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

Area of Science:

• Cardiology
• Electrophysiology
• Medical Diagnostics

Background:

• Hypertrophic cardiomyopathy (HCM) is associated with an increased risk of sudden cardiac death (SCD).
• Microvolt T-wave alternans (TWA) is being investigated as a potential tool for arrhythmia risk stratification in HCM patients.

Purpose of the Study:

• To quantitatively characterize microvolt T-wave alternans (TWA) in patients with hypertrophic cardiomyopathy (HCM).
• To assess the association between TWA levels and established risk factors for sudden cardiac death (SCD) in HCM.

Main Methods:

• Quantitative modified moving average (MMA) analysis of TWA was performed in 132 HCM patients during treadmill exercise testing.
• Patients were categorized into high-risk (H-Risk, n=67) and low-risk (L-Risk, n=65) groups based on Maron score risk factors.

Main Results:

• TWA levels were significantly higher in the H-Risk group compared to the L-Risk group (101.40±75.61 μV vs. 54.35±46.26 μV; p<0.0001).
• A TWA cut-off value of 53 μV, determined by receiver operator characteristic (ROC) analysis, identified H-Risk patients with 82% sensitivity and 69% specificity.

Conclusions:

• Elevated TWA levels are prevalent in HCM patients.
• Abnormal TWA is significantly associated with major SCD risk factors including non-sustained ventricular tachycardia, family history of SCD, marked septal thickening, and inadequate blood pressure response to exercise.