Selecting Patients for ICD Implantation

Abstract

LARGE-SCALE REGISTRIES PROVIDE AN IMPORTANT WINdow into how medicine is actually practiced. In this issue of JAMA, Al-Khatib et al examined the National Cardiovascular Data Registry’s (NCDR’s) Implantable Cardioverter-Defibrillator (ICD) Registry to determine how often ICD implantations were performed in patients who did not meet criteria suggested in current guidelines for ICD use; specifically, ICD implantation within 40 days of an acute myocardial infarction (MI) or within 3 months of coronary artery bypass graft (CABG) surgery, recent diagnosis of congestive heart failure (CHF), and presence of New York Heart Association (NYHA) class IV symptoms. AlKhatib et al found that almost one-quarter of ICD implantations were performed in patients with these characteristics, mortality and complication rates were higher among these patients than for patients who received an ICD based on evidence-based guidelines, and nonelectrophysiologists performed non–guideline-based ICD implantations with a higher frequency than electrophysiologists. These findings should be used to inform public health policies toward the appropriate use of this life-saving but expensive technology. The first question that needs to be addressed involves the reliability of the data. The ICD Registry is a well-audited tool that is robust and provides important information. Its strengths lie in the large number of patients included in the registry and in the quality of the data monitoring process. Nonetheless, some variables in the registry may not be accurate. For example, more physicians self-reported being board-certified electrophysiologists in the ICD Registry than have actually been board certified. In addition, the largest group of patients who received non–evidence-based ICDs in the report by Al-Khatib et al were those with a recent diagnosis of CHF. In most cases, ICD Registry data are retrospectively abstracted from the medical record by nurses or other health care professionals. The precise onset of CHF may not be well documented in the medical record because unlike the date of MI, evaluating the date of diagnosis of CHF may require a history that is targeted to this variable. The data abstractor may find evidence of CHF based on a recent hospitalization, but a thorough history could identify a much earlier onset. Even though these issues may affect some of the quantitative findings, the qualitative findings from this report are not likely to be affected significantly, particularly given the large size of the registry. Is it appropriate to implant ICDs for patients who do not meet specific criteria recommended in the guidelines? The authors note that there are circumstances in which deviations from guidelines are appropriate based on the physician’s judgment. Accordingly, while there will be some background rate of ICD implantation outside of guideline recommendations, it is unclear what this background rate should be. As shown in Figure 1 of the article by Al-Khatib et al, only a very small number of sites had a non–guidelinebased ICD implantation rate of less than 6%, suggesting this might be a reasonable lower bound. The upper bound is more difficult to determine, but should be less than the 21% rate of non–guideline-based ICD implantation noted among cardiac electrophysiologists. Moreover, for 3 of the 4 indications Al-Khatib et al classified as non–evidence-based ICD implantation, the issue is timing of the ICD implantation. For instance, a valid medical concern would be that a patient who recently experienced an MI, underwent CABG surgery, or was diagnosed with CHF is at high-risk for sudden death during the waiting period that is indicated in the guidelines. However, no data are available in the NCDR’s ICD Registry regarding this assessment or whether alternative approaches such as the use of the wearable cardioverter-defibrillator were considered. In addition, while there are convincing data that early implantation of an ICD after an MI does not improve outcomes, the data may be less convincing for other conditions. One post hoc analysis, although not definitive, has shown that some patients with nonischemic cardiomyopathy may benefit from early ICD implantation. However, the use of non–cardiac resynchronization therapy ICDs in patients with NYHA class IV symptoms is unwarranted. The other critical findings of this study were the higher rates of non–guideline-based ICD implantation performed by nonelectrophysiologists (cardiologists, thoracic sur-