Efficacy of Medical Therapy for the Reduction of Heart Failure Events in Patients with Implanted Cardioverter Defibrillators

Abstract

Efficacy of Medical Therapy for the Reduction of HF Events. Background: Prophylactic therapy with the implantable cardioverter defibrillator (ICD) reduces the mortality among patients with left ventricular dysfunction; however, life-prolonging device therapy has been shown to be associated with an increased risk for subsequent heart failure (HF) events. There are limited data on the effect of the primary types of HF medications, angiotensin converting enzyme inhibitors (ACE-I), and beta-blockers on HF progression in ICD-treated patients. Methods: Multivariate Cox proportional hazards regression analysis was used to assess the effect of time-dependent medical therapy with ACE-I and beta-blockers on the development of HF in patients with an ICD in the Multicenter Automatic Defibrillator Trail (MADIT) II.Results: In multivariate analysis, ICD therapy was associated with a significant 39% increase in the risk of HF as compared with conventional medical therapy. ACE-I and beta-blockers exhibited a graded efficacy for the reduction in the risk of HF events in ICD-treated patients: the greatest risk reduction of HF was seen in patients taking combination therapy (HR = 0.36, P < 0.001), followed by patients using beta-blockers only (HR = 0.51, P = 0.017) and ACE-I only (HR = 0.64, P = 0.071). Beta-blocker subtypes (metoprolol [HR = 0.49, P = 0.001] and carvedilol [HR = 0.58, P = 0.004]) exhibited similar efficacy. Consistent results were demonstrated when the combined endpoint of HF or death was assessed.Conclusions: ICD-treated patients experience an increased risk for HF events that can be significantly attenuated by medical therapy with beta-blockers and ACE-

Optimal Medical Therapy Use Among Patients Receiving Implantable Cardioverter/Defibrillators

“…Despite differences in the magnitude of ␤-blocker underuse, which are unlikely to be explained by temporal trends, the fact is that in the current study, 5 an additional 18.7% of patients were not using an angiotensinconverting enzyme inhibitor or angiotensin receptor blocker. These observations lead to a fundamental question: why is the use of any of these drugs suboptimal when drug therapy is effective and available in generic formulation?…”

“…In the current report by Miller et al, 5 variables associated with lower use of OMT such as physician specialty are described; these findings are interesting but to some degree a distraction. There are only so many comparisons one can or should make in a descriptive analysis, and it is not clear if the authors tested for interactions among the covariates.…”

“…Although medical therapy optimization reduces mortality, 1 the risks of heart failure decompensation 5 and ventricular arrhythmias requiring shocks, 6 The in-hospital "snapshot" captured by the ICD Registry highlights a critical window of opportunity for therapy optimization for patients with low LVEF. Among patient and health care provider variables, surgical revascularization and ICD implantation by a boardcertified surgeon were 2 of the strongest factors independently associated with lower OMT use.…”

“…Recent studies have demonstrated that comorbidities such as renal failure, 1,2 underuse of ␤-blockers, 3 and inappropriate timing of implants 4 are all in play. In their analysis, Miller and colleagues 5 use data from the National Cardiovascular Data Registry (NCDR) to assess whether patients undergoing device implantation with reduced ejection fraction are receiving optimal medical therapy (OMT) for congestive heart failure. 5 This is a descriptive analysis for the period January 2007 to June 2009 that relies on NCDR reports by the participating institution of medication use at discharge.…”

“…In their analysis, Miller and colleagues 5 use data from the National Cardiovascular Data Registry (NCDR) to assess whether patients undergoing device implantation with reduced ejection fraction are receiving optimal medical therapy (OMT) for congestive heart failure. 5 This is a descriptive analysis for the period January 2007 to June 2009 that relies on NCDR reports by the participating institution of medication use at discharge. Given the limitations of the NCDR (for example, the lack of linkage to patient and pharmacy records), the investigators do not have information about antecedent and subsequent medication adherence or medication dosing.…”