Hypertrophic cardiomyopathy (HCM) is a leading cause of sudden cardiac death among athletes in the United States (1). The electrocardiogram (ECG) can be used for screening athletes to identify HCM (2-4); however, its routine use remains controversial due to false positives (5). We hypothesized that through systematic comparison of digital ECGs of HCM pa-A cohort of 1,124 athletes from the Stanford Sports Medicine program and 255 HCM patients from the Stanford Center for Inherited Cardiovascular Diseases underwent a resting 12-lead ECG. Each digital ECG was processed using the same algorithm. Continuous ECG characteristics were compared using Student t tests and dichotomous variables using chi-square tests. Because of differences in age, a secondary analysis with only HCM patients under 40 years of age was performed. Electrocardiographic characteristics that met the following criteria were considered the best at differentiating the 2 populations: 1) 10-fold greater prevalence in the HCM population; 2) prevalence <2% in athletes; 3) statistical significance of p < 0.001 when comparing athletes to HCM patients under 40 years of age. To determine the ability of these ECG characteristics to independently differentiate HCM patients from athletes, multivariate logistic regression analysis was performed. Athletes were on average 20 years of age, 65% male, and 24% African American. Patients with HCM were on average 51 years of age, 56% male, and 5.8% African American. Compared to athletes, patients with HCM had a higher resting heart rate (71 vs. 62 beats/min; p < 0.001), were more likely to have QRS duration >140 ms (12.5% vs. 0.09%; p < 0.001), a QTc interval >480 ms (14.6% vs. 0.4%; p < 0.001), left or right axis deviation, right bundle branch block, and right or left atrial abnormality. While 5.9% of patients with HCM had a left bundle branch block, none of the athletes had this finding. Any degree of T-wave inversion in leads V 4 , V 5 , or V 6 were more pronounced in the patients with HCM compared to athletes (38% vs. 0.8%; p < 0.001).of age, in 4 U.S. centers in 1985 (year 1). We stratified participants by year 5 (initial) BMI (kg/m 2 ): 18.5 to 24.9, 25 to 29.9, 30 to 34.9, $35. We further stratified participants by BMI change between years 5 and 25:increasing BMI (>2), stable BMI (#2), and fluctuating J A C C V O L . 6 5 , N O . 2 2 , 2 0 1 5 Letters J U N E 9 , 2 0 1 5 : 2 4 6 2 -8
