Electrocardiograms showing marked repolarization abnormalities in young athletes may predict their subsequent development of heart disease, according to Italian researchers.
“Contrary to previous reports describing such ECG patterns as innocent manifestations of 'athlete's heart' without adverse clinical consequences, the present study shows that these abnormal ECGs may represent the initial expression of genetic cardiac disease, preceding by many years phenotypic expression and adverse clinical outcomes,” wrote Dr. Antonio Pelliccia from the Institute of Sports Medicine and Science, Italian National Olympic Committee, Rome, and colleagues (N. Engl. J. Med. 2008;358:152-61).
The study included high-level athletes from the Italian Institute of Sports Medicine and Science database, all of whom are required by law to undergo preparticipation screening to rule out the presence of cardiovascular disease.
Of 12,880 athletes screened at the institute between 1979 and 2001, 81 were identified as having sufficient data showing marked repolarization abnormalities without evidence of structural heart disease, over a mean 10 years of serial clinical, ECG, and echocardiographic studies. A control group of 229 athletes of similar age, sex, and duration of follow-up was also selected from the same database. Marked repolarization abnormalities were defined as inverted T waves of 2 mm or more in depth in at least three leads (exclusive of standard lead III), and predominantly in the anterior and lateral precordial leads V2 through V6.
The 81 subjects in the study group included 63 men and 18 women, with a mean age of 23 years at their initial evaluation and 32 years at their most recent assessment. They were most commonly involved in soccer, rowing or canoeing, track and field, swimming, and cycling. They had participated in regular training and competition for a mean duration of 12 years, and 70% had achieved recognition at national or international events, including 14 who had participated in the Olympic Games. Among the 229 control subjects there were 157 men and 72 women who were a mean age of 22 years at initial evaluation. They participated in rowing or canoeing, soccer, water polo, track and field, shooting, and judo, and 80% had reached national or international levels of competition.
In the study group of 81 subjects with abnormal ECGs, evidence of cardiomyopathy developed in 5 (6%), and evidence of other cardiovascular disorders developed in 6 (7%) during the follow-up period, for a total of 11 subjects (14%), reported the authors. Among the five with evidence of cardiomyopathy, one died at age 24 years (1 year after the initial evaluation) from clinically undetected arrhythmogenic right ventricular cardiomyopathy.
Clinical and phenotypic features of hypertrophic cardiomyopathy developed in three other subjects (at ages 27, 32, and 50 years), including one who survived a cardiac arrest after 16 years of follow-up. The fifth athlete developed dilated cardiomyopathy over a 9-year follow-up.
Among the other six athletes in the study group who developed other cardiovascular conditions, there was systemic hypertension in three, atherosclerotic coronary artery disease (requiring bypass grafting) in one, myocarditis in one, and supraventricular tachycardia (requiring radiofrequency ablation) in one. The remaining 70 (86%) subjects in the study group had unremarkable clinical courses.
In contrast, there was no evidence of cardiomyopathy in any of the athletes in the control group over an average of 9 years of follow-up, and only four (2%) had evidence of other cardiovascular disorders. These included myocarditis in one athlete at age 19 years, 1 year after the initial evaluation; pericarditis in one athlete at age 28 years, 2 years after the initial evaluation; and supraventricular tachycardia in two athletes, identified after 2 and 3 years of follow-up.
“The negative predictive value of a normal ECG was 100% to exclude the development of cardiomyopathy and 98% to exclude the development of any cardiac abnormalities,” said the authors. “The positive predictive value of an abnormal ECG was 6% for cardiomyopathy and 14% for any cardiac condition.”
Although they noted that ECGs showing marked repolarization abnormalities “may be useful for identifying athletes at risk for the subsequent development of structural heart disease,” they suggested that such findings “underscore the importance of greater diagnostic scrutiny and continued clinical surveillance.” Serial ECG alone may not be sufficient for such surveillance, they added, suggesting “echocardiography and selective additional testing are necessary to clarify the cardiac diagnosis.” On the other hand, a normal ECG “can be regarded as reasonably reliable evidence to exclude the presence of potentially lethal cardiac disease,” they concluded.