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07 Dec 2018
Less focus must be given on pretreatment blood pressure (BP) levels, which rarely predict future untreated BP levels or rule out capacity to benefit from BP lowering in high cardiovascular risk patients, according to recent study. Focus must be directed instead on prompt, empirical treatment to maintain lower BP for individuals with high BP or high risk.

Life vest fails to confer significant survival benefit in myocardial infarction

Jairia Dela Cruz
28 Nov 2018

A wearable cardioverter–defibrillator does not appear to significantly reduce the risk of arrhythmic death in patients with a recent myocardial infarction (MI) and an ejection fraction of 35 percent as compared with medical therapy, according to the results of the VEST trial.

VEST randomized 2,302 patients to receive a guideline-directed therapy either alone (control group; n=778; mean age 60.9 years; 72.8 percent male) or in addition to a wearable cardioverter–defibrillator (device group; n=1,524; mean age 61.4 years; 74.7 percent male). Those in the device group wore the device for a median of 18.0 hours per day.

The primary outcome of arrhythmic death, defined as the composite of sudden death or death from ventricular tachyarrhythmia, at 90 days did not significantly differ between the device and control groups (1.6 percent vs 2.4 percent; relative risk [RR], 0.67; 95 percent CI, 0.37–1.21; p=0.18). [N Engl J Med 2018; 379:1205-1215]

Moreover, no significant between-group difference materialized in terms of the two secondary outcomes. Specifically, death from any cause occurred in 3.1 percent of patients in the device group and in 4.9 percent of those in the control group (RR, 0.64; 0.43–0.98; uncorrected, p=0.04), whereas nonarrhythmic death was documented in 1.4 percent and 2.2 percent, respectively (relative risk, 0.63; 0.33–1.19; uncorrected, p=0.15).

“With most approaches to correction for multiple testing, the P value for the analysis of total mortality was not significant,” the investigators said.

Of the 48 patients in the device group who died, a quarter (n=12) were wearing the device at the time of death. A total of 20 participants in the device group (1.3 percent) received an appropriate shock, and nine (0.6 percent) received an inappropriate shock. Itch and rash occurred more frequently in the device vs control group (p<0.001), while shortness of breath was more common in the control group (p=0.004).

“The trial may have been underpowered to detect a beneficial effect of the wearable cardioverter–defibrillator on the primary outcome. Our power calculation anticipated a 58-percent lower rate of arrhythmic death with the device than without it. The power was, in part, reduced because 5 percent of the deaths were adjudicated as being of indeterminate cause and were thus removed from the primary analysis,” the investigators explained.

In an accompanying editorial, Drs Michael Field from the Medical University of South Carolina and Richard Page from the University of Wisconsin School of Medicine and Public Health noted that the results of VEST might have favoured the device with prolonged wear time. [N Engl J Med 2018;379:1274-1275]

“In an as-treated analysis, there were significantly fewer deaths when patients were wearing the device than when they were not. The majority of deaths in the device group occurred in patients who were not wearing the device,” they pointed out.

Additionally, VEST highlights the challenges of reducing mortality in the context of ventricular tachyarrhythmias, which have been reported to present a poor outcome even when swiftly treated, according to Field and Page.

“We would advocate for a thorough discussion with the patient that both acknowledges the limitations of the available evidence and provides an understanding of the potential harms, such as frequent device alarms and potential for inappropriate shocks. In the context of a particularly motivated patient who is at high risk, we would still offer the wearable cardioverter–defibrillator,” they said.

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Most Read Articles
07 Dec 2018
Less focus must be given on pretreatment blood pressure (BP) levels, which rarely predict future untreated BP levels or rule out capacity to benefit from BP lowering in high cardiovascular risk patients, according to recent study. Focus must be directed instead on prompt, empirical treatment to maintain lower BP for individuals with high BP or high risk.