Prediction of Cardiac Death in Patients with Bundle Branch Block After Myocardial Infarction

Background Left (LBBB) and right (RBBB) bundle branch block (BBB) patients have an increased incidence of cardiac death after myocardial infarction (Ml). The purpose of this study was to assess the value of the signal‐averaged electrocardiogram (SAECG) and other clinical variables for the prediction of cardiac death after MI in BBB patients. Methods SAECGs were recorded 5–15 days after MI in 76 LBBB and 79 RBBB patients. The SAECG was analyzed in the time domain and the frequency domain (wavelet analysis in 7 frequency bands ranging from 0.05 to 250 Hz). Results During follow‐up (17 ± 8 months), cardiac death occurred in 22 LBBB (28.9%) and 12 RBBB patients (15.2%). None of the SAECG time‐domain variables were significantly different between patients with and without cardiac death. In LBBB patients, univariate analysis showed that one wavelet parameter in the 3.9‐ to 7.8‐ Hz frequency band (P = 0.008), inhospital recurrent Ml (P = 0.002), left ventricular ejection fraction (LVEF) < 30% (P = 0.004), lack of percutaneous transluminal coronary angioplasty (P = 0.02), and history of angina (P = 0.029) were significantly different in cardiac death patients. In RBBB patients, only recurrent angina was significantly different (P = 0.025). In LBBB patients, the combination of recurrent Ml or LVEF < 30% displayed the best predictive values: sensitivity (85.7%), specificity (76.6%), positive (52.2%), negative (94.7%), and total (78.7%) predictive accuracies and risk ratio of 9.9. The effect of recurrent Ml and LVEF < 30% remained after statistical adjustment by means of regression using Cox proportional hazards. Conclusions High‐risk Ml patients can be identified by recurrent Ml and LVEF < 30% in LBBB patients, and by recurrent angina in RBBB patients. SAECG did not demonstrate incremental information for the purpose of risk stratification in BBB patients.