of QT, JTp, and JT50 intervals were available including a 5-minute history of RR intervals preceding each measurement. Curvilinear, linear and log-linear regression models were used to characterize individual QT/RR, JTp/RR, and JT50/RR profiles both without and with correction for heart rate hysteresis. JTp/RR and JT50/RR hysteresis correction needs to be included but the generic universal correction for QT/RR hysteresis is also applicable to JTp/RR and JT50/RR profiles. Once this is incorporated, median regression coefficients of the investigated population suggest linear correction formulas JTpc = JTp + 0.150(1-RR) and JT50c = JT50 + 0.117(1-RR) where RR intervals of the underlying heart rate are hysteresis-corrected, and all measurements expressed in seconds. The established correction formulas can be proposed for future clinical pharmacology studies that show drug-induced heart rate changes of up to approximately 10 beats per minute.
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17
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Andršová I, Hnatkova K, Helánová K, Šišáková M, Novotný T, Kala P, Malik M. Individually Rate Corrected QTc Intervals in Children and Adolescents. Front Physiol 2019; 10:994. [PMID: 31427990 PMCID: PMC6688657 DOI: 10.3389/fphys.2019.00994] [Citation(s) in RCA: 12] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/27/2019] [Accepted: 07/18/2019] [Indexed: 11/13/2022] Open
Abstract
Accurate evaluation of the appearance of QTc sex differences during childhood and adolescence is intricate. Inter-subject differences of individual QT/RR patterns make generic heart rate corrections inaccurate because of fast resting heart rates in children. The study investigated 527 healthy children and adolescents aged 4–19 years (268 females, 50.9%). All underwent continuous ECG 12-lead monitoring while performing postural changes during a 70-min investigative protocol to obtain QT interval measurements at different heart rates. On average, more than 1200 ECG measurements (QT interval and its 5-min history of preceding RR intervals) were made in each subject. Curvilinear QT/RR regression involving intra-individual correction for QT/RR hysteresis were calculated in each subject. The projection of the QT/RR regressions to the heart rate of 60 beats per minute defined individually corrected QTc intervals. In males, gradual QTc shortening by about 15 ms appeared during the ages of 13–19 years synchronously with the incidence of secondary sex signs (p = 0.016). On the contrary, whilst gradual QTc prolongation by about 10 ms appeared in females, it occurred only during ages 16–19 years and was not related to the incidence of secondary sex signs (p = 0.18). The study also showed that in children and adolescents, linear QT/RR models fit the intra-subject data significantly more closely than the log-linear models (p < 0.001). The study speculates that hormonal shifts during puberty might be directly responsible for the QTc shortening in males but that QTc prolongation in females is likely more complex since it was noted to follow the appearance of secondary sex signs only after a considerable delay.
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Affiliation(s)
- Irena Andršová
- Department of Internal Medicine and Cardiology, University Hospital Brno, Faculty of Medicine, Masaryk University, Brno, Czechia
| | - Katerina Hnatkova
- National Heart and Lung Institute, Imperial College London, London, United Kingdom
| | - Kateřina Helánová
- Department of Internal Medicine and Cardiology, University Hospital Brno, Faculty of Medicine, Masaryk University, Brno, Czechia
| | - Martina Šišáková
- Department of Internal Medicine and Cardiology, University Hospital Brno, Faculty of Medicine, Masaryk University, Brno, Czechia
| | - Tomáš Novotný
- Department of Internal Medicine and Cardiology, University Hospital Brno, Faculty of Medicine, Masaryk University, Brno, Czechia
| | - Petr Kala
- Department of Internal Medicine and Cardiology, University Hospital Brno, Faculty of Medicine, Masaryk University, Brno, Czechia
| | - Marek Malik
- National Heart and Lung Institute, Imperial College London, London, United Kingdom
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18
