ICDs Often Not Given to Older Patients After Acute MI, Outcomes Suffer

Few Medicare beneficiaries with low ejection fraction (EF) receive implantable cardioverter-defibrillators (ICDs) within a year of having an acute MI, but those who do are less likely to die within 2 years, according to a study published in the June 23/30, 2015, issue of the Journal of the American Medical Association.

“Health system interventions that encourage close outpatient follow-up, improve communication and implementation of longitudinal care plans, and educate patients should be studied to assess whether they can effectively optimize ICD consideration and use,” write Sean D. Pokorney, MD, MBA, of Duke University Medical Center (Durham, NC), and colleagues.

The researchers linked information from the National Cardiovascular Data Registry’s Acute Coronary Treatment and Intervention Outcomes Network Registry-Get With the Guidelines to claims data from the Centers for Medicare & Medicaid Services. The study included 10,318 patients older than 65 years (median age 78 years) with an EF of 35% or lower at the time of MI who were treated at 441 US hospitals between January 2, 2007, and September 30, 2010. Most patients (65%) had an NSTEMI.

ICDs May Lessen Mortality

In the first post-MI year, 8.1% of patients received an ICD, with a median time from the index admission to implantation of 137 days. After adjustment for case mix across hospitals, implantation rates ranged from 4.8% among those in the tenth percentile to 11.5% among those in the ninetieth percentile.

On multivariate analysis, factors associated with a lower likelihood of receiving an ICD in the first year were older age, female sex, end-stage renal disease, diabetes, higher BMI, and prior stroke or cancer. Among the factors related to greater odds of implantation were having a cardiology follow-up within 2 weeks after discharge and being readmitted for heart failure or MI.

ICD implantation was associated with a lower rate of 2-year mortality (15.3 vs 26.4 deaths per 100 patient-years), a difference that remained after adjustment (HR 0.64; 95% CI 0.53-0.78). That relationship was not modified by patient age or sex and was consistent in various sensitivity analyses.

Post-MI Waiting Period, Age Appear to Be Obstacles  

Although ICDs are indicated for patients with low EF after an MI, they are not recommended within the first 40 days after the event. In DINAMIT, there was no benefit to ICD implantation early after MI.

The requirement to wait at least 40 days after an MI before implanting an ICD could be why so few are used, according to the authors, who note that “ICD consideration is susceptible to errors of omission during the transition of post-MI care between inpatient and outpatient care teams.”

But age could be a stumbling block as well, they say. “Although the incidence of MI and resultant ischemic cardiomyopathy increases with age, the benefit of primary-prevention ICDs remains controversial among older patients, as these patients were underrepresented in clinical trials,” they explain. “Uncertainties regarding ICD effectiveness, along with other considerations of treatment goals and procedural risk, may discourage ICD implantation among older adults.”

Supporting the effectiveness of ICDs in older post-MI patients, however, is the fact that the magnitude of the relative reduction in the risk of 2-year mortality in the current study (36%) is consistent with that seen in MADIT II (31%).

“Individualized shared decision making, taking into context the patient’s quality of life, treatment goals, and preferences, is critical, because ICD therapy may shift death from a sudden event to a more gradual and comorbid process,” the authors write. “Age alone should not be an exclusion for ICDs, and better risk prediction tools validated among older patients are needed.”

Another possible reason for the underuse of ICDs is the recovery of ventricular function after an MI. Although postdischarge measurements of EF were not available in this analysis, “a previous study showed low EF recovery rates, so this is unlikely to fully explain the very low ICD implantation rate observed in our study,” Dr. Pokorney and colleagues say.

Fragmented Healthcare System to Blame?

In an accompanying editorial, Robert G. Hauser, MD, of Abbott Northwestern Hospital (Minneapolis, MN), says that “even if the ICD implantation rate were twice what Pokorney et al found, it is concerning that so few potentially ICD-eligible elderly patients are undergoing implantation, especially considering that ICDs significantly improve survival.”

He acknowledges that it is possible that patient refusal, comorbidities, and negative publicity stemming from ICD recalls have a negative impact on use before pointing out the possibility “that many of these patients did not receive an appropriate ICD simply because they fell into a crevasse of the fragmented healthcare system in which overly burdened primary care physicians are expected to connect all the clinical and diagnostic information without the essential tools and necessary facts.”

The 40-day waiting period, in particular, “confounds the continuity-of-care process by placing a temporal barrier between the patient and the cardiac electrophysiologist, who has become the decision maker for ICD implantation in most communities,” Dr. Hauser says.

He suggests that a systemic change might be needed to address the problem. “Surely a performance improvement measure could be implemented so that all patients with an acute MI (STEMI or NSTEMI) could be followed up rigorously to ensure that an informed decision is made regarding primary prevention with an ICD and that optimal medical management has been prescribed,” he says.

Sources:

1. Pokorney SD, Miller AL, Chen AY, et al. Implantable cardioverter-defibrillator use among Medicare patients with low ejection fraction after acute myocardial infarction. JAMA. 2015;313:2433-2440.
2. Hauser RG. Underutilization of implantable cardioverter-defibrillators in older patients [editorial]. JAMA. 2015;313:2429-2430.

Disclosures:

• The study was supported by a grant from the Agency for Healthcare Research and Quality and by an independent investigator-initiated research grant from Boston Scientific to the Duke Clinical Research Institute. 
• Dr. Pokorney reports receiving grants or research support from AstraZeneca, Boston Scientific, and Gilead and serving on an advisory board for Janssen Pharmaceuticals. 
• Dr. Hauser reports no relevant conflicts of interest. 

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