Chronotropic incompetence in a young adult: case report and literature review.

Chronotropic incompetence (CI) is the inability of heart rate response to meet metabolic demand. CI is associated with sinus node dysfunction, atrial fibrillation, or structural heart disease, and can lead to functional impairment. We report the case of a 34-year-old man with CI secondary to sinus node dysfunction who demonstrated significant improvement in functional capacity with rate-responsive pacing. Therapy for CI should be guided by the treatment of the underlying cause with consideration for rate-responsive pacing in symptomatic patients. The prognosis of CI is variable and dependent on underlying etiology.