Underutilization of Implantable Cardioverter-Defibrillators in Older Patients

Clinical trials have demonstrated that sudden cardiac death after an acutemyocardial infarction (MI) can be prevented in patients at high risk by inserting an implantable cardioverterdefibrillator (ICD). Guidelines from the American Heart Association (AHA), American College of Cardiology (ACC), and theHeart Rhythm Society (HRS) state that ICD therapy is indicated for patients with left ventricular ejection fraction (EF) less than or equal to 35%due to priorMIwho are at least 40 days after MI and are in New York Heart Association Class (NYHA) II or III or in patients who have an EF less than or equal to 30% and are in NYHA Class I.1 These indications are supportedby thehighest levels of evidence (LevelA) and based in part on major clinical trials like the Multicenter AutomaticDefibrillator ImplantationTrial II2 andSuddenCardiac Death in Heart Failure Trial,3 which showed that ICD therapy in high-risk individuals with coronary artery disease results in a relative risk reduction for total mortality of between 20%and 30%. In a subsequent article published by the AHA, ACC, andHRS and endorsed by the AmericanGeriatrics Society, the only age-specific comorbidity that wouldmake a primary prevention ICD “rarely appropriate” was if a patient 90 years or older was in NYHA Class I.4 Why then are lifesaving ICDs so underused in these patients?5 Previous reports have shown that, at best, 50% of ICD-eligible patients in the United States and far fewer in Europe are receiving ICDs for primary prevention of sudden cardiac death after an MI.6 Moreover, studies have documented the low use of ICDs in women and black patients.7,8 In this issueof JAMA, Pokorneyandcolleagues9 report the results of their study examining the association between ICD implantation rates and mortality in Medicare beneficiaries treated at US hospitals between 2007 and 2010. Only 8.1% of 10 318 elderly patients (mean age, 78 years)with an EF of 35% or less received an ICD within 1 year of an acute MI. On average, patients who received an ICD had a significantly lower 2-year mortality than those who did not (15.3 vs 26.4 events per 100patient-years). Despite theobservational natureof the study and the concerns about confounding by indication, the absolutemortality reductionassociatedwith ICDusewas substantial, especially considering that fewother interventions reduce mortality by this magnitude. Patientsweremore likely to receive an ICD if theywere readmitted after the indexMIwith heart failure or recurrentMI or if they had cardiology follow-upwithin 2weeks of hospital discharge. The latter observation suggests that patients can benefit from at least 1 postdischarge visit with a cardiologist afteranacuteMI.Althoughtherewassomehospital-levelvariation in ICD implantation rates, none of the discharging hospitals, including academic centers, implanted ICDs inmore than 16% of ICD-eligible patients. The guidelines for ICD implantation do not differentiate between ST-segmentMI (STEMI) and non–ST-segment elevationMI (NSTEMI). In thisstudy,65%ofpatientshadanNSTEMI. In their univariable comparison, Pokorney and colleagues9 found that patients who received an ICD within 1 year were more likely to have presented initially with a STEMI, were younger and male, and had larger infarcts. This observation raises thequestionofwhetherpatientswithNSTEMIarebeing treated differently after hospital discharge. For instance, is it possible that less attention is beinggiven to theelderlywoman whohasasmallNSTEMIcomparedwith themiddle-agedworking man who presents with a STEMI and shock? These issues deserve further inquiry. The authors acknowledge that their study has certain limitations. One important limitation relates to assessment of recovery of left ventricular function after hospital discharge. Left ventricular function was measured only during the index hospitalization, and postdischarge EF data were not available. Citing a report published in 2001,10 Pokorney et al9 suggest that it is unlikely that many patients did not receive an ICD because their EF had improved and no longer met criteria. However, the era of catheter-based rapid reperfusion for MI was well under way during the period of their study (2007-2010), and the authors cannot exclude the possibility that a significant number of patients in this cohort did not require an ICD because their left ventricular function had improved (EF was >35%). Nonetheless, even if the ICD implantation ratewere twice what Pokorney et al9 found, it is concerning that so few potentially ICD-eligible elderly patients are undergoing implantation, especially considering that ICDs significantly improve survival. It is possible that someolder patientsmay refuse ICD therapy for personal reasonsor because comorbidities suchas end-stage kidney disease or advanced frailty were considered inthedecisionregardingICDimplantation.Moreover, ICDs have had their share of recalls, adverse events such as inappropriate shocks, and negative publicity. However, a possible scenario is that many of these patients did not receive an appropriate ICD simply because they fell into a crevasse of the fragmented health care system in which overly burdened primary care physicians are expected to connect all the clinical and diagnostic informaRelated article page 2433 Opinion