A 60-year-old man was admitted to the hospital with an inferior ST-segment-elevation MI, having arrived an hour after the onset of chest pain. He underwent primary PCI (door-to-balloon time, 30 minutes) and had no signs of heart failure. However, an echocardiogram performed the next day revealed multiple regional wall-motion abnormalities and a left ventricular ejection fraction of 33%.<\/p>\n
The doctors recommended that the patient wear a Zoll LifeVest for 90 days<\/a> and then return for a repeat assessment of his LVEF to determine whether he may benefit from an ICD. The patient was told that their practice routinely uses the LifeVest during this period after an MI for all patients with a depressed LVEF, until they can be assessed further.<\/p>\n Questions:<\/strong><\/p>\n 1. Does your institution use the LifeVest strategy routinely during the waiting period after an MI?<\/p>\n 2. What evidence do you use to support or eschew the strategy?<\/p>\n Response:<\/strong><\/p>\n James Fang, MD<\/a><\/p>\n October 3, 2012<\/em><\/p>\n Mortality risk is high during the first few months after acute MI<\/a>. Routine implantation of an ICD in high-risk patients after acute MI does not lower their overall mortality risk but does reduce the risk for arrhythmia-related death (see the DINAMIT trial<\/a>).<\/p>\n It is on this basis that some recommend the LifeVest as \u201cbridge\u201d therapy during this high-risk period. The LifeVest may be particularly attractive because, although it cannot reliably address bradyarrhythmias, it is not invasive like an ICD. Also, the risk for sudden death after MI decreases with time-dependent improvements in LVEF from revascularization and meds, and the LifeVest does not commit a patient to potentially unnecessary \u201cpermanent\u201d therapy. However, even though the vest may prevent sudden death from arrhythmia, it may not reduce overall mortality risk, given that the extent of the acute infarction may be the key determinant in the patient\u2019s outcome (again, see DINAMIT).<\/p>\n The electrophysiologists at my institution will offer the LifeVest to post-MI patients who appear to have, in addition to a low LVEF, major risk factors for sudden cardiac death (e.g., significant nonsustained ventricular arrhythmias, heart failure, inability to tolerate meds due to bradycardia or hypotension) during the first 40 days after acute MI, when ICD implants are not covered by CMS reimbursement. However, no randomized data support this practice; nor,\u00a0arguably, does the DINAMIT trial. To my knowledge, the largest published study of the LifeVest<\/a> is from an observational cohort.<\/p>\n Our electrophysiology service is not routinely asked to provide post-MI assessment of risk for SCD; in general, that remains the purview of our CCU faculty.\u00a0 Some institutions pursue further risk stratification with Holter monitoring, heart-rate variability (HRV) testing, electrophysiology studies, signal-averaged EKG, etc.\u00a0Notably, in the DINAMIT trial, additional factors (beyond LVEF) were used to identify patients at high risk for SCD (e.g., depressed HRV and increased heart rate).<\/p>\n Finally, after an acute MI, medical therapy must be optimized (statin, beta-blocker, ACE inhibitor, aldosterone antagonist), and LV function should be reassessed over time.<\/p>\n