Author + information
- Published online September 13, 2017.
- Nicolas Clementy, MD∗ (, )
- Arnaud Bisson, MD,
- Farid Challal, MD,
- Clementine Andre, MD,
- Bertrand Pierre, MD,
- Laurent Fauchier, MD, PhD and
- Dominique Babuty, MD, PhD
- ↵∗Cardiology Department, Trousseau Hospital, François Rabelais University of Tours, 60 rue du Plat d’Étain, 37044 Tours, France
Recent results from the Danish trial call into question the benefits of implantable cardioverter-defibrillator (ICD) in primary prevention for patients with nonischemic cardiomyopathy (NICM) and a reduced left ventricular ejection fraction (LVEF), considering that a majority of these well-treated patients also received cardiac resynchronization therapy (CRT) (1). We sought to evaluate the factors associated with appropriate therapies for ventricular arrhythmias over 220 beats/min in NICM patients included in the VH-RATE (Very High Rate study) study (2,3).
Consecutive NICM patients with a reduced LVEF despite optimal medical therapy, who underwent the implantation of an ICD in primary prevention of sudden cardiac death, were included. Devices were programmed with identical tachycardia settings: a monitoring zone starting at a rate of 170 beats/min or above, and a ventricular fibrillation zone at 220 beats/min or above, with nominal settings for the number of detection intervals, according to the manufacturer (average 18 ± 4 detection intervals). Shock therapies were programmed at maximum output and antitachycardia pacing (ATP) before or during charging, when available. A 24-h electrocardiographic Holter monitoring was performed in all patients just before implantation to detect the presence of nonsustained ventricular tachycardia (NSVT) episodes (≥3 consecutive complexes and <30 s). Time to first appropriate therapy (ATP or shock) was recorded. Follow-up ended with death, heart transplantation, or ICD removal.
A total of 223 patients were included (60 ± 11 years of age, LVEF 24 ± 7%, 26% single chamber, 22% dual chamber, and 52% CRT devices). Patients were well treated, with 97% having a beta-blocker, although information on renin-angiotensin-aldosterone system inhibitors was not available. During a mean follow-up of 4.7 ± 2.5 years (median 4.7 years [interquartile range: 3.2 years]) (i.e., 1,051 patient-years), 35 (16%) patients experienced at least 1 appropriate therapy, including 24 (11%) patients with shocks (11 for ventricular fibrillation [VF], 10 for fast monomorphic ventricular tachycardia [VT], and 3 for both VT and VF), and 11 (5%) patients with ATP-only therapies.
After adjustment for age; sex; LVEF; New York Heart Association functional class; single-chamber, dual-chamber, and biventricular devices; history of atrial fibrillation; NSVT at the time of implantation; complete atrioventricular block; and treatment with a beta-blocker and amiodarone, patients with NSVT (n = 67, 30%) was the only independent factor associated with a higher risk of appropriate therapy over 220 beats/min (adjusted hazard ratio: 4.81; 95% confidence interval: 2.33 to 10.30; p < 0.0001) (Figure 1). NSVT on 24-h Holter monitoring at the time of implantation was the only independent factor associated with a higher risk of appropriate shock on VF or polymorphic VT (adjusted hazard ratio: 5.21; 95% confidence interval: 1.63 to 18.80; p = 0.005). Patients with NSVT were also more likely to have NSVT episodes detected in the monitoring zone (170 to 220 beats/min) during follow-up (14.9% vs. 6.4%; p = 0.04).
Presence of NSVT alone indentifies a subgroup (30%) of NICM patients (37% implanted with a CRT device) at very-high risk of rapid and potentially life-threatening ventricular arrhythmia (5.0 events per 100 patient-years vs. 1.7 events per 100 patient-years; p < 0.0001) (4). Even if ICD treated fast ventricular arrhythmia is not an equivalent endpoint as all-cause mortality, our findings suggest that NSVT may predict a higher risk population of NICM patients who will actually benefit from implantation of a defibrillator in primary prevention of sudden cardiac death. A new randomized study in that population may be needed (5).
Please note: Dr. Clementy has received consulting honoraria and travel support from Boston Scientific, Medtronic, St. Jude Medical, and Sorin-LivaNova. Dr. Fauchier has served as a consultant for Medtronic. Dr. Babuty has received travel support and clinical study support from Biotronik, Boston Scientific, Medtronic, St. Jude Medical, and Sorin-LivaNova. All other authors have reported that they have no relationships relevant to the contents of this article to disclose.
- 2017 American College of Cardiology Foundation
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