Implantable cardioverter-defibrillators (ICDs) have emerged as an important treatment option for select patients with heart failure, those with reduced left ventricular function, and individuals at risk for cardiac arrest or sudden cardiac death. “For years, these devices have served as an effective means of stopping life-threatening abnormal heart rhythms,” explains Venu Menon, MD. Recommendations on ICD use in clinical practice have been provided in guidelines sponsored by the American College of Cardiology (ACC), the American Heart Association (AHA), Heart Rhythm Society (HRS), and the European Society of Cardiology. However, recent guideline updates are lacking because most clinical trials tend to focus on the effectiveness of ICDs that provide cardiac resynchronization therapy (CRT) rather than outcomes of non-CRT defibrillators.
“Although many patients have benefited from ICD implants, there are still groups who fall outside the standard guidelines for treatment,” says Dr. Menon. Smaller patient populations or unique circumstances are not typically provided with indications for treatment. As a result, guideline indications for ICD therapy are limited specifically to patients who would have been eligible for enrollment in clinical trials. “Clinicians are often asked to make decisions about ICD therapy for patients who were not included or who were poorly represented in prior clinical trials,” Dr. Menon says. “For these individuals, there are no specific indications for ICD therapy.”
Addressing an Important Need
In 2014, the ACC, HRS, and AHA released an expert consensus statement, published in the Journal of the American College of Cardiology, on ICD use in patients not included or not well represented in clinical trials. “The statement provides direction on ICD therapy that specifically targets patients who haven’t been included in existing guidelines,” says Dr. Menon, a co-author of the consensus statement. He notes, however, that the recommendations cannot account for all the nuances of care and should not replace careful clinical judgment.
Instead of serving as a comprehensive guideline, the consensus document offers statements on what is recommended and what is not (Table). It also provides statements on strategies that can be useful. Experts performed a comprehensive literature search and based their recommendations largely on subgroup analyses of randomized clinical trials, retrospective studies, analyses of large registries, and expert opinion. They ultimately developed a series of recommendations and provided explanations of the rationale for each one.
Assisting With Specific Situations
For the consensus statement, the writing group evaluated available data on four important situations for which ICD therapy might be beneficial among those who were not consistently included in trials. This included:
1) Use of ICDs in patients with an abnormal troponin not due to a myocardial infarction (MI).
2) Use of ICDs within 40 days after an MI.
3) Use of ICDs within the first 90 days after revascularization.
4) Use of ICDs in the first 9 months after initial diagnosis of non-ischemic cardiomyopathy.
The writing group also evaluated the utility of an atrial lead in patients requiring ICD therapy without CRT. In addition, recommendations were provided for specific scenarios in which CRT is not indicated or not desired and for cases in which physicians must choose between single- or dual-chamber ICDs.
Keeping an Eye on Goals
Dr. Menon says efforts are needed to learn more about the patients who can benefit from ICDs and the best ways to implement this therapy for special cases. “Our goal is to improve the consistency and overall quality among hospitals and healthcare providers so that we can leverage the benefits of ICD therapy to more patients who can benefit from it,” he says. “The current guidelines surrounding ICD use are rigid, but patient cases aren’t always black and white. This document provides assistance to clinicians so that they can determine when they might consider ICDs as a treatment option. It also can help clinicians justify the use of ICDs in cases when reimbursement comes into question.”
According to the consensus document, more research is needed. “Clinicians should continue to support registries for analysis of ICD implantation and support efforts to standardize electronic health records,” says Dr. Menon. It is also important to acknowledge that some patients who would benefit from ICD therapy do not receive counseling on the potential benefits of this treatment. Efforts are also needed to evaluate the effectiveness and value of ICDs and to ensure consistency among the various documents that clinicians use to guide therapy choices and reimbursement.
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