Background Physical activity is associated with ECG phenotypes that may overlap with those observed in conditions predisposing to sudden cardiac death. In 2005 the study group of sports cardiology produced guidelines to differentiate ECG changes likely to reflect physiological adaptation to exercise from those, which should prompt further investigations. The guidelines were updated in 2010 resulting in improved specificity in predominantly Caucasian cohorts (white athletes; WA). We sought to examine the performance of the 2010 guidelines in athletes of African/Afro-Caribbean origin (black athletes; BA).
Methods ECG of 923 male BA were evaluated to determine the proportion of individuals requiring further investigations based on the 2005, compared to the updated 2010 guidelines. The same evaluation was performed for a cohort of 1711 male WA and 209 patients with hypertrophic cardiomyopathy (HCM). In addition, the impact of “Refined Criteria” was examined, consisting of an upper limit of 470 msec for QTc and removing the following as abnormalities: (1) isolated voltage criteria for left atrial enlargement (LAE); (2) Isolated voltage criteria for right ventricular hypertrophy (RVH); (3) T-wave inversions (TWI) in V1/2 in WA and V1-V4 in BA.
Results Using 2005 guidelines, 549 BA (59.5%) met criteria for a positive ECG requiring referral for further investigations compared to 846 WA (49.4%). In comparison, 398 BA (43.1%) met criteria for a positive ECG using 2010 guidelines [predominantly due to TWI (22.3%), RVH (13.0%) and LAE 8.5%)] compared to 216 WA (12.6%) [predominantly due to TWI (3.0%), RVH (2.8%) and LAE (2.7%)]. All of the HCM patients met the criteria for a positive ECG, regardless of which guidelines were used. Using our “Refined Criteria,” the number of BA with a positive ECG was reduced to 161 (17.4%) and WA to 93 (5.4%). Five patients with HCM had isolated voltage criteria for LAE (2.4%); all were symptomatic apart from 1 (0.5%). Five patients with HCM had voltage criteria for LAE in combination with LVH but no other abnormalities on their ECG; all were symptomatic apart from 1 (0.5%).
Conclusions Updated guidelines significantly reduce the number of positive ECG results in WA, but less so in BA, emphasising the need for ethnicity specific criteria to be developed. Refining criteria based on physiological changes known to occur in athlete's heart results in further reduction in positive ECGs. Our findings in patients with HCM suggest that if found in isolation or in combination with voltage criteria for LVH alone, ECG evidence of LAE may be regarded as a physiological rather than pathological change.
- Athlete's heart