Rapid Rate Non-Sustained Ventricular Tachycardia Found on ICD Interrogation: Relationship of NSVT to Outcomes in the SCD-HeFT Trial
Is nonsustained ventricular tachycardia with a rapid rate (RR-NSVT) detected by interrogation of implantable cardioverter-defibrillators (ICDs) of prognostic significance in patients with heart failure?
This was a post-hoc analysis of ICD stored electrograms in the 811 patients (mean age 60 years, mean ejection fraction 23%) who received an ICD in the SCD-HeFT (Sudden Cardiac Death in Heart Failure Trial) study. The criteria for RR-NSVT were a duration ≥18 beats and a rate ≥188 bpm. The relationships between RR-NSVT and major outcomes were analyzed.
RR-NSVT (mean duration 26 beats, mean rate 232 bpm) was documented by ICD interrogation in 186/811 patients (23%). RR-NSVT was strongly associated with the risk of a subsequent appropriate ICD shock (hazard ratio, 4.2). By multivariate analysis, RR-NSVT was independently associated with a 2.4-fold higher risk of death compared to patients without RR-NSVT, and a three-fold higher risk of death or an appropriate ICD shock.
The authors concluded that RR-NSVT is associated with a higher risk of death and appropriate ICD shocks in patients with heart failure.
Prior studies on the clinical significance of NSVT have presented conflicting results, with several studies concluding that NSVT does not have prognostic value. However, NSVT in the prior studies was defined as ≥3 beats in duration at a rate >100-120 bpm. The present study provides strong evidence that NSVT does have prognostic significance when the runs are long and has a rate ≥188 bpm. The results suggest that RR-NSVT should prompt more aggressive medical therapy with agents such as beta-blockers or amiodarone, although it is not clear that this will attenuate the higher risk of death.
Clinical Topics: Arrhythmias and Clinical EP, Heart Failure and Cardiomyopathies, Implantable Devices, SCD/Ventricular Arrhythmias, Atrial Fibrillation/Supraventricular Arrhythmias, Acute Heart Failure
Keywords: Heart Diseases, Incidence, Prognosis, Defibrillators, Death, Heart Failure, Disease Management, Tachycardia
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