CONGRESS ABSTRACT

This case presents a 36-year-old healthy male who developed a rate-related left bundle branch block (LBBB) during a routine treadmill test for sports fitness. Despite a family history of ischemic heart disease and conduction abnormalities, the patient had no typical cardiovascular risk factors, was asymptomatic and had previously normal cardiac evaluations. Initial echocardiography showed normal left ventricular dimensions, preserved systolic function, and mildly reduced global longitudinal strain in limited segments, but no significant valvular lesions. Coronary CT revealed a malignant anomalous origin of the right coronary artery (RCA) from the left Valsalva sinus with an inter-arterial course and proximal narrowing, raising concern for potential ischemic risk. Subsequent functional testing aimed to exclude myocardial ischemia. A stress echocardiogram demonstrated the reappearance of LBBB at higher heart rates (over 150 bpm) without inducing symptoms or ischemic changes. Global systolic function remained preserved, and previously reduced strain segments normalized under stress. A stress Cardiac Magnetic Resonance (CMR) similarly showed no inducible ischemia, perfusion defects, or wall motion abnormalities. Additionally, a 24-hour Holter evaluation failed to identify arrhythmias or conduction issues at rest or mild exercise. Given the absence of ischemic findings, a conservative management strategy was adopted. The patient was advised to continue exercising while monitoring heart rate to avoid excessive elevations and to use potassium and magnesium supplements during intense activity. Annual stress echocardiograms and Holter monitoring, along with a stress CMR every five years, were recommended to detect any emerging ischemic or functional changes over time. This case underscores the importance of comprehensive evaluation in patients with exercise-induced conduction anomalies, particularly when structural coronary anomalies are identified. Despite the anatomically malignant RCA course, the patient remained free of ischemia and functional compromise. A careful, conservative follow-up strategy can safely balance the benefits of maintaining physical fitness against the potential, though currently unmanifested, risks associated with a high-risk coronary anomaly.