Exercise-induced quantitative microvolt T-wave alternans in hypertrophic cardiomyopathy

- Hypertrophic cardiomyopathy is the leading cause of SCD in young adults and athletes.
- Patients were stratified as high-risk and low-risk groups per Maron score risk factors.
- High levels of microvolt T-wave alternans identified high-risk patients.
- Higher TWA values were associated with isolated major risk factors for SCD.

Background/PurposePatients with hypertrophic cardiomyopathy (HCM) have elevated risk for sudden cardiac death (SCD). Our study aimed to quantitatively characterize microvolt T-wave alternans (TWA), a potential arrhythmia risk stratification tool, in this HCM patient population.MethodsTWA was analyzed with the quantitative modified moving average (MMA) in 132 HCM patients undergoing treadmill exercise testing, grouped according to Maron score risk factors as high-risk (H-Risk, n = 67,), or low-risk (L-Risk, n = 65, without these risk factors).ResultsTWA levels were much higher for the H-Risk than for the L-Risk group (101.40 ± 75.61 vs. 54.35 ± 46.26 μV; p < 0.0001). A 53 μV cut point, set by receiver operator characteristic (ROC), identified H-Risk patients (82% sensitivity, 69% specificity).ConclusionsHigh TWA levels were found for hypertrophic cardiomyopathy patients. Abnormal TWA associated with major risk factors for SCD: non-sustained ventricular tachycardia on Holter (p = 0.001), family history of SCD (p = 0.006), septal thickness ≥30 mm (p < 0.001); and inadequate blood pressure response to effort (p = 0.04).