Background <p>“Athlete’s heart” refers to the physiological cardiac hypertrophy observed in competitive athletes, which reverts to normal after retirement from competition. However, few studies have examined long-term follow-up. This study investigated whether former college athletes with a history of an athlete’s heart have a higher risk of developing heart disease later in life and examined its association with angiotensin-converting enzyme (<i>ACE</i>) insertion (I)/deletion (D) polymorphisms.</p> Methods <p>A total of 980 participants (mean age, 52.0 ± 15.7 years) from the Juntendo University Alumni Study were analyzed. Information on Athlete’s heart during college and subsequent heart disease, including left ventricular hypertrophy, was obtained through self-administered questionnaires in 2018. The <i>ACE</i> I/D genotype was determined based on the rs4341 C/G polymorphism.</p> Results <p>Of all participants, 177 (18.1%) reported Athlete’s heart during college, and 15 (1.5%) were diagnosed with left ventricular hypertrophy later in life. Former athletes with Athlete’s heart had a 7.3-fold higher prevalence of left ventricular hypertrophy than those without such a history. Moreover, carriers of the D allele showed a further increased risk (odds ratio, 13.63; 95% confidence interval, 1.31–142.41).</p> Conclusions <p>These findings suggest that regular cardiac monitoring may be warranted to identify potential late-onset cardiac remodeling in former athletes with Athlete’s heart carrying the <i>ACE</i> D allele.</p>