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Sudden death in hypertrophic cardiomyopathy: identification of high risk patients
P M Elliott1, J Poloniecki, S Dickie
1Department of Cardiological Sciences, St. George's Hospital Medical School, London, United Kingdom. pelliott@sghms.ac.uk
Insights
Identifying hypertrophic cardiomyopathy (HCM) patients at high risk of sudden death (SD) is crucial. Multiple risk factors, including family history of sudden death and syncope, significantly increase SD risk in HCM patients.
Area of Science:
- Cardiology
- Genetics
- Clinical Medicine
Background:
- Assessing sudden death (SD) risk in hypertrophic cardiomyopathy (HCM) is challenging due to low mortality rates.
- Conventional analysis of multiple clinical risk markers for SD is problematic.
- This study investigates noninvasive risk markers using a referral center registry.
Purpose of the Study:
- To identify patients with hypertrophic cardiomyopathy (HCM) at high risk of sudden death (SD).
Main Methods:
- Studied 368 patients (14-65 years old) with HCM.
- Assessed five risk variables: nonsustained ventricular tachycardia (NSVT), syncope, exercise blood pressure response (BPR), family history of sudden death (FHSD), and left ventricular wall thickness (LVWT).
- Utilized Cox regression models for multivariate analysis.
Main Results:
- During follow-up, 22 of 368 patients experienced sudden death (SD).
- The six-year SD-free survival rate was 91%.
- Key predictors of SD included the combination of FHSD and syncope (risk ratio 5.3), LVWT (risk ratio 2.9), and NSVT (risk ratio 1.9). Patients with two or more risk factors had a significantly lower six-year SD survival rate (72%) compared to those with one or no risk factors (94%).
Conclusions:
- Multiple risk factors substantially increase SD risk in HCM patients.
- Patients with multiple risk factors warrant consideration for prophylactic therapy.
- FHSD and syncope interaction is a significant predictor of SD in HCM.
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 referral center registry to investigate a smaller number of generally accepted noninvasive risk markers.
Methods:
We studied 368 patients (14 to 65 years old, 239 males) with HCM. There were five variables: nonsustained ventricular tachycardia (NSVT), syncope, exercise blood pressure response (BPR), family history of sudden death (FHSD) and left ventricular wall thickness (LVWT).
Results:
During follow-up (3.6+/-2.5 years [range 2 days to 9.6 years]), 36 patients (9.8%) died, 22 of them suddenly. Two patients received heart transplants. The six-year SD-free survival rate was 91% (95% confidence interval [CI] 87% to 95%). In the Cox model, there was a significant pairwise interaction 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 six-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% to 75%), respectively. Patients with two or more risk factors had a lower six-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 factors have a substantially increased risk of SD sufficient to warrant consideration for prophylactic therapy.