Abstract 18351: Prevalence, Clinical Significance and Relevance to Screening of Electrocardiographic Abnormalities in Hypertrophic Cardiomyopathy Versus Athlete's Heart

Abstract

Background: Hypertrophic cardiomyopathy is often in the differential diagnosis with athlete’s heart due to the partial overlap of ECG and echocardiographic abnormalities. This study assessed the prevalence, clinical significance and relevance to athletic screening of ECG abnormalities in hypertrophic cardiomyopathy (HCM) patients versus highly trained athletes.

Methods: We compared the ECG tracings of 247 HCM patients (73% males, mean age 39±14 years) with those of 133 highly trained athletes with augmented left ventricular (LV) mass (87% males, mean age 27±6 years), with the same age range (15-65 years) Based on the ECG findings, HCM patients and athletes were grouped as normal ECG (Group 1), isolated increase of QRS voltage (Group 2) and abnormal ECG showing ≥1 non-voltage criteria, including atrial enlargement, QRS left axis deviation, ST-segment or T-wave abnormalities, pathologic Q waves, and complete bundle branch block, regardless of QRS amplitude (Group 3).

Results: Group 1 ECG was found in 11/247 (4%) HCM patients vs 69/133 (52%) athletes (P<0.001); Group 2 ECG in 6 (2%) vs 53 (40%) (P<0.001) and Group 3 ECG in 230 (93%) vs 11 (8%) (P<0.001). Compared with HCM patients from Group 3, those from Group 1 and 2 had a lower maximal LV wall thickness (16±2 and 18±3 mm vs 21±5 mm; P=0.01) and a lower rate of either defibrillator implants (0 vs 17%) or major arrhythmic events (0 vs 6%) during a follow-up of 8±6 years. Combined voltage and non-voltage ECG abnormalities (Group 2 and 3) showed a sensitivity of 96% and a specificity of 52% for HCM, whereas non-voltage criteria alone (Group 3) increased the specificity to 92% (P<0.001) and reduced the sensitivity to 93% (P=0.35).

Conclusions: The ECG abnormalities of HCM and athlete’s heart overlap marginally. Unlike athletes, among HCM patients the ECG pattern of isolated increase of QRS voltages is uncommon and associated with a mild phenotype similarly to normal ECG. Interpreting as normal an isolated increase of QRS voltages almost doubles the ECG specificity, without significantly reducing sensitivity for HCM.