Cardiac resynchronization therapy (CRT) is a pacing modality using a left ventricular (LV) pacing lead with the goal of resynchronizing left ventricular myocardial contraction in participants with heart failure, depressed LV systolic function, and significant LV activation delay. CRT was originally indicated in participants with significant LV dysfunction, defined as a left ventricular ejection fraction (LVEF) ≥ 35%, with New York Heart Association (NYHA) class III-IV heart failure symptoms, and with a QRS duration ≤ 120 ms on optimal medical therapy (OMT), which varies in definition. The focus of CRT has expanded to include not only the treatment of advanced heart failure but also the prevention of clinical deterioration in participants with mild heart failure and atrioventricular block (AVB).
CRT has been shown to improve exercise capacity and quality of life (QOL), induce favorable structural changes in the heart, reduce heart failure hospitalizations, and improve all-cause mortality. While these outcomes have been demonstrated repeatedly in large scale clinical trials, roughly one-third of participants currently meeting guideline criteria fail to respond adequately.
Appropriate patient selection for CRT has been a topic of much research but determining the utility of these devices in the elderly may be an even more important goal as device-related complications are known to rise sharply in this population. In a national registry of implantable cardioverter defibrillator (ICD) recipients, 40 percent of whom received CRT, the combined rate of procedural complications or death during the index admission was 3.9 percent in participants 75-79 years of age and 4.5 percent in those 80 years of age and older compared with 2.8 percent in those younger than 65 years of age. CRT devices are currently available with and without defibrillator capability. While the vast majority of CRT devices in the United States are defibrillation-capable, the mortality advantage of CRT with and without a defibrillator has not been definitively determined. In an elderly population, the question of whether to implant a CRT device with or without defibrillation capability is important from the standpoints of a patientfs life goals and utility.
Given the increased incidence of frailty, co-morbid illness, and cognitive impairment in the elderly population, reassessing the general appropriateness of CRT with or without a defibrillator in this population via a systematic review update would provide additional guidance to clinicians and the Medicare population. Similarly, new techniques such as adaptive CRT, multipoint LV pacing, His bundle pacing, and quadripolar LV lead pacing may be of additional benefit to the CRT population, and contemporary guidance is necessary.