Usefulness of ECG to differentiate apical hypertrophic cardiomyopathy from non-ST elevation acute coronary syndrome

Abstract

Objective: Apical hypertrophic cardiomyopathy (ApHCM) is a phenotypic variant of nonobstructive HCM. ApHCM is characterized by left ventricular hypertrophy involve the distal apex. The electrocardiographic character of ApHCM can mimic non-ST elevation acute coronary syndrome (NSTEACS) which triggers a series of studies and treatments that may be unnecessary. This study aimed to clarify the ECG differences between the two diseases.Methods: Initial electrocardiogram (ECG) recordings of 41 patients with ApHCM and 72 patients with NSTEACS were analyzed retrospectively. We analyzed the voltage of negative T (neg T) wave, R wave and the change of ST-segment in the 12-lead ECGs as well as the number of leads with neg T waves.Results: Across the 12-lead ECGs, the magnitude of R wave significantly differed between ApHCM and NSTEACS in 10 leads excluding leads aVR and V1. ApHCM was associated with a greater maximal amplitude of R wave in lead V5 (3.13±1.08 vs. 1.38±0.73, P=0.000). The magnitude of T wave significantly differed between ApHCM and NSTEACS in 10 leads excluding leads II and V1. ApHCM was associated with a greater maximal amplitude of neg T wave in lead V4 (0.85±0.69 vs. 0.35±0.23, P=0.000). The frequency of giant neg T (1mv or more) wave was higher in ApHCM (36.5% vs. 0%, P=0.000). The magnitude of ST-segment deviation significantly differed between ApHCM and NSTEACS in 10 leads excluding leads aVF and V2. ApHCM was associated with a greater maximal amplitude of ST-segment depression in lead V5 (0.19±0.07 vs. 0.03±0.06, P=0.000). The number of leads with neg T waves also differed between ApHCM and NSTEACS (6.75±1.42 vs. 6.08±1.51, P=0.046). The sum of R wave in lead V5, neg T wave in lead V6 and ST-segment depression in lead V4>2.585 mV identified ApHCM with 90.2% sensibility and 87.5% specificity, representing the highest diagnostic accuracy.Conclusions: Compared with NSTEACS patients, ApHCM patients presented higher R waves and neg T wave voltage as well as a greater ST-segment depression in the 12-lead ECGs.