Moderate Exercise Linked to Misdiagnosis of Structural Heart Disease

Exercise-related cardiac remodeling, or “athlete’s heart,” is not confined to athletes but can also appear in adults who get moderate levels of exercise and could be misdiagnosed as cardiac dilatation or hypertrophy, according to the results of a recent study.

High-endurance athletes often have enlarged hearts with thicker walls and larger chambers, but little data exist on what level of exercise is necessary to produce these effects.
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To further understand the relationship between cardiac parameters and physical activity, the researchers recruited 1096 adults who did not have cardiovascular disease at baseline.

The study participants underwent cardiac magnetic resonance imaging to determine biventricular volumes and function and completed questionnaires about how many hours of physical activity they achieve per week.

Overall, 8% of the cohort reported engaging in no regular exercise, 41% reported light activity, 35% reported moderate activity, and 16% reported 5 or more hours of exercise per week.

The analysis showed that higher physical activity levels were associated with increased left ventricular mass and elevated left and right ventricular volumes.

Participants who engaged in 3 to 5 hours of weekly physical activity also had signs of athlete’s heart: biventricular dilatation with an increase in stroke volumes.

“Biventricular dilatation with an increase in [stroke volumes] are features of the athletic heart, but our findings suggest that this pattern may occur with as little as 3 to 5 hours exercise per week, and >5 hours exercise is associated with a high proportion of adults outside published normal ranges,” the authors wrote.

“Our findings suggest that the interpretation of volumetric parameters when investigating low-risk adults should consider each patient’s activity level as well as the conventional covariates of age, sex, and body surface area to avoid misdiagnosis of structural heart disease.”

—Amanda Balbi

Reference:

Dawes TJW, Corden B, Cotter S, et al. Ventricular structure and function: moderate physical activity in healthy adults is associated with cardiac remodeling. Circ Cardiovasc Imaging. 2016;9(8):e004712. doi:10.1161/CIRCIMAGING.116.004712.