A Critical Appraisal of Implantable Cardioverter-Defibrillator Therapy for the Prevention of Sudden Cardiac Death

Abstract

The indications for implantable cardioverter-defibrillators (ICDs) for the prevention of sudden cardiac death have rapidly expanded over the past 10 years. Clinical trial data have quickly been implemented into guidelines without critical reassessment of the strengths and limitations of the evidence. ICD therapy has inherent risks including infection, unnecessary shocks, potential for proarrhythmia, device malfunction, highly publicized manufacturer advisories, and procedural complications, which can adversely affect morbidity and quality of life. A reappraisal of the benefits and potential hazards of ICD therapy will enable physicians to a have a more mutually informed and balanced dialogue with their patients.

Primary prevention with ICDs, are we on the right track?

“…This issue is discussed at length by Tung et al and the interested reader is referred to that paper. 5 In conclusion, there is a growing awareness that ICD implant for primary prevention in patients with low LVEF should be reconsidered. Some refer to it as 'a bridge to far', 4 others question that current guidelines are 'not honest' to our patients.…”

“…[4][5][6] Since the vast majority of ICD recipients are primary prevention patients and since the growth in ICD use is based solely on prophylactic implants, we will briefly touch upon the most important issues.…”

“…Moreover, the patients included in the primary prevention trials experiencing benefit from ICD therapy had a significantly lower LVEF than the value that appeared in the guidelines. 5,6 The 2006 ACC/AHA/ ESC guidelines adapted a cut-off value of <40% (not relevant to any of the primary prevention trials! ), 8 but the 2008 ACC/AHA/HRS guidelines abandoned a single cut-off value and brought it back to specific patient groups (still with a higher LVEF than actually studied!).…”

“…16 The latter included shocks for rapid ventricular tachycardia which, as often thought or argued, is not similar to sudden death. 5 An important question to address is whether the lower event rate in these latter trials is in part explained by a lower than anticipated arrhythmia risk because the infarcts are PCI treated? And if so that would simply mean that nowadays PCI-treated infarcts carry a lower than anticipated arrhythmia risk in the long term.…”

Primary prevention with the ICD in clinical practice: not as straightforward as the guidelines suggest?

“…Recently, there has been a reappraisal of benefits and potential hazards of ICD therapy. 4 The purpose of this paper is to reflect on the guidelines considering known and potential risk factors that may help in risk stratification in clinical practice.…”