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Wearable cardioverter defibrillator benefitted high-risk patients after MI
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Use of a wearable cardioverter defibrillator may benefit patients who are at high risk for sudden cardiac arrest after MI, according to the results of an observational study.
According to background information, due to current guidelines and reimbursement practices patients must wait 40 days after a MI to receive an implantable cardioverter defibrillator if they did not undergo revascularization, or 3 months after a MI if they did undergo revascularization.
Andrew E. Epstein, MD, FAHA, FACC, FHRS, of the electrophysiology section of the department of cardiovascular medicine at University of Pennsylvania, and colleagues investigated whether a wearable cardioverter defibrillator (LifeVest, Zoll Medical) could benefit MI patients at risk for sudden cardiac arrest during the ICD waiting period.
Andrew E. Epstein
The researchers found patients prescribed the LifeVest within 3 months after MI (n=8,453; mean age, 62.7 years; 73% men) by searching Zoll Medical’s order database between Sept. 27, 2005, and July 13, 2011. They calculated patient use and compliance from data stored by the LifeVest monitor, and used clinical data from reimbursement-related documents supplied to Zoll Medical.
During the study period, 133 patients (1.6%) received 309 appropriate shocks, and 1.4% of all patients were successfully treated for sudden cardiac arrest. Of those receiving shocks, 91% were resuscitated from a ventricular arrhythmia. Among the shocked patients, 106 had a left ventricular ejection fraction ≤30%, 17 had a LVEF 30% to 35% and eight had a LVEF >36%. LVEF was not reported for two patients. Among the 38% of shocked patients who did not undergo revascularization, 84% had a LVEF ≤30% and 84% survived. Among the 62% of shocked patients who underwent revascularization, 77% had a LVEF ≤30% and 95% survived.
Three-quarters of shocked patients received treatment within the first month and 96% within the first 3 months. The median time from MI to shock was 16 days.
“Although some may argue that prescription of a defibrillator, whether an ICD or [wearable cardioverter defibrillator], is not appropriate during the waiting period post-MI as LV function improves, our study suggests that a small but not necessarily unimportant group of patients may derive benefit from defibrillation early after MI,” Epstein and colleagues wrote. Epstein is a member of the Cardiology Today Editorial Board.
Since a previous study had shown no survival benefit for home automated external defibrillator (AED) use in anterior-wall MI patients who were not candidates for ICD implantation, “having a wearable device that automatically provides monitoring and delivers electrical therapy without bystander intervention avoids some limitations of AED use and may be useful in that regard,” the researchers wrote.
Disclosure: See the full study for a list of the researchers’ relevant financial disclosures.
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