Intravenous Atropine in Reducing Reperfusion Arrhythmias, Conduction Abnormalities, and Hypotension in Inferior ST-elevation Myocardial Infarction Undergoing Primary Percutaneous Coronary Intervention.

Objectives: Inferior ST-segment elevation myocardial infarction is frequently complicated by vagally mediated bradyarrhythmias and hypotension during reperfusion, contributing to increased morbidity. The Bezold-Jarisch reflex has been implicated in this hemodynamic instability; however, evidence supporting prophylactic atropine remains limited. The study evaluated whether intravenous atropine administered immediately before reperfusion reduces clinically meaningful bradyarrhythmias, hypotension, early sustained ventricular arrhythmias, and inpatient major adverse cardiovascular events in patients undergoing primary percutaneous coronary intervention. Methods: In this prospective single-center, randomized, double-blind, placebo-controlled trial, adults presenting within 12 h of symptom onset with inferior ST-segment elevation myocardial infarction were randomized 1:1 to intravenous atropine (1 mg) or placebo immediately before guidewire crossing or balloon inflation. Of 158 patients randomized, 150 patients were included in a prespecified modified intention-to-treat analysis, excluding 8 patients with angiographic no-reflow. The primary endpoint was a composite of hypotension and symptomatic bradycardia following reperfusion. Secondary endpoints included the individual components of the primary endpoint, sustained ventricular tachycardia or ventricular fibrillation, and inpatient major adverse cardiovascular events. Results: The primary endpoint occurred in 17.3% of atropine-treated patients and 49.3% of placebo-treated patients (relative risk 0.35, 95% CI 0.20-0.61), corresponding to an absolute risk reduction of 32.0% (95% CI 17.81-46.19) and a number needed to treat of 3 (p < 0.001). Atropine significantly reduced hypotension and symptomatic bradycardia. Sustained ventricular tachycardia or ventricular fibrillation occurred in 2.7% vs 13.3% of patients. No serious atropine-related adverse events were observed. Conclusions: Prophylactic atropine significantly reduces hypotension and bradyarrhythmias and may also reduce early ventricular arrhythmias and inpatient major adverse cardiovascular events in this population. Clinical trial registration: ClinicalTrials.gov identifier NCT07268586, retrospectively registered December 2025.