Determinant of QT Dispersion in Patients with Hypertrophic Cardiomyopathy

Abstract

QT dispersion is thought to reflect a regional difference in repolarization process although QT interval is composed of depolarization and repolarization. This study was designed to investigate the effect of depolarization and repolarization on QT dispersion in hypertrophic cardiomyopathy. Standard 12-lead ECG was recorded in 70 hypertrophic cardiomyopathy patients with anteroseptal wall hypertrophy (HC-As), 8 patients with lateral wall hypertrophy (HC-L), 8 patients with diffuse hypertrophy (HC-D), and 46 normal controls. QRS, JTc, maximum and minimum QTc, and QTc dispersion were compared. The maximum QTc was greater in HC-As and HC-L than in the control; the minimum QTc was similar in all 3 groups; consequently, QTc dispersion was greater in HC-As and HC-L. In HC-D, the maximum QTc and the minimum QTc were greater than the control, which produced QTc dispersion similar to that in the control. JTc did not differ among 4 groups. In hypertrophic cardiomyopathy, both QTc and QRS duration were increased in the leads coinciding with the left ventricular portion of localized hypertrophy. We conclude that QTc dispersion depended on the heterogeneity of QRS duration or depolarization rather than repolarization, which in fact may be ascribed to the regionally different hypertrophy of the left ventricle in hypertrophic cardiomyopathy.

Spatial QT Dispersion Predicts Nonsustained Ventricular Tachycardia and Correlates with Confined Systodiastolic Dysfunction in Hypertrophic Cardiomyopathy

“…β-blockers, amiodarone, calcium channel blockers, etc. ), as well as with a similar morphological pattern of LV wall hypertrophy [39,40,41]. In such a homogenous study sample, our data suggest the whole QT e dispersion as the best 12-lead surface ECG marker of NSVT risk compared with all the other QT subsegment dispersion values (QRS, QT p , T p T e , JT p , and JT e ).…”

QT spatial dispersion and sudden cardiac death in hypertrophic cardiomyopathy: Time for reappraisal

“…The mechanism underlying the above-mentioned pathophysiological link might be only hypothesized. It is reasonable that, besides the hypertrophy magnitude per se, specific gene mutation, myocardial disarray, fibrosis, and mechanical dyssynchrony might impact on the myocardial repolarization lability and, hence, the whole QT spatial dispersion [22][23][24][25][26]. Supporting this hypothesis, we previously described a poor association between the MWT and QTcd, the latter strongly associated with an echocardiographic index of global systodiastolic ventricular performance, the myocardial performance index [13].…”

QT interval instability and QRS interval dispersion in healthy cats and cats with a hypertrophic cardiomyopathy phenotype

“…Interestingly, one study that enrolled people with HCM found an increased QRSv in the affected group only when 12-lead recordings were made. 26 In our study, we assessed only the limb leads, which may have compromised the results since the QRS interval duration is subject to alteration, being longer in the precordial leads. 27,28 The values for QTa and QTac were higher in cats with HCM, which has been previously reported in cats with left ventricular hypertrophy, 7 and also in humans with HCM, 29 who share relevant similarities in the manifestations of this disease.…”

“…Interestingly, one study that enrolled people with HCM found an increased QRSv in the affected group only when 12-lead recordings were made. 26 In our study, we assessed only the limb leads, which may have compromised the results since the QRS interval duration is subject to alteration, being longer in the precordial leads. 27 , 28 …”