Long-term prognostic value of heart rate recovery in patients with left bundle branch block without inducible ischemia and without known coronary artery disease

Abstract Background Heart rate recovery (HRR) has been shown to predict cardiovascular and all-­cause morbidity and mortality. Left bundle branch block (LBBB) is often associated with significant heart disease and is often the result of underlying coronary artery disease (CAD), myocardial injury, strain or hypertrophy. However, there are insufficient data on the prognostic value of HRR in patients with LBBB without inducible ischemia and without known CAD. Aim The aim of this study was to determine the long-term prognostic value of HRR in patients with LBBB without inducible ischemia and without known CAD. Methods This retrospective study included 182 patients (64, 35.2% male gender, average age 63 ± 10 years) with LBBB and without known CAD who were referred to the SECHO test for chest pain. All the patients had negative SECHO test according the Bruce protocol. Risk factors for CAD (diabetes, smoking, hypertension, high cholesterol and positive family history of CAD), functional capacity (Metabolic Equivalents - METs) and heart rate recovery (HRR) were recorded in all patients. HRR was calculated as the difference between heart rate at the peak stress and heart rate in the first minute of rest. Slow HRR was defined as ≤18 beats/min. Median follow up of the patients was 102.5 months (IQR 68-146 months) for the occurrence of MACE (all-cause mortality, non-fatal myocardial infarction (MI), coronary artery bypass grafting (CABG) and percutaneous coronary intervention (PCI)). Results Overall, 16pts (8.8%) had slow HRR. During the follow-up period 34 out of 182 patients (18.7%) had an adverse event (16 deaths, 10 non-fatal MI, 1 CABG and 7 PCI). Using the Cox regression analysis, univariate predictors of MACE were age (B=0.050, HR 1.051 [95% CI 1.011-1.093], p=0.012), hypertension (B=-1.219, HR 3.385 [95% CI 1.071-10.699], p=0.038), MET (B=-0.183, HR 0.833 [95% CI 0.706-0.982], p=0.030), diabetes (B=0.981, HR 2.667 [95% CI 1.267-5.612], p=0.010) and slow HRR (B=1.171, HR 3.225 [95% CI 1.307-7.959], p=0.011). However, in the multivariate analysis only slow HRR remained the independent predictor of MACE (B=0.974, HR 2.648 [95% CI 0.980-7.151], p=0.048). Using the Kaplan-Meier survival curve we see that the patients with slow HRR had much shorter event-free time compared to the patients with normal HRR (106.9 ± 14.9 months vs 157.9 ± 24 months, Log Rank 7.227, p=0.007) (Figure 1.). Conclusion Slow HRR is an independent long-term predictor of adverse events in patients with left bundle branch block without inducible ischemia and without known coronary artery disease.Kaplan-Meier survival curve for the MACE