Key result
ICD therapy for fast ventricular arrhythmias was associated with increased mortality risk compared to no therapy (HR 2.27; 95% CI 1.48-3.48; P<0.001), whereas therapy for slow VA was not.
Why the study?
Patients with heart failure and an ICD for primary prevention have increased mortality after shock therapy, but the prognostic significance of shock versus antitachycardia pacing across different ventricular arrhythmia rates was unclear.
Does the rate of underlying ventricular arrhythmia treated by ICD therapy affect mortality risk in patients with mild heart failure?
RCT (n=1,790)
Yes
Does the rate of underlying ventricular arrhythmia treated by ICD therapy affect mortality risk in patients with mild heart failure?
Effect estimate: HR 2.27 (95% CI 1.48-3.48)
p-value: p=<0.001
In patients with mild heart failure and an ICD, increased mortality is associated with the rate of the underlying ventricular arrhythmia (fast VA) rather than the type of ICD therapy (shock vs. antitachycardia pacing) delivered.
Fast VA therapy signals higher mortality risk in mild HF independent of delivery mode; leaves open whether rate identifies substrate severity warranting targeted trials.
Background Patients with heart failure and an implantable cardioverter-defibrillator ( ICD ) for primary prevention are at increased mortality risk after receiving shock therapy. We sought to determine the prognostic significance of ICD therapies, both shock and antitachycardia pacing, delivered for different ventricular arrhythmia ( VA ) rates. Methods and Results We evaluated mortality risk among 1790 ICD -implanted patients from MADIT -CRT (Multicenter Automatic Defibrillator Implantation Trial With Cardiac Resynchronization Therapy). For the first analysis, patients were divided into mutually exclusive groups by the rate of treated VA only: slow VA (<200 beats per minute) and fast VA (≥200 beats per minute or ventricular fibrillation). In a secondary analysis, both the type of ICD therapy and VA rate were used. The reference group was always patients who had no ICD therapy. ICD therapy for fast VA was associated with increased mortality risk (hazard ratio [ HR] , 2.27; 95% CI , 1.48-3.48; P<0.001). However, mortality risk after ICD therapy for slow VA was similar to the risk related to no ICD therapy ( HR , 1.45; 95% CI , 0.86-2.44; P=0.162). Consistently, shocks ( HR , 2.96; 95% CI , 1.91-4.60; P<0.001) and antitachycardia pacing ( HR , 2.22; 95% CI , 0.96-5.14; P=0.063) for fast VA were both associated with increased mortality risk. Shocks and antitachycardia pacing for slow VA were not significantly associated with increased mortality risk ( HR , 1.43 [95% CI , 0.52-3.92; P=0.489]; and HR , 1.43 [95% CI, 0.80-2.56; P=0.232], respectively). Conclusions In patients with mild heart failure receiving ICD for primary prevention, mortality is associated with the rate of underlying VA rather than the type of therapy. These findings suggest that fast VA is a marker for increased mortality rather than shock therapy directly contributing to increased risk. Clinical Trial Registration URL : http://www.clinicaltrials.gov . Unique identifier: NCT 00180271.
No takes yet. Share an insight, caveat, or question.
Biton et al. (2019) conducted an RCT in Mild heart failure (n=1,790). ICD therapy for fast ventricular arrhythmias (≥200 beats per minute or ventricular fibrillation) vs. No ICD therapy was evaluated on Mortality (HR 2.27, 95% CI 1.48-3.48, p=<0.001). ICD therapy for fast ventricular arrhythmias was associated with increased mortality risk compared to no therapy (HR 2.27; 95% CI 1.48-3.48; P<0.001), whereas therapy for slow VA was not.
Synapse has enriched 5 closely related papers on similar clinical questions. Consider them for comparative context: