Medical Research: What is the background for this study?
Dr. Pokorney: About 350,000 people die of sudden cardiac death in the US each year. Patients who have weakened heart function, particularly those with heart muscle damage as a result of a heart attack, are more likely to experience sudden cardiac death. Defibrillators have been around since the 1980s, and have prolonged countless lives. A previous study showed that 87% of patients who had a cardiac arrest were eligible for an implantable-cardioverter defibrillator (ICD) beforehand but did not get an ICD implanted prior to their arrest. The timing of ICD implantation is critical, as studies have not found a benefit to ICD implantation early after myocardial infarction (MI). Guidelines recommend primary prevention ICD implantation in patients with an EF ≤ 35% despite being treated with optimal medical therapy for at least 40 days after an MI. Given the need to wait for at least 40 days after an MI, ICD consideration is susceptible to errors of omission during the transition of post-MI care between inpatient and outpatient care teams. Also, the benefit of ICDs remains controversial among older patients, as these patients were underrepresented in clinical trials.
Medical Research: What are the main findings?
Dr. Pokorney: We looked at Medicare patients discharged from US hospitals after a heart attack between 2007 and 2010. We focused on those patients who had weak heart function, and this left us with a little over 10,300 patients from 441 hospitals for our study. This was an older patient population with a median age of 78 years. We looked to see how many of these patients got an ICD within the first year after MI, and how many patients survived to 2 years after their heart attack. Only 8% of patients received an ICD within 1 year of their heart attack. ICD implantation was associated with a third lower risk of death within 2 years after a heart attack, and this was consistent with the benefit that were seen in the randomized clinical trials. Importantly, 44% of the patients in our study were over 80 years old, and we found that the relationship between ICD use and mortality was the same for patients over and under age 80 years. Increased patient contact with the health care system through early cardiology follow-up or re-hospitalization for heart failure or MI was associated with higher likelihood of ICD implantation. Rates of ICD implantation remained around 1 in 10 patients within 1 year of MI even among patients with the largest heart attacks and the weakest hearts (lowest ejection fractions), who were least likely to have improvement in their heart function over time. Similarly, even after excluding patients at highest risk for non-arrhythmic death (prior cancer, prior stroke, and end stage renal disease), ICD implantation rates remained around 1 in 10 patients.
Medical Research: What should clinicians and patients take away from your report?
Dr. Pokorney: The post-MI care transition is a point of vulnerability, since there is an obligate 40-day waiting period between the inpatient MI and when the patient is eligible for the therapy. Our results found that in an older patient population ICDs were associated with the same amount of benefit as was seen in patients in the randomized trials with average ages in their 60s. This emphasizes that age alone should not be a contraindication to ICD implantation, and current rates of ICD use in patients after MI are too low. The decision to implant an ICD certainly needs to be individualized based on a patient’s quality of life, treatment goals, and preferences, but it is important for providers to engage older patients in a shared decision making process. Patients need to take an active role in their care by ensuring that they schedule and attend outpatient appointments, as well as making sure that their providers are aware of what happened to them during recent hospitalizations.
Medical Research: What recommendations do you have for future research as a result of this study?
Dr. Pokorney: Health system interventions that encourage close outpatient follow-up, improved communication and implementation of longitudinal care plans, and better patient education should be studied to assess whether they can effectively optimize ICD consideration and use. Better models are needed to be able to predict the patients at highest risk of arrhythmic death, who would benefit from an ICD, compared to patients at risk for non-arrhythmic death, who would be less likely to benefit from an ICD. This would help providers refine patient selection towards those patients who are most likely to benefit from an ICD. Finally, further research is needed to better understand individualized patient risk tolerance, as well as how patients think through the trade-offs associated with ICD therapy. Better insight into these issues would allow providers to assist with the shared decision-making process regarding ICD implantation.
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(24):2433-2440. doi:10.1001/jama.2015.6409.
Sean D. Pokorney, MD, MBA, Division of Cardiology, Duke University Medical Center, & Duke Clinical Research Institute, Durham, North Carolina (2015). ICD Implantation Rates Too Low In Elderly