Analysis of 7,326 adults revealed that each 10-beat-per-minute increase in resting heart rate corresponded to 25% higher odds of developing atrial cardiopathy—structural changes in the heart's upper chambers detected by electrocardiogram. Participants with heart rates ≥100 bpm showed 76% higher odds of atrial cardiopathy, while those ≤50 bpm had 39% lower odds. During 13.8 years of follow-up, individuals with both elevated heart rate and atrial cardiopathy faced a striking 4.11-fold increase in mortality risk compared to those with neither condition. This finding adds crucial nuance to cardiovascular risk assessment, suggesting that resting heart rate—easily measured in any clinical setting—may serve as an early indicator of atrial structural damage before overt heart disease develops. The dose-response relationship between heart rate and atrial changes provides a quantifiable target for intervention. However, this observational study cannot establish causation, and the predominantly older cohort may limit generalizability to younger adults. As an unreviewed preprint, these findings require peer validation before clinical application, though they align with emerging evidence linking elevated resting heart rate to multiple cardiovascular pathways beyond simple fitness markers.