Results of numerous clinical trials support the use of cardiac resynchronization therapy (CRT) for treatment of moderate to severe heart failure in patients with cardiac dyssynchrony. Commercial approval of various CRT devices has led to a growing number of patients receiving this form of therapy. Patients with implanted CRT devices require specific attention to detect adverse events related to the device, detect failure to respond to therapy, and optimize device function. Interaction between the primary care physician, cardiologist, heart failure specialist, and electrophysiologist/ implanting physician is necessary to accomplish these goals. Recognizing the signs and symptoms of adverse events or suboptimal response allows the primary care physician to alter drug therapy or, when appropriate, refer the patient to the heart failure specialist or electrophysiologist for optimization of CRT device programming or further intervention.