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Hnatkova K, Vicente J, Johannesen L, Garnett C, Stockbridge N, Malik M. Errors of Fixed QT Heart Rate Corrections Used in the Assessment of Drug-Induced QTc Changes. Front Physiol 2019; 10:635. [PMID: 31275152 PMCID: PMC6591442 DOI: 10.3389/fphys.2019.00635] [Citation(s) in RCA: 14] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/23/2019] [Accepted: 05/06/2019] [Indexed: 02/06/2023] Open
Abstract
The accuracy of studies of drug-induced QTc changes depends, among others, on the accuracy of heart rate correction of QT interval. It has been recognized that when a drug leads to substantial heart rate changes, fixed universal corrections cannot be used and that alternative methods such as subject-specific corrections established for each study participant need to be considered. Nevertheless, the maximum heart rate change that permits use of fixed correction with reasonable accuracy has not been systematically investigated. We have therefore used full QT/heart-rate profiles of 751 healthy subjects (mean age 34.2 ± 9.6, range 18–61 years, 335 females) and compared their subject-specific corrections with 6 fixed corrections, namely Bazett, Fridericia, Framingham, Hodges, Rautaharju, and Sarma formulae. The comparison was based on statistical modeling experiments which simulated clinical studies of N = 10 or N = 50 female or male subjects. The experiments compared errors of ΔQTc intervals calculated as differences between QTc intervals at an initial heart rate (in the range of 40 to 120 beats per minute, bpm) and after a heart rate change (in the range from −20 to +20 bpm). The experiments also investigated errors due to spontaneous heart rate fluctuation and due to omission of correction for QT/RR hysteresis. In each experiment, the absolute value of the single-sided 90th percentile most remote from zero was used as the error estimate. Each experiment was repeated 10,000 times with random selection of modeled study group. From these repetitions, median and upper 80th percentile was derived and graphically displayed for all different combinations of initial heart rate and heart rate change. The results showed that Fridericia formula might be reasonable (with estimated errors of ΔQTc below 8 ms) in large studies if the heart rate does not change more than ± 10 bpm and that the errors by fixed corrections and the errors due to omission of QR/RR hysteresis are additive. Additionally, the results suggest that the variability introduced into QTc data by not correcting for the underlying heart rate accurately might have a greater impact in smaller studies. The errors by Framingham formula were practically the same as with the Fridericia formula. Other investigated fixed heart rate corrections led to larger ΔQTc errors.
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Affiliation(s)
- Katerina Hnatkova
- National Heart and Lung Institute, Imperial College London, London, United Kingdom
| | - Jose Vicente
- Division of Cardiovascular and Renal Products, Office of New Drugs, Center for Drug Evaluation and Research, U.S. Food and Drug Administration, Silver Spring, MD, United States
| | - Lars Johannesen
- Division of Cardiovascular and Renal Products, Office of New Drugs, Center for Drug Evaluation and Research, U.S. Food and Drug Administration, Silver Spring, MD, United States
| | - Christine Garnett
- Division of Cardiovascular and Renal Products, Office of New Drugs, Center for Drug Evaluation and Research, U.S. Food and Drug Administration, Silver Spring, MD, United States
| | - Norman Stockbridge
- Division of Cardiovascular and Renal Products, Office of New Drugs, Center for Drug Evaluation and Research, U.S. Food and Drug Administration, Silver Spring, MD, United States
| | - Marek Malik
- National Heart and Lung Institute, Imperial College London, London, United Kingdom
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19
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Malik M. Methods of Subject-Specific Heart Rate Corrections. J Clin Pharmacol 2018; 58:1020-1024. [PMID: 29873807 DOI: 10.1002/jcph.1269] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/14/2018] [Accepted: 05/15/2018] [Indexed: 12/20/2022]
Affiliation(s)
- Marek Malik
- National Heart and Lung Institute, Imperial College, London, UK
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20
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Nouraei H, Bennett M, Rabkin S. Value of the New Spline QTc Formula in Adjusting for Pacing-Induced Changes in Heart Rate. Cardiol Res Pract 2018; 2018:2052601. [PMID: 29805797 PMCID: PMC5902062 DOI: 10.1155/2018/2052601] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 10/21/2017] [Revised: 12/15/2017] [Accepted: 01/14/2018] [Indexed: 01/08/2023] Open
