Which patients with chronic heart failure should be referred for CRT‑D implantation? Practical implications of current clinical research

Over the last decade, cardiac resynchronization therapy (CRT) has emerged as an important treatment modality in patients with heart failure. Primary prevention of mortality with implantable cardioverter-defibrillator (ICD) in patients with ischemic and nonischemic cardiomyopathy and left ventricular dysfunction (ejection fraction [EF] < or =35%) has become the standard of care. A growing number of patients with indications for ICD are also eligible for CRT, receiving resynchronization pacing-defibrillator devices (CRT-D). Randomized clinical trials have provided evidence that cardiac resynchronization therapy is beneficial in heart failure patients and contributes to a significant decrease in heart failure progression on top of administering optimal pharmacological therapy. Currently approved indications for CRT-D include utilizing this treatment modality in heart failure patients with New York Heart Association (NYHA) class III or IV, EF < or =35%, and QRS > or =120 ms. New data from MADIT-CRT (Multicenter Automatic Defibrillator Implantation Trial-Cardiac Resynchronization Therapy) document that patients with less advanced heart failure (ischemic cardiomyopathy in NYHA class I or II and nonischemic cardiomyopathy class II), EF < or =30%, and QRS > or =130 ms also benefit from CRT. These findings indicate that a more proactive approach should be considered regarding the management of heart failure patients with less advanced disease to decrease progression of heart failure with CRT-D therapy.