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Biventricular Pacing With or Without ICD
Study Questions:
What is the incremental value of an implantable cardioverter-defibrillator (ICD) in patients undergoing cardiac resynchronization therapy (CRT) for congestive heart failure (CHF)?
Methods:
In this single-center, observational study, outcomes of patients undergoing implantation of a CRT-pacemaker (CRT-P; n = 361) were compared with that of those receiving a CRT-defibrillator (CRT-D; n = 327). Patients underwent the procedure for medically refractory systolic CHF and a bundle branch block (BBB). In patients with a primary prevention indication (i.e., no sustained ventricular tachycardia [VT] or unexplained syncope), the decision to recommend a CRT-P versus CRT-D was left to the discretion of the physician. In general, a CRT-P was recommended for older, and more frail patients. Vital status of patients was determined by analysis of the national (Belgian) death registry. Mode of death was determined by accessing hospital records.
Results:
Patients in the CRT-P group were older (76 vs. 69 years), female (41% vs. 23%), more likely to be afflicted by comorbidities (such as atrial fibrillation, anemia, cachexia), and were less likely to be prescribed or be tolerant of beta-blockers and aldosterone-antagonists. The mean ejection fraction was higher in the CRT-P group (33% vs. 27%). Over a mean follow-up of 3 years, five patients (1.4%) in the CRT-P experienced either VT with syncope or ventricular fibrillation. In four of these patients, the episode was detected by remote monitoring, and patients were upgraded to a CRT-D. There were 75 deaths (21%) in the CRT-P and 38 (12%) in the CRT-D group, respectively (p < 0.001). Patients in the former group were more likely to die of noncardiac causes (p = 0.002). In addition to the above, in the CRT-P group, one patient died of electromechanical dissociation and another died suddenly.
Conclusions:
The authors concluded that the majority of deaths among patients who received CRT-P for systolic heart failure are due to noncardiac causes.
Perspective:
Patients who are referred for CRT for systolic heart failure and BBB are also candidates for an ICD for primary prevention of sudden death. However, some patients are recommended to undergo or may opt for a CRT-P as opposed to a CRT-D device. Factors included in the decision making process include age, frailty, patient expectation, amount of subcutaneous tissue (CRT-D device requires a larger pocket), and others. Since most of the deaths in the CRT-P group were due to non-cardiac causes, some may recommend pacing only. However, over a follow-up of about 3 years, 1-2% of CRT-P did experience potentially life-threatening ventricular arrhythmias. In the absence of guidance from large, randomized studies, it is prudent to pursue an individualized approach in selecting the type of device, considering the factors outlined above.
Keywords: Anemia, Arrhythmias, Cardiac, Atrial Fibrillation, Bundle-Branch Block, Cachexia, Cardiac Resynchronization Therapy, Death, Sudden, Defibrillators, Implantable, Heart Failure, Systolic, Mineralocorticoid Receptor Antagonists, Pacemaker, Artificial, Primary Prevention, Subcutaneous Tissue, Ventricular Fibrillation, Tachycardia, Ventricular
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