Study objectives: Even in high-risk population groups, not all patients have the same risk of sudden cardiac death (SCD). Given the emerging data about the amino-terminal fragment of the brain natriuretic peptide prohormone (NT-proBNP) value in heart failure, we planned to evaluate the importance of NT-proBNP levels in predicting the occurrence of malignant arrhythmias in patients with ischemic cardiomyopathy and implantable cardioverter-defibrillators (ICDs).
Design: Prospective study.
Setting: Tertiary referral center.
Patients: Thirty five ambulatory patients with previous myocardial infarction, left ventricular ejection fraction < 35%, and ICDs for primary prevention of SCD according to Multicenter Automatic Defibrillator Implantation Trial I criteria.
Interventions: Venous blood samples for plasma NT-proBNP measurement were obtained after 30 min of supine rest from all patients at the beginning of the study. Patients were evaluated every 2 months, or sooner in cases of device discharges, during a 1-year follow-up period. Data concerning arrhythmias and device therapy were stored at the time of device interrogation on each follow-up visit.
Measurements and results: During 1-year follow-up, 11 of 35 patients (31.4%) received 18 antiarrhythmic device therapies for ventricular tachyarrhythmia (VT). Patients who experienced such arrhythmias had NT-proBNP levels of 997.27 ± 335.14 pmol/L (mean ± SD), whereas those without VT had NT-proBNP levels of 654.87 ± 237.87 pmol/L (p = 0.001). An NT-proBNP cutoff value of 880 pmol/L had a sensitivity of 73%, a specificity of 88%, a positive predictive value of 80%, and a negative predictive value of 88% for the prediction of occurrence-sustained VT events.
Conclusion: To achieve the maximum benefit by ICD therapy, more precise risk stratification is required, even in high-risk, post-myocardial infarction patients. Plasma NT-proBNP levels comprise a promising method that could help in the better identification of a patient group with an even higher risk of sudden death.