QT‐interval abnormalities in hypertrophic cardiomyopathy

Abstract

To examine whether QTc and QTc dispersion across the leads of a surface electrocardiogram (ECG) are different in patients with hypertrophic cardiomyopathy (HCM) compared with normal subjects, we measured QT and calculated QTc in all 12 leads of a surface ECG in 24 patients with HCM and in 20 age‐ and sex‐matched normal control subjects. Maximal QTc was prolonged in HCM patients (465±24 ms) compared with controls (410±20 ms) (p<0.001). QTc dispersion defined as the difference of maximum‐minimum QTc was also greater in HCM patients (71±21 ms) compared with normals (35±11 ms) (p<0.001). A correlation was found between the degree of left ventricular hypertrophy expressed by the maximal wall thickness and maximal QTc (r=0.48, p<0.02). However, QTc dispersion did not correlate with maximal wall thickness. Thus, patients with HCM show a prolonged QTc (>440 ms) and increased QTc dispersion compared with normal subjects. In addition, the degree of left ventricular hypertrophy correlates with maximal QTc. The presence of a prolonged QT with increased regional dispersion may be associated with the occurrence of serious ventricular arrhythmia and sudden death in HCM. Copyright © 1992 Wiley Periodicals, Inc.