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Randomized Pragmatic Trial of Pacemaker Versus Implantable Cardiac Monitor in Syncope and Bifascicular Block
Robert Sheldon1, Mario Talajic2, Anthony Tang3
1Libin Cardiovascular Institute of Alberta, University of Calgary, Calgary, Alberta, Canada.
Insights
Empiric permanent pacing reduced major adverse events in older patients with bifascicular block and syncope. However, pacing did not reduce syncope recurrence, suggesting other causes like vasodepressor syncope.
Area of Science:
- Cardiology
- Electrophysiology
- Clinical Trials
Background:
- Syncope in patients with bifascicular heart block can stem from intermittent complete heart block, but other diagnoses are possible.
- The optimal management strategy, either empiric permanent pacing or awaiting results from an implantable cardiac monitor (ICM), remains unclear.
Purpose of the Study:
- To determine if empiric permanent pacing is more effective than using an implantable cardiac monitor (ICM) in reducing major composite events in patients with bifascicular block and recent syncope.
- To compare the incidence of cardiovascular death, syncope, bradycardia requiring pacemaker insertion, and device complications between the two strategies.
Main Methods:
- A multinational, randomized, pragmatic clinical trial (SPRITELY study) involving patients aged 50 years or older with bifascicular block, preserved left ventricular function, and at least one syncope episode in the prior year.
- Participants were randomized to either empiric permanent pacemaker implantation or monitoring with an ICM.
- The primary outcome was a composite of cardiovascular death, syncope, bradycardia leading to pacemaker insertion, and device complications.
Main Results:
- Fewer composite primary outcomes occurred in the empiric pacing group (35%) compared to the ICM group (76%) (P < 0.0001).
- Actuarial probabilities of a primary outcome were significantly lower with empiric pacing (0.45 vs. 1.00; P < 0.001).
- The incidence of syncope was similar between the pacing and ICM groups (29% vs. 26%; P = 0.95).
Conclusions:
- Empiric permanent pacing significantly reduced major adverse events in older patients with bifascicular block and recent syncope compared to ICM.
- Permanent pacing did not decrease the likelihood of recurrent syncope, indicating that vasodepressor syncope may be a significant contributing factor in this population.
Objectives:
In this study, the authors tested whether a strategy of empiric permanent pacing reduces major composite events more effectively than acting on the results of an implantable cardiac monitor (ICM).
Background:
Syncope may be caused by intermittent complete heart block in patients with bifascicular heart block, but competing diagnoses coexist. Whether empiric permanent pacing or acting on investigative results provides best care is unknown.
Methods:
This was a multinational, randomized, pragmatic clinical trial of patients ≥50 years of age with bifascicular block, preserved left ventricular function, and ≥1 syncope in the preceding year. The primary composite outcome measure comprised cardiovascular death, syncope, bradycardia resulting in pacemaker insertion, and device complications.
Results:
There were 57 and 58 subjects randomized to receive a pacemaker or ICM. A total of 41 patients had left bundle branch block and 74 had right bundle branch block and a left fascicular block. Patients were followed for a median 33 months. There were fewer composite primary outcomes in patients randomized to pacemaker compared with ICM, respectively (20 [35%] vs 44 [76%]; chi square P < 0.0001), with lower actuarial probabilities of a primary outcome (0.45 and 1.00; P < 0.001). Syncope was as likely in the groups randomized to receive a pacemaker or ICM (29% vs 26%, chi-square P = 0.95).
Conclusions:
Empiric permanent pacing compared with ICM reduced major adverse events but not syncope in older patients with bifascicular block and recent syncope. There remains a substantial likelihood of syncope recurrence in patients who receive a permanent pacemaker likely caused by vasodepressor syncope. (Syncope: Pacing or Recording in the Later Years [SPRITELY]; NCT01423994).
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