Sudden death in hypertrophic cardiomyopathy: Identification of high risk patients

OBJECTIVES We sought to identify patients with hypertrophic cardiomyopathy (HCM) at high risk of sudden death (SD). BACKGROUND Relatively low mortality rates in HCM make conventional analysis of multiple clinical risk markers for SD problematic. This study used a re ferral center registry to investigate a smaller number of generally accepte d noninvasive risk markers. METHODS We studied 368 patients (14 to 65 years old, 239 males) with HCM. T here were five: variables: nonsustained ventricular tachycardia (NSVT), syn cope, exercise blood pressure response (BPR), family history of sudden deat h (FHSD) and left ventricular wall thickness (LVWT). RESULTS During follow-up (3.6 +/- 2.5 years [range 2 days to 9.6 years]), 3 6 patients (9.8%) died, 22 of them suddenly. Two patients received heart tr ansplants. The six-year SD-free survival rate was 91% (95% confidence inter val [CI] 87% to 95%). In the Cox model, there was a significant pairwise in teraction between FHSD and syncope (p = 0.01), and these were subsequently considered together. The multivariate SD risk ratios (with 95% CIs) were 1. 8 for BPR (0.7 to 4.4) (p = 0.22); 5.3 for FHSD and syncope (1.9 to 14.9) ( p = 0.002); 1.9 for NSVT (0.7 to 5.0) (p = 0.18) and 2.9 for LVWT (1.1 to 7 .1) (p = 0.03). Patients with no risk factors (n = 203) had an estimated si x-year SD-free survival rate of 95% (95% CI 91% to 99%). The corresponding six-year estimates (with 95% CIs) for one (n = 122); two (n = 36) and three (n = 7) risk factors were 93% (87% to 99%), 82% (67% to 96%) and 36% (0% t o 75%), respectively. Patients with two or more risk factors had a lower si x-year SD survival rate (95% CI) compared with patients with one or no risk factors (72% [56% to 88%] vs. 94% [91% to 98%]) (p = 0.0001). CONCLUSIONS This study demonstrates that patients with multiple risk factor s have a substantially increased risk of SD sufficient to warrant considera tion for prophylactic therapy. (C) 2000 by the American College of Cardiolo gy.