Aldosterone Receptor Antagonists Do Not Reduce Defibrillator Shocks: Presented at HFSA

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Title: Aldosterone Receptor Antagonists Do Not Reduce Defibrillator Shocks: Presented at HFSA
URL: http://www.pslgroup.com/dg/22D702.htm
Doctor's Guide
September 24, 2008

By Jill Stein

TORONTO -- September 24, 2008 -- Aldosterone receptor antagonists (ARAs) do not decrease the frequency of shocks from implantable cardioverter defibrillators (ICDs), according to data released at the 12th Annual Scientific Meeting of the Heart Failure Society of America (HFSA).

Jason N. Hoeksema, PharmD, University of Illinois Medical Center at Chicago, Deerfield, Illinois, and colleagues compared the incidence of ICD shocks, antitachycardia pacing (ATP), and nonsustained ventricular tachycardia (NSVT) in patients with ICDs who were receiving an ARA or not receiving an ARA.

"Therapy that can reduce ICD shocks may improve the quality of life for patients with ICDs," said Dr. Hoeksema, speaking at a poster session here on September 22. "Aldosterone activity is implicated in cardiac remodelling, which provides a substrate for the development of arrhythmias that necessitate ICD shocks."

ARAs attenuate cardiac remodelling, and large, randomised, controlled trials have shown that ARAs significantly reduce the risk of sudden cardiac death, the researchers noted; however, whether ARAs reduce ICD shock frequency was not known.

For the trial, the researchers reviewed the medical records of 94 adult patients who had had an ICD for at least 1 year and were either being treated with an ARA for at least 1 year (n = 44) or were not receiving an ARA but had no contraindications for an ARA (n = 50).

The study found that the incidence of ICD shocks, ATP, and NSVT were similar between patients taking an ARA and patients not taking an ARA.

Overall, ARA-treated patients had an event rate of 0.89 +- 2.16 per patient-year for ICD shocks versus 0.30 +- 0.89 in the non-ARA group (P = .10). The event rates per patient-year for ATP were 0.45 +- 2.0 and 0.98 +- 3.7 for ATP for the 2 groups, respectively (P = .39). For NVST, the rates were 2.9 +- 5.5 and 3.16 +- 5.5 for the 2 groups, respectively (P = .83).

Dr. Hoeksema said that although the findings do not support a reduction in the incidence of ICD shocks, ATP, or NSVT with ARA therapy, the results should be interpreted cautiously given potential study limitations. For example, the analysis was retrospective and conducted at a single centre, and there was no patient randomisation. Also, patients in the ARA group likely had more severe cardiac disease, as evidenced by the higher prevalence of cardiomyopathy in this group.

[Presentation title: Effect of Aldosterone Antagonists on Shock Frequency With Implantable Cardioverter Defibrillators. Abstract 240]

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