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QUARTERLY FOCUS ISSUE: HEART RHYTHM DISORDERS: STATE-OF-THE-ART PAPER

Appropriate Evaluation and Treatment of Heart Failure Patients After Implantable Cardioverter-Defibrillator Discharge

Time to Go Beyond the Initial Shock

Joseph D. Mishkin, MD^_*, Sherry J. Saxonhouse, MD^_*, Gregory W. Woo, MD^_*, Thomas A. Burkart, MD^_*, William M. Miles, MD^_*, Jamie B. Conti, MD^_*, Richard S. Schofield, MD^_*, Samuel F. Sears, PhD and Juan M. Aranda, Jr, MD^_*,_*

^_* Division of Cardiovascular Medicine, University of Florida College of Medicine, Gainesville, Florida
Departments of Psychology and Cardiovascular Sciences, East Carolina University, Greenville, North Carolina

Manuscript received May 15, 2009; revised manuscript received June 25, 2009, accepted July 12, 2009.

^_* Reprints requests and correspondence: Dr. Juan M. Aranda, Jr, Division of Cardiovascular Medicine, University of Florida College of Medicine, 1600 SW Archer Road, Room M421, Gainesville, Florida 32610 (Email: arandjm{at}medicine.ufl.edu).

Multiple clinical trials support the use of implantable cardioverter-defibrillators (ICDs) for prevention of sudden cardiac death in patients with heart failure (HF). Unfortunately, several complicating issues have arisen from the universal use of ICDs in HF patients. An estimated 20% to 35% of HF patients who receive an ICD for primary prevention will experience an appropriate shock within 1 to 3 years of implant, and one-third of patients will experience an inappropriate shock. An ICD shock is associated with a 2- to 5-fold increase in mortality, with the most common cause being progressive HF. The median time from initial ICD shock to death ranges from 168 to 294 days depending on HF etiology and the appropriateness of the ICD therapy. Despite this prognosis, current guidelines do not provide a clear stepwise approach to managing these high-risk patients. An ICD shock increases HF event risk and should trigger a thorough evaluation to determine the etiology of the shock and guide subsequent therapeutic interventions. Several combinations of pharmacologic and device-based interventions such as adding amiodarone to baseline beta-blocker therapy, adjusting ICD sensitivity, and employing antitachycardia pacing may reduce future appropriate and inappropriate shocks. Aggressive HF surveillance and management is required after an ICD shock, as the risk of sudden cardiac death is transformed to an increased HF event risk.

Key Words: implantable cardioverter-defibrillator therapy • heart failure • appropriate shock • inappropriate shock

Abbreviations and Acronyms   ACEI = angiotensin-converting enzyme inhibitor   AF = atrial fibrillation   ATP = antitachycardia pacing   AV = atrioventricular   HF = heart failure   ICD = implantable cardioverter-defibrillator   NYHA = New York Heart Association   RV = right ventricular   SVT = supraventricular tachycardia   VF = ventricular fibrillation   VT = ventricular tachycardia