Ventricular Tachycardia Most Common Arrhythmia in Hypertrophic Cardiomyopathy

The most common arrhythmia in patients with hypertrophic cardiomyopathy (HCM) is ventricular tachycardia (VT), which is associated with higher left ventricular (LV) diameters and lower LV ejection fraction (LVEF) and is responsive to antitachycardia pacing, according to study findings published in Heart Rhythm.

Investigators sought to determine the predictors and incidence of sustained VTAs in patients with HCM. They conducted an observational retrospective study that included 207 patients that had a cardioverter-defibrillator (ICD) among 1328 patients with HCM. Data were from a registry at 2 tertiary medical centers (Chaim Sheba Medical Center in Tel HaShomer, Israel, and Complexo Hospitalario Universitario A Coruña, Spain). HCM was defined as unexplained LV wall thickness of 15 mm or thicker or 13 mm or thicker if the patient had a first-degree family member with HCM.

Patients with ICDs were propensity score matched to 562 patients without ICDs, though significant between-group differences remained for beta-blocker use, larger LV end-systolic diameter (LVESD), and higher proportion of patients with history of non-sustained ventricular tachycardia.

Among the 207 patients with ICDs (30% women; mean [SD] age, 33 [16] years) followed over a mean (SD) of 10 (6) years, sustained VTAs developed in 37 patients. These VTAs were associated with a personal history of VTA (with VTAs, 27% vs without, 6%; P =.001) and family history of sudden cardiac death (with VTAs, 54% vs without 34%; P =.036). Among the patients who developed VTAs, 70% had sustained monomorphic VT with or without ventricular fibrillation (VF; VT±VF group) and 30% had only VF. Compared with the VF only group, the VT±VF group had decreased LVEF and increased LV end-diastolic diameter and increased LVESD.

There were 326 VT events in 26 patients in the VT±VF group (median event rate, 2/patient; 5 patients presented with VT storm).

Overall, among the 326 VT events, 79% were successfully terminated with antitachycardia pacing (ATP). The investigators noted comparable mortality rates between patients with vs without ICDs (16% vs 20%; P =.367) and between patients with vs without VTAs (17% vs 15%; P =.270).

Across follow-up, cumulative all-cause mortality rates were similar among matched pairs (with ICD, 16%; without, 20%; P =.367).

In univariate analysis, events of VT were associated with decreasing LVEF and increasing LV dimensions (both LV end-diastolic diameter and LVESD). In multivariate analysis, LVEF and LVESD remained independently associated with VT.

Study limitations include the participants being higher risk than the general population, which reduces generalizability. The sample size is also underpowered in some analyses. Additionally, there are significant between-ICD-group characteristic differences.

“VT rather than VF is the most common arrhythmia in patients with HCM; it is amenable to ATP and is associated with lower LV ejection fraction and higher LV diameters,” the investigators wrote. “HCM patients with LVEF [of less than] 60% are more likely to present with VT, with or without VF, and therefore a transvenous ICD with ATP abilities should be considered for these patients.”