Non-sustained ventricular tachycardia in hypertrophic cardiomyopathy: an independent marker of sudden death risk in young patients.

OBJECTIVES

The aim of this study was to examine the characteristics of non-sustained ventricular tachycardia (NSVT) episodes during Holter monitoring and to determine their relationship to age and prognosis.

BACKGROUND

It has been suggested that NSVT is only of prognostic importance in patients with hypertrophic cardiomyopathy (HCM) when repetitive, prolonged, or associated with symptoms.

METHODS

We studied 531 patients with HCM (323 male, 39 +/- 15 years). All underwent ambulatory electrocardiogram monitoring (41 +/- 11 h).

RESULTS

A total of 104 patients (19.6%) had NSVT. The proportion of patients with NSVT increased with age (p = 0.008). Maximum left ventricular wall thickness and left atrial size were greater in patients with NSVT. Mean follow-up was 70 +/- 40 months. Sixty-eight patients died, 32 from sudden cardiac death (SCD). Twenty-one patients received an implantable cardioverter defibrillator (ICD). There were four appropriate ICD discharges. In patients < or =30 years (but not >30), five-year freedom from sudden death was lower in those with NSVT (77.6% [95% confidence interval (CI): 59.8 to 95.4] vs. 94.1% [95% CI: 90.2 to 98.0]; p = 0.003). There was no relation between the duration, frequency, or rate of NSVT runs and prognosis at any age. The odds ratio of sudden death in patients < or =30 years of age with NSVT was 4.35 (95% CI: 1.54 to 12.28; p = 0.006) compared with 2.16 (95% CI: 0.82 to 5.69; p = 0.1) in patients >30 years of age.

CONCLUSIONS

Non-sustained ventricular tachycardia is associated with a substantial increase in sudden death risk in young patients with HCM. A relation between the frequency, duration, and rate of NSVT episodes could not be demonstrated.