Prognosis of asymptomatic patients with hypertrophic cardiomyopathy and nonsustained ventricular tachycardia.

Abstract

BACKGROUND In the early 1980s, studies performed in highly selected referral patients with hypertrophic cardiomyopathy reported a strong association between the presence of brief episodes of ventricular tachycardia (VT) on ambulatory ECG monitoring and sudden death. These observations led to antiarrhythmic treatment in many patients with hypertrophic cardiomyopathy and brief episodes of VT. In recent years, however, a growing awareness of the potential arrhythmogenic effects of antiarrhythmic medications has raised doubts regarding such a therapeutic approach, particularly in less selected and lower-risk patient populations. METHODS AND RESULTS In the present study, we examined the prognostic significance of nonsustained VT in a population of 151 patients with hypertrophic cardiomyopathy who were asymptomatic or had only mild symptoms at the time of their initial ambulatory ECG recording. Of the 151 study patients, 42 had episodes of VT and 109 did not. The runs of VT ranged from 3 to 19 beats, with 35 patients (83%) having < 10 beats. The number of runs of VT ranged from 1 to 12 in 24 hours, with 36 patients (86%) having < or = 5 episodes of VT. Thus, in most patients, the episodes of VT were brief and infrequent. Follow-up averaged 4.8 years. Of the 151 study patients, 6 died suddenly, 3 in the group with VT and 3 in the group without VT. Two other patients, both in the group without VT, died of congestive heart failure. The total cardiac mortality rate was 1.4% per year in the patients with VT (95% CI, 0.4% to 3.5%) and 0.9% in those without VT (95% CI, 0.4% to 2.0%; P = .43). The relative risk of cardiac death for patients with VT was 1.4 compared with patients without VT (95% CI, 0.6 to 6.1). The sudden death rate was 1.4% per year in the patients with VT (95% CI, 0.4% to 3.5%) and 0.6% in those without VT (95% CI, 0.2% to 1.5%; P = .24). The relative risk of sudden death for patients with VT compared with those without VT was 2.4 (95% CI, 0.5 to 11.9). Of the 151 patients included in the study, 88 (58%) remained asymptomatic and were not treated with cardioactive medications during follow-up. Of these 88 patients, 20 were in the group with VT and 68 in the group without VT. None of these patients died. CONCLUSIONS Our results show that cardiac mortality is low in patients with hypertrophic cardiomyopathy who are asymptomatic or only mildly symptomatic and have brief and infrequent episodes of VT on ambulatory ECG monitoring. Our findings also suggest that brief and infrequent episodes of VT should not be considered, per se, an indication for antiarrhythmic treatment in such patients.

Significance of Maximal and Regional Left Ventricular Wall Thickness in Association With Arrhythmic Events in Patients With Hypertrophic Cardiomyopathy

“…15 To complicate matters further, various types of VAEs are associated with marked heterogeneity in the risk for SCD; whether NSVT, the predominant type of VAE in our study, represents a marker of malignant arrhythmic has also been hotly debated in many studies, which are best characterized by their heterogeneous design, populations with variety of presentations 16-19 or their highly selected patients. 20 To weigh the arrhythmic burden, others have attempted to capture the markers of risk for VAEs in terms of age, 21 histopathological/electrophysiological substrate 22-27 or imaging yield, 1-3,28-31 with the summative yield that VAEs have a low positive and a relatively high negative predictive value for SCD in HCM populations. 32 Despite the overall low likelihood of a fatal event when VAEs are present, it is the detrimental, unexpected and sudden nature that warrants the ongoing search for superior and preferably noninvasive ways of identification of those at high risk of SCD.…”

Electrophysiological abnormalities and arrhythmias in alpha MHC mutant familial hypertrophic cardiomyopathy mice.

“…In FHC patients who have survived cardiac arrest, electrophysiologic testing has demonstrated that sinus node dysfunction, electrogram fractionation, and inducible ventricular arrhythmias are common (16,25,26). Specific mutations causing FHC are associated in some patients with echocardiographic evidence for ventricular hypertrophy and morphological abnormalities (27), risk for sudden death and/or ventricular arrhythmias (28), and electrophysiological abnormalities (29,30). Current diagnostic techniques, however, such as echocardiography and cardiac catheterization, are neither sensitive nor specific predictors of sudden death in patients with familial hypertrophic cardiomyopathy.…”

ACC/AHA/ESC 2006 Guidelines for Management of Patients With Ventricular Arrhythmias and the Prevention of Sudden Cardiac Death

“…SCD is less frequently due to bradycardia (659). The annual mortality from HCM has been estimated as high as 6% from tertiary centers (653,660,661), but community-based studies suggest a more benign disease in the majority of individuals, with an annual mortality in the range of 1% or less (662)(663)(664)(665)(666)(667). This relatively low incidence creates a challenge for risk stratification because the falsepositive values for any stratifier may overwhelm the truepositive values (668).…”