Hypertrophic cardiomyopathy and left ventricular non compaction: Relationship between ventricular mass and shortened QRS duration

Introduction Structural heart disease may be involved in the occurrence of cardiac arrhythmias and sudden death. Increase in QRS duration is an accepted marker for arrhythmic events and SD. However, consequences of decreased QRS durations are unknown. Some genetic cardiomyopathies may be associated with very narrow QRS. Aim To determine the association between an increased myocardial mass in a population of sarcomeric hypertrophic cardiomyopathy and left ventricular non compaction population and a shortened duration of ventricular depolarization. Methods Patients with sarcomeric hypertrophic cardiomyopathy (HCM), left ventricular non compaction (LVNC), post hypertensive left ventricular hypertrophy (LVH) and controls with healthy heart were retrospectively included. Calculation of left ventricular mass (LVM) on MRI was correlated to automatic measurement of QRS duration on ECG. Potential confounding factors that can modify intraventricular conduction and ECG were collected. Results Preliminary analysis included 51 patients with HCM, 8 NCVG, 12 LVH and 39 controls. Median duration of QRS was 91 ms [IC 95% 84–99.5] in HCM, 85 ms [IC 95% 81–91] in LVNC, 97 ms [IC 95% 91–99.7] in LVH and 90 ms [IC 95% 85–96] in controls, P = 0.19. LVM was 81 g/m2 [IC 95% 63–103], 97 g/m2 [IC 95% 77–115], 76 g/m2 [IC 95% 59–126] and 53 g/m2 [IC 95% 39–59] respectively, P  Conclusion QRS duration increase with LVM in LVNC, LVH and controls while tending to decrease in HCM although non significantly. The myocardial thickness in this population may then be a reflection of a more developed Purkinje network, which is responsible for faster ventricular activation. When confirmed, these results may be used in the future for enhance diagnosis.