Assessment of Lactate Levels as Prognostic and Predictive Markers in Patients with Complete Atrioventricular Block-Uncorrected Proof

Objective: Complete atrioventricular (AV) block complicates management decisions, particularly regarding temporary pacemaker (TP) insertion. Lactate, an anaerobic byproduct, may reflect inadequate cardiac output and help guide this decision. We analyzed the prognostic value of lactate in patients with complete AV block.

Method: We retrospectively evaluated the medical records of adult patients presenting with complete AV block to our coronary care unit. Initial and subsequent venous blood lactate levels were analyzed for associations with adverse in-hospital outcomes, defined as renal injury, cardiac mortality, or the need for TP prior to permanent pacemaker implantation.

Results: The study included 140 patients (46.4% female; median age: 76 years, range: 32–96). Poor outcomes were observed in 22.9% of patients (n = 32), who exhibited significantly higher initial lactate levels (median: 3.1 vs. 2.0 mmol/L; P < 0.001). A lactate cutoff > 1.8 mmol/L predicted poor outcomes with 90.6% sensitivity and 43.5% specificity. Elevated baseline and follow-up lactate levels remained significant predictors, with 83.3% sensitivity and 85.5% specificity compared to normal baseline and follow-up lactate levels.

Conclusion: Increased lactate levels are independent determinants of poor in-hospital outcomes in patients with complete AV block. Lactate measurement may aid decision-making regarding TP even in hemodynamically stable patients. However, these results are hypothesis-generating, and prospective studies are needed to confirm clinical utility.

Keywords: Complete atrioventricular block, temporary pacemaker, venous blood lactate level