Reversible Chronotropic Incompetence in Early Cardiac Sarcoidosis Assessed by Serial Exercise Echocardiography

Cardiac sarcoidosis (CS) can cause conduction disturbances and heart failure. Chronotropic incompetence due to atrioventricular (AV) conduction abnormalities may represent an early and potentially reversible manifestation of CS.

A 62-year-old woman with suspected CS presented with exertional dyspnea and exercise-induced second-degree AV block. Despite preserved left ventricular systolic function at rest, cardiopulmonary exercise testing combined with exercise echocardiography revealed a severely impaired chronotropic response and inadequate cardiac output augmentation. ¹⁸F-fluorodeoxyglucose positron emission tomography showed focal septal myocardial uptake, and skin biopsy confirmed sarcoidosis. After corticosteroid therapy, the AV block resolved with improved heart rate response, cardiac output, and exercise tolerance.

Chronotropic incompetence due to reversible AV conduction delay may occur as an early manifestation of CS and improve with timely corticosteroid therapy.

Serial exercise echocardiography quantifies chronotropic and hemodynamic recovery during corticosteroid therapy and aids early detection of cardiac sarcoidosis.