S-ICD 'Noninferior' to Transvenous-Lead ICD in Head-to-Head PRAETORIAN Trial

May 08, 2020

The implantable defibrillator with subcutaneous leads, designed in part to minimize the risk for potentially serious lead-related complications, has reached a milestone by turning in a "noninferior" performance when it was compared with transvenous-lead devices in a first-of-its-kind head to head study.

Patients implanted with the subcutaneous-lead S-ICD (Boston Scientific) defibrillator showed a 4-year risk for inappropriate shocks or device-related complications similar to that seen with standard transvenous-lead implantable cardioverter defibrillators (ICD) in a randomized comparison.

At the same time, the S-ICD did its job by showing a highly significant three-fourths reduction in risk for lead-related complications, compared with ICDs with standard leads, in the trial with more than 800 patients, called PRAETORIAN.

The study population represented a mix of patients seen in "real-world" practice who have an ICD indication, of whom about two-thirds had ischemic cardiomyopathy, said Reinoud Knops, MD, PhD, Academic Medical Center, Hilversum, the Netherlands. About 80% received the devices for primary prevention.

Knops, the trial's principal investigator, presented the results online May 8 as one of the Heart Rhythm Society 2020 Scientific Sessions virtual presentations.

"I think the PRAETORIAN trial has really shown now, in a conventional ICD population — the real-world patients that we treat with ICD therapy, the single-chamber ICD cohort — that the S-ICD is a really good alternative option," he said to reporters during a media briefing.

"The main conclusion is that the S-ICD should be considered in all patients who need an ICD who do not have a pacing indication," Knops said.

This latter part is critical, because the S-ICD does not provide pacing therapy, including antitachycardia pacing (ATP) and cardiac resynchronization therapy (CRT), and the trial did not enter patients considered likely to benefit from it. For example, it excluded anyone with bradycardia or treatment-refractory monomorphic ventricular tachycardia (VT) and patients considered appropriate for CRT.

In fact, there are a lot reasons clinicians might prefer a transvenous-lead ICD over the S-ICD, observed Anne B. Curtis, MD, University at Buffalo, State University of New York, who is not associated with PRAETORIAN.

A transvenous-lead system might be preferred in older patients, those with heart failure, and those with a lot of comorbidities. "A lot of these patients already have cardiomyopathies, so they're more likely to develop atrial fibrillation or a need for CRT," conditions that might make a transvenous-lead system the better choice, Curtis told theheart.org | Medscape Cardiology.

"For a lot of patients, you're always thinking that you may have a need for that kind of therapy."

In contrast, younger patients who perhaps have survived cardiac arrest and probably don't have heart failure, and so may be less likely to benefit from pacing therapy, Curtis said, "are the kind of patient who you would probably lean very strongly toward for an S-ICD rather than a transvenous ICD."

Remaining patients, those who might be considered candidates for either kind of device, are actually "a fairly limited subset," she said.

The trial randomized 849 patients in Europe and the United States, from March 2011 to January 2017, who had a class I or IIa indication for an ICD but no bradycardia or need for CRT or ATP, to be implanted with an S-ICD or a transvenous-lead ICD.

The rates of the primary end point, a composite of device-related complications and inappropriate shocks at a median follow-up of 4 years, were comparable, at 15.1% in the S-ICD group and 15.7% for those with transvenous-lead ICDs.

Hazard Ratio (HR) for Outcomes at 4 Years, S-ICD vs Transvenous-Lead ICD, in PRAETORIAN
End Point S-ICD, n = 426, % Transvenous-lead ICD, n = 423, % HR (95% CI) P Value
Primary end point* 15.1 15.7 0.99 (0.71–1.39) .01 for noninferiority
Inappropriate shocks 9.7 7.3 1.43 (0.89–2.30) .14
Device-related complications 5.9 9.8 0.69 (0.44–1.09) .11
Lead-related complications 1.4 6.6 0.24 (0.10–0.54) .001
All-cause mortality 16.4 13.1 1.23 (0.89–1.70) .20
*Device-related complications or inappropriate shocks at 4 years

The incidence of device-related complications numerically favored the S-ICD group, and the incidence of inappropriate shocks numerically favored the transvenous-lead group, but neither difference reached significance.

Knops said the PRAETORIAN researchers are seeking addition funding to extend the follow-up to 8 years. "We will get more insight into the durability of the S-ICD when we follow these patients longer," he told theheart.org | Medscape Cardiology.

The investigator-initiated trial received support from Boston Scientific. Knops discloses receiving consultancy fees and research grants from Abbott, Boston Scientific, Medtronic, and Cairdac, and holding stock options from AtaCor Medical.

Heart Rhythm Society (HRS) 2020 Scientific Sessions: Abstract LBCT01-02. Available online May 8, 2020.

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