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.