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Implantable Cardioverter Defibrillators Have Stood the Test of Time!

The implantable cardioverter-defibrillator (ICD) has been the mainstay therapy for the prevention of sudden cardiac death (SCD), and it is lifesaving in many patients with heart failure with a reduced ejection fraction (HFrEF).1,2 Nevertheless, some have questioned the role of the ICD in contemporary clinical practice arguing that randomized clinical trials of primary prevention ICDs were completed more than 15 years ago, and, as such, their findings may not apply to patients seen in today’s clinical practice.3,4 Others have highlighted the fact that medical therapies for HFrEF have evolved and, through their effect on SCD, have lessened the survival benefit of ICDs.5 Others have pointed to the neutral results of the DANISH trial (Danish Study to Assess the Efficacy of ICDs in Patients with Nonischemic Systolic Heart Failure on Mortality) concluding that primary prevention ICDs are not beneficial in patients with nonischemic dilated cardiomyopathy.6 Before one derives definitive conclusions about current outcomes of primary prevention ICDs in HFrEF, it is important to examine each of these arguments more closely. Although the argument that the pivotal randomized clinical trials of primary prevention ICDs were completed more than 15 years ago is correct, this argument seems to dismiss several studies published more recently showing survival benefit associated with the use of the ICD. Using patient-level data, 1 study showed that HFrEF patients receiving an ICD in clinical practice in the US have survival similar to patients who received an ICD in MADIT-II (Multicenter Automatic Defibrillator Implantation Trial-II) and SCD-HeFT (Sudden Cardiac Death in Heart Failure trial) and better survival than patients who received medical therapy only in those trials.7 Another study showed that Medicare beneficiaries with a left ventricular ejection fraction of 30% to 35% hospitalized for heart failure had better 3-year survival with an ICD than with no ICD.8 In several analyses, survival benefit was observed in association with the use of primary prevention ICDs among women, racial minorities, and patients with multiple comorbidities.9 A distinct contribution of these observational studies is shedding light on the role of primary prevention ICDs in patients not well represented in randomized clinical trials, including older patients, as many of these analyses were limited to Medicare beneficiaries. Given the limitations of observational studies and the small number of patients older than 75 years of age enrolled in the pivotal randomized clinical trials of ICDs, the question of whether the ICD is beneficial in older patients is of great importance. The 2017 American Heart Association/American College of Cardiology/Heart Rhythm Society guideline for the prevention of SCD has the following recommendation: “For older patients and those with significant comorbidities, who meet indications for a primary prevention ICD, an ICD is reasonable if meaningful survival of greater than 1 year is expected.”1,10 However, more data are needed on ICDs in older patients, especially those >80 years of age. © 2019 American Heart Association, Inc.