Left ventricular wall thickness and the presence of asymmetric hypertrophy in healthy young army recruits: data from the LARGE heart study.

BACKGROUND: To use cardiovascular magnetic resonance to investigate left ventricular wall thickness and the presence of asymmetrical hypertrophy in young army recruits before and after a period of intense exercise training. METHODS AND RESULTS: Using cardiovascular magnetic resonance, the left ventricular wall thickness was measured in all 17 segments and a normal range was calculated for each. The prevalence of asymmetrical wall thickening was assessed before and after training and defined by a ventricular wall thickness ≥13.0 mm that was >1.5× the thickness of the opposing myocardial segment. Five hundred forty-one men (mean age, 20±2 years) were recruited, 309 underwent repeat scanning. Considerable variation in wall thickness was observed across the ventricle with progressive thickening on moving from the apex to base (P<0.001) and in the basal and midcavity septum compared with the lateral wall (11.0±1.4 versus 10.1±1.3 mm; P<0.001). Twenty-three percent had a maximal wall thickness ≥13.0 mm, whereas the prevalence of asymmetrical wall thickening increased from 2.2% to 10% after the exercise-training program. In those who developed asymmetry, the wall thickness/diastolic volume ration remained normal (0.09±0.02 mm⋅m(2)⋅mL(-1)), indicative of a remodeling response to exercise. CONCLUSIONS: In a cohort of healthy young white men, we have demonstrated that wall thickness frequently measures ≥13.0 mm and that asymmetrical wall thickening is common and can develop as part of the physiological response to exercise. A diagnosis of hypertrophic cardiomyopathy in young athletic men should, therefore, not be made purely on the basis of regional wall thickening.