Early low-molecular-weight heparin versus early aspirin after off-pump coronary artery bypass: a retrospective propensity score-matched exploratory study

Abstract

The optimal early antithrombotic strategy after off‑pump coronary artery bypass grafting (OPCAB) remains controversial. This single‑center retrospective propensity‑score matched study compared antithrombotic therapies initiated at postoperative 6 h. Clinical data were retrieved from institutional electronic medical records. OPCAB patients were grouped into aspirin or early LMWH cohorts. Propensity‑score matching (PSM) balanced baseline confounders. Primary efficacy endpoint was 12‑month major adverse cardiac and cerebrovascular events (MACCE); primary safety endpoint was in‑hospital major bleeding. Graft failure served as a secondary imaging endpoint. In the unmatched cohort, MACCE occurred in 8.07% of aspirin patients versus 3.61% of LMWH patients (OR 0.43, 95%CI 0.21‑0.87); major bleeding rates were 3.73% and 2.46% (OR 0.65, 95%CI 0.25‑1.71). After PSM, MACCE rates were 8.61% (aspirin) and 2.65% (LMWH; conditional logistic regression OR 0.31, 95%CI 0.10‑0.94, P = 0.039). Matched stroke rates were 5.96% versus 1.32% (OR 0.21, 95%CI 0.05‑1.00). Major bleeding rates were 3.31% and 4.64% (OR 1.42, 95%CI 0.44‑4.58). All‑cause and cardiogenic mortality were similar between groups. Among selected OPCAB patients without high bleeding risk or postoperative coagulopathy, early LMWH was not associated with a difference in major bleeding compared with aspirin. Numerically lower MACCE, largely driven by fewer ischaemic strokes, was seen in the LMWH group. Since PSM only balanced preoperative variables and critical postoperative‑6‑hour treatment‑selection data were unavailable, these findings represent observational associations rather than causal evidence for LMWH benefit. Given retrospective limitations, residual confounding and few clinical events, these exploratory results require cautious interpretation and warrant validation by large prospective studies with complete early‑postoperative physiological data.