Abstract
AIMS To determine whether a new QTc calculation based on a Spline fit model derived and validated from a large population remained stable in the same individual across a range of heart rates (HRs). Second, to determine whether this formula incorporating QRS duration can be of value in QT measurement, compared to direct measurement of the JT interval, during ventricular pacing. METHODS Individuals (N=30; 14 males) aged 51.9 ± 14.3 years were paced with decremental atrial followed by decremental ventricular pacing. RESULTS The new QTc changed minimally with shorter RR intervals, poorly fit even a linear relationship, and did not fit a second-order polynomial. In contrast, the Bazett formula (QTcBZT) showed a steep and marked increase in QTc with shorter RR intervals. For atrial pacing data, QTcBZT was fit best by a second-order polynomial and demonstrated a dramatic increase in QTc with progressively shorter RR intervals. For ventricular pacing, the new QTc minus QRS duration did not meaningfully change with HR in contrast to the HR dependency of QTcBZT and JT interval. CONCLUSION The new QT correction formula is minimally impacted by HR acceleration induced by atrial or ventricular pacing. The Spline QTc minus QRS duration is an excellent method to estimate QTc in ventricular paced complexes.
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Affiliation(s)
- Hirmand Nouraei
- Department of Medicine (Cardiology), University of British Columbia, Vancouver, BC, Canada
| | - Matthew Bennett
- Department of Medicine (Cardiology), University of British Columbia, Vancouver, BC, Canada
| | - Simon Rabkin
- Department of Medicine (Cardiology), University of British Columbia, Vancouver, BC, Canada
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Gravel H, Jacquemet V, Dahdah N, Curnier D. Clinical applications of QT/RR hysteresis assessment: A systematic review. Ann Noninvasive Electrocardiol 2017; 23. [PMID: 29083088 DOI: 10.1111/anec.12514] [Citation(s) in RCA: 21] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 04/25/2017] [Accepted: 09/17/2017] [Indexed: 12/15/2022] Open
Abstract
BACKGROUND QT/RR hysteresis (QT-hys) is an index of the time accommodation of ventricular repolarization to heart rate changes. This report comprehensively reviews studies addressing QT-hys as a biomarker of medical conditions. METHODS This is a secondary analysis of data from a recent systematic review pertaining to methods of assessment of QT-hys. Articles included in the former review were filtered in order to select original articles investigating the association of QT-hys with medical conditions in humans. RESULTS Nineteen articles fulfilled our inclusion criteria. Given the heterogeneity of the methods and investigated conditions, no pooled analysis of data could be implemented. QT-hys was mostly studied as a risk marker of severe arrhythmias, as a predictor of the long QT syndrome (LQTS) phenotypes and genotypes and as a marker of exercise-induced ischemia. An increased QT-hys appears to be implicated in arrhythmogenesis, although the evidence in this regard relies on few human studies. An augmented QT-hys was reported in the LQTS, predominantly in the LQT2 genotype, but conflicting results were obtained between studies using different methods of assessment. In addition, QT-hys appears to be a useful marker of stress-induced myocardial ischemia in patients suspected of coronary artery disease. CONCLUSIONS QT-hys evaluation has potential clinical utility in at least some clinical conditions. Further studies of the clinical validity of QT-hys assessment are warranted, particularly condition specific studies based on QT-hys evaluation methods that provide separate estimates of QT-hys and QT/RR dependency.
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Affiliation(s)
- Hugo Gravel
- Department of Kinesiology, University of Montreal, Montreal, QC, Canada
| | - Vincent Jacquemet
- Department of Pharmacology and Physiology, Faculty of Medicine, University of Montreal, Montreal, QC, Canada
| | - Nagib Dahdah
- Division of Pediatric Cardiology and CHU Ste-Justine Research Center, CHU Ste-Justine, Montreal, QC, Canada
| | - Daniel Curnier
- Department of Kinesiology, University of Montreal, Montreal, QC, Canada
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