Author + information
- Carlo Bonanno, MD∗ (, )
- Antonio Rossillo, MD,
- Mariemma Paccanaro, MD,
- Angelo Bruno Ramondo, MD and
- Antonio Raviele, MD
- ↵∗Department of Cardiology, San Bortolo Hospital, Viale Rodolfi, 37, 36100 Vicenza, Italy
Testing of the implantable cardioverter-defibrillator (ICD) for its ability to correctly sense, detect, and terminate ventricular fibrillation has been an important part of device implantation since procedures in humans began in the early 1980s. However, in recent years, there is some controversy as to whether defibrillation testing (DFT) should be performed. Addressing to this issue, 3 randomized controlled trials have been published, including the substudy of the RAFT-DFT (Resynchronization for Ambulatory Heart Failure) trial (1), the NORDIC-ICD (NO Regular Defibrillation testing In Cardioverter Defibrillator Implantation) trial (2), and the SIMPLE (Shockless IMPLant Evaluation) trial (3). In this study, we undertook a meta-analysis in order to summarize the efficacy and safety of DFT, in comparison with no-DFT at the time of ICD implantation.
We searched Medline for randomized controlled trials of DFT testing in ICDs that had been published through October 2015. Data on mortality, efficacy, and safety were analyzed and pooled separately. Relative risk (RR) with 95% confidence interval (CI) for the respective outcomes in each study was calculated. We used fixed or random-effects models based on the Mantel-Haenszel method to combine the RR from the trials included, when appropriate. A test of heterogeneity was conducted and the Q statistic was calculated. The I2 index was used to summarize the proportion of the total variability in the estimates. A 2-tailed p ≤ 0.05 was considered statistically significant. Data were analyzed by means of Review Manager 5.3 (The Nordic Cochrane Centre, The Cochrane Collaboration, Copenhagen, Denmark).
Three studies with 3,722 participants randomly assigned to DFT (n = 1,868) or no DFT (n = 1,854) were included in this meta-analysis (1–3).
DFT had no effect on the total mortality rate (RR: 1.00; 95% CI: 0.86 to 1.17; I2 = 0%; p = 0.99) (Figure 1). Arrhythmic death occurred in 144 patients and was similar between groups (RR: 1.60; 95% CI: 0.46-5.59; I2 = 45%; p = 0.46).
A lower appropriate shock efficacy rate was observed in the group with DFT than in the group without DFT, with a trend toward a significant difference (RR: 0.98; 95% CI: 0.95 to 1.00; I2 = 0%; p = 0.08). When we considered the first appropriate ICD shock, the pooled effect estimate indicated that patients with DFT had a statistically significant lower efficacy rate than did the group without DFT (RR: 0.93; 95% CI: 0.89 to 0.98; I2 = 0%; p = 0.004).
A total of 322 patients had serious adverse events within 30 days after ICD implantation, 178 of whom had undergone DFT and 144 had not (RR: 1.23; 95% CI: 1.00 to 1.52; I2 = 0%; p = 0.05) (Figure 2). Intraoperative hypotension was the only adverse event somewhat higher in patients with DFT, but it was not significantly different between the DFT and the no-DFT groups (RR: 3.83; 95% CI: 0.69 to 21.31; I2 = 47%; p = 0.13).
The findings from our systematic review and meta-analysis suggest that DFT at the time of ICD implantation has no impact on mortality during follow-up. Furthermore, the effect estimate reveals a 2% to 11% statistically significant higher first appropriate shock efficacy in the group without DFT versus those with DFT. The higher first-shock efficacy in the group without DFT did not translate into a difference in any appropriate shock efficacy in interrupting ventricular arrhythmias in either group.
The RAFT-DFT, SIMPLE, and NORDIC-ICD trials demonstrated similar modest increases in overall procedural complications in patients who underwent DFT, which did not quite reach statistical significance in any individual trial. When we pooled the data, DFT was associated with a statistically significant 23% elevated risk of total procedural complications. However, specific complications that occurred more frequently in patients with DFT were typically short lived, such as intraoperative hypotension.
Our results are consistent with previous meta-analysis (4) and provide further support to the recent recommendation to omit DFT in patients undergoing initial transvenous ICD implantation procedures (5).
Please note: The authors have reported that they have no relationships relevant to the contents of this paper to disclose.
- 2017 American College of Cardiology Foundation
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