Left bundle branch block in type 2 diabetes mellitus: a sign of advanced cardiovascular involvement

To evaluate left bundle branch block (LBBB) as an indicator of advanced cardiovascular involvement in diabetic (DM) patients by examining left ventricular systolic function and proteinurea.

Data of 26 diabetic patients with left bundle branch block (DM with LBBB) were compared with data of 31 diabetic patients without left bundle branch block (DM without LBBB) and 18 nondiabetic patients with left bundle branch block (non-DM with LBBB). The inclusion criteria were age >45 years, and diabetes mellitus type 2 of >5 years.

Mean ages of patients in DM with LBBB, DM without LBBB, and non-DM with LBBB groups were 67 +/- 8, 68 +/- 10, and 65 +/- 10 years, respectively (P = NS). Females were 65%, 61%, and 61%, respectively (P = NS). Left ventricular ejection fraction in DM with LBBB was significantly lower than in DM without LBBB and non-DM with LBBB (30 +/- 10% vs 49 +/- 12% and 47 +/- 8%, P < 0.01). Left ventricular end-diastolic volume was significantly higher in DM with LBBB than in DM without LBBB and non-DM with LBBB (188.6 +/- 16.4 mL vs 147.5 +/- 22.3 mL and 165.3 +/- 15.2 mL, P < 0.03). Similarly, left ventricular end-systolic volume was significantly higher in DM with LBBB than in DM without LBBB and non-DM with LBBB (135.4 +/- 14.7 mL vs 83.7 +/- 9.5 mL and 96.6 +/- 18.4 mL, P < 0.02). No statistically significant difference was seen in left atrial size. Proteinurea in DM with LBBB (79.4 +/- 18.9 mg/dL) was significantly higher than in DM without LBBB (35.6 +/- 8.5 mg/dL, P < 0.05) and non-DM with LBBB (12 +/- 3.5 mg/dL, P < 0.05); however, there was no significant difference in Hb A1c levels in DM with LBBB and DM without LBBB (9.01% vs 7.81%, P = NS).

Left bundle branch block in diabetic patients indicates advanced cardiovascular involvement manifesting with more severe left ventricular systolic dysfunction and proteinurea compared to both diabetic patients without left bundle branch block and nondiabetic patients with left bundle branch block.