Assessment of Primary Prevention Patients Receiving an ICD–Systematic Evaluation of ATP - APPRAISE ATP

Oct 11, 2024
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Author/Summarized by Author:
Amit Saha, MD
Summary Reviewer:
Anthony A. Bavry, MD,MPH,FACC
Trial Sponsor:
Boston Scientific Corporation
Date Published:
10/03/2024
Original Posted Date:
10/11/2024
References

Contribution To Literature:

The APPRAISE ATP trial showed that in a contemporary cohort of patients with a primary prevention ICD, ATP-first programming resulted in delayed time to first shock but did not reduce total shock burden over 5 years compared with a shock-only strategy.

Description:

The goal of the trial was to determine the efficacy of antitachycardia pacing (ATP) in terminating ventricular tachycardia (VT) compared with a shock-only strategy in patients with a primary prevention implantable cardioverter-defibrillator (ICD).

Study Design

  • Randomized
  • International multicenter

Patients with reduced left ventricular ejection fraction (LVEF) undergoing single- or dual-chamber transvenous ICD implantation for primary prevention were randomized in a 1:1 fashion to receive ATP plus shock (n = 1,302) or shock-only programming (n = 1,293). The ATP plus shock arm was programmed for only 1 ATP sequence of 8 beats followed by shocks if needed.

  • Total number of enrollees: 2,595
  • Follow-up: 5 years (mean 38 months)
  • Mean patient age: 64 years
  • Percentage female: 22%

Inclusion criteria:

  • Age ≥21 years
  • Primary prevention transvenous ICD implanted for: 1) prior myocardial infarction (MI) and LVEF ≤30%, or 2) LVEF ≤35% and New York Heart Association (NYHA) class II-III

Exclusion criteria:

  • Secondary prevention indication due to sustained VT ≥160 bpm lasting ≥30 seconds or ventricular fibrillation (VF)
  • NYHA class IV symptoms <3 months prior
  • Eligible for cardiac resynchronization therapy
  • MI or coronary revascularization <3 months prior

Other salient features/characteristics:

  • Single-chamber ICD implantation: 51%
  • Ischemic cardiomyopathy: 58%
  • Mean LVEF: 27%
  • Beta-blocker use: 91%

Principal Findings:

The primary outcome, first all-cause shock, for ATP plus shock vs. shock only at 5 years, was: 14.6% vs. 19.4%, hazard ratio [HR] 0.72 (95% confidence interval [CI] 0.57-0.92), p = 0.005 for superiority of ATP plus shock.

Secondary outcomes for ATP plus shock vs. shock only at 5 years:

  • First appropriate shock: HR 0.73 (95% CI 0.56-0.95)
  • First inappropriate shock: HR 0.65 (95% CI 0.44-0.97)
  • All-cause death: absolute incidence rate 15.1% vs. 13.5%, estimated HR 1.15 (95% CI 0.94-1.41)
  • First all-cause shock or death: HR 0.92 (95% CI 0.78-1.07)
  • Total shock burden: 12.3 vs. 14.9 shocks per 100 patient-years, HR 0.86 (95% CI 0.63-1.19), p = 0.70
  • VT/VF storm burden: 5.3 vs. 2.3 events per 100 patients, HR 2.26 (95% CI 1.18-4.30), p = 0.014

Electrical effects of ATP events:

  • Successful VT termination: 54.0%
  •  VT acceleration: 3.7%

Interpretation:

The current trial represents the first randomized data of ATP in a contemporary cohort of primary prevention ICD therapy. Successful termination of VT with ATP was much lower at 54% than previously reported in the 2004 PainFREE Rx II trial, which preceded the current practice of longer VT detection intervals and therefore treated nonsustained VT that would otherwise have spontaneously terminated without intervention. Although time to first appropriate or inappropriate shock was delayed in the ATP arm, total shock burden was not affected. This may partially reflect the albeit low risk of VT acceleration and consequent VT storm due to ATP as well as the severity of cardiomyopathy progression in this cohort with relatively high mortality at 5 years. Taken together, these data support the consideration of ATP capability, which is limited to transvenous and not subcutaneous ICDs, in the management of heart failure patients eligible for primary prevention device implantation.

References:

Schuger C, Joung B, Ando K, et al. Assessment of Antitachycardia Pacing in Primary Prevention Patients: The APPRAISE ATP Randomized Clinical Trial. JAMA 2024;Oct 3:[Epub ahead of print].

Editorial Comment: Sandhu A, Matlock D, Varosy PD, et al. Shock First or Pace First to Break Ventricular Tachycardia? A New Layer of Complexity in ICD Shared Decision-Making. JAMA 2024;Oct 3:[Epub ahead of print].

Clinical Topics: Arrhythmias and Clinical EP, Prevention, Implantable Devices, SCD/Ventricular Arrhythmias

Keywords: Defibrillators, Implantable, Primary Prevention, Shock, Tachycardia, Ventricular


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