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Event rate low in patients with newly diagnosed cardiomyopathy using wearable cardioverter defibrillator
In a retrospective, single-center study of patients with newly diagnosed cardiomyopathy, use of a wearable cardioverter defibrillator was associated with a low event rate.
Researchers analyzed 525 patients with newly diagnosed ischemic (n = 271) or nonischemic (n = 254) cardiomyopathy who received a wearable cardioverter defibrillator (LifeVest, Zoll Medical) for protection against sudden cardiac death while waiting for re-evaluation of cardiac function at the University of Pittsburgh Medical Center between June 2004 and May 2015.
The primary outcome was appropriate wearable cardioverter defibrillator therapy.
Median wear time was 61 days (interquartile range, 25-102) and 22 hours per day (interquartile range, 17-23).
During 56.7 patient-years of follow-up, no patients with nonischemic cardiomyopathy received an appropriate shock, and 1.2% received an inappropriate shock, Madhurmeet Singh, DO, from the Heart and Vascular Institute at the University of Pittsburgh, and colleagues wrote.
Among patients with ischemic cardiomyopathy, during 46.7 patient-years of follow-up, six (2.2%) received an appropriate shock, all of whom were men with QRS duration greater than 120 ms, and two (0.7%) received an inappropriate shock, Singh and colleagues found.
Of the six patients receiving an appropriate shock, five survived the episode and four survived to hospital discharge, they reported.
“Despite these low rates of appropriate [wearable cardioverter defibrillator] discharges, [wearable cardioverter defibrillator] prescriptions increased significantly during our 10-year experience,” Singh and colleagues wrote.
Andrew E. Epstein, MD
In a related editorial, Andrew E. Epstein, MD, from the electrophysiology section of the division of cardiovascular medicine at the University of Pennsylvania, wrote that the low event rate is consistent with that in other studies, and that in studies of patients with MI, the cost of the wearable cardioverter defibrillator was less than $100,000 per quality-adjusted life-year gained, provided that the rate of cardiac arrest in the first month after MI was 1.163% or more.
Complicating matters, however, is that “there were no ‘entry criteria’ for who should be prescribed a [wearable cardioverter defibrillator]. Rather, the decision was made on the basis of clinical judgment and ‘gut feeling’ of perceived risk,” Epstein, a member of the Cardiology Today Editorial Board, wrote.
Because a large randomized controlled trial in this population is unlikely given the low event rates, “we must rely on data such as that presented by Singh et al and make our decisions at the bedside,” Epstein concluded. – by Erik Swain
Disclosure: Singh reports no relevant financial disclosures. Several other researchers report receiving research support from Boston Scientific, Medtronic and St. Jude Medical. Epstein reports receiving research grants from Biotronik, Boston Scientific, Medtronic and St. Jude Medical, committee membership honoraria from Boston Scientific, Medtronic, St. Jude Medical and Zoll Medical, speaking honoraria from Zoll and fellowship support from Boston Scientific, Medtronic and St. Jude Medical.