Periodic repolarization dynamics may identify ICD candidates
PARIS — Use of periodic repolarization dynamics, a marker for repolarization instability associated with sympathetic activity, appeared to identify patients whose mortality risk would be reduced with an implantable cardioverter defibrillator, according to new data from the EU-CERT-ICD study.
In a prespecified substudy from the prospective, nonrandomized EU-CERT-ICD study, the researchers evaluated the interaction between periodic repolarization dynamics and the treatment effect of ICDs on mortality. The results were presented at the European Society of Cardiology Congress and published simultaneously in The Lancet.
“Evidence regarding effectiveness of prophylactic ICD implantation comes from randomized trials that our outdated in terms of heart failure management, pharmacological treatments and ICD programming. Sudden death rates substantially declined over the years. Only few patients undergoing prophylactic ICD implantation today ever develop life-threatening arrhythmias and appropriate ICD interventions. ICD therapy has important side effects that potentially affect all patients,” Axel Bauer, MD, from Medizinische Klinik und Poliklinik I, Munich University Clinic, Munich, told Cardiology Today. “We therefore designed EU-CERT-ICD to re-evaluate the effectiveness of prophylactic ICD therapy and to identify patients who really benefit from prophylactic ICD therapy in terms of mortality reduction.”
In the main study, 1,371 patients with ischemic or nonischemic cardiomyopathy and ejection fraction 35% or less were implanted with an ICD (n = 968) or managed conservatively (n = 403). The primary outcome was all-cause mortality. Follow-up was a median of 2.7 years in the ICD group and 1.2 years in the control group.
Compared with the control group, the ICD group had a 43% reduction in mortality (HR = 0.57; 95% CI, 0.41-0.79), according to Bauer and colleagues.
Bauer and colleagues found periodic repolarization dynamics successfully predicted the ICD treatment effect on mortality (P = .0307).
Patients with periodic repolarization dynamics of at least 7.5 deg had greater mortality benefits from the ICD than patients with periodic repolarization dynamics of less than 7.5 deg (adjusted HR for ICD group vs. control group in 7.5 deg = 0.25; 95% CI, 0.13-0.47; aHR for ICD group vs. control group in < 7.5 deg = 0.69; 95% CI, 0.47-1; P for interaction = .0056), according to the researchers.
In patients with periodic repolarization dynamics of at least 7.5 deg, the number needed to treat with an ICD to prevent one death was 3.1, compared with 18.3 for patients with periodic repolarization dynamics less than 7.5 deg, Bauer and colleagues determined.
“Many patients who receive ICDs today do not really benefit from ICD implantation. [Periodic repolarization dynamics]-based stratification significantly affects the number needed to treat to save a life. We are convinced that [periodic repolarization dynamics] has the potential to guide prophylactic ICD implantation. The algorithms could be easily implemented in existing ECG devices,” Bauer told Healio.
In a related editorial published in The Lancet, Sana M. Al-Khatib, MD, professor of medicine at Duke University Medical Center and member of the Duke Clinical Research Institute, wrote that the findings need to be validated in other cohorts and best practices for measuring periodic repolarization dynamics need to be established.
“Periodic repolarization dynamics are not yet ready for prime time,” she wrote. “Studies combining periodic repolarization dynamics with other risk-stratification parameters are needed. Large prospective studies linking periodic repolarization dynamics with ICD shocks and causes of death would be important. Until such results are available, periodic repolarization dynamics are unlikely to gain traction as a test that can be consistently used to select patients for primary prevention of sudden cardiac death with ICDs.” – by Erik Swain
Bauer A, et al. Late-Breaking Science in Arrhythmias. Presented at: European Society of Cardiology Congress; Aug. 31-Sept. 4, 2019; Paris.
Disclosures: Bauer and Al-Khatib report no relevant financial disclosures. Please see the study for the other authors’ relevant financial disclosures.