Primary endpoint
After a median duration of 49.0 (30.33-75.1) and 48.2(23.9-78.5) months’ follow-up in the CLBBB group and in the Non-CLBBB group, the incidence of the composite primary endpoint in the CLBBB group was significantly higher than the Non-CLBBB group (21.4% vs. 6.5%, HR 3.98, 95%CI 1.64-9.64, P = 0.002) (Figure 1). As a component of the composite primary endpoint, cardiovascular hospitalization was significantly higher in the CLBBB group (14.3% vs.3.6%, HR 4.83, 95%CI 1.55-15.07, P = 0.007). There were no significant differences in stroke and all-cause mortality between the two groups (Table 2). All the death cases in the two groups were due to cardiovascular causes.
In univariate regression analysis, QRS duration, heart failure, previous stroke, COPD, and CLBBB were significantly associated with the occurrence of the primary endpoint. After adjusting for these variations, CLBBB (HR 2.92, 95%CI 1.17-1.34 P = 0.022) was the only independent risk factor for the primary endpoint (Table 3).