Adenosine Pre-Medication in Primary Percutaneous Coronary Intervention

Primary objective of the study is to evaluate the impact of adenosine pre-medication on incidence of slow flow/no-reflow after primary percutaneous coronary intervention.

Background: Primary percutaneous coronary intervention (PCI) is the preferred reperfusion strategy for ST-segment elevation myocardial infarction (STEMI); however, optimal myocardial perfusion is not achieved in all patients due to the slow flow/no-reflow phenomenon. This condition, defined as inadequate myocardial perfusion despite patent epicardial arteries, is associated with worse clinical outcomes. Adenosine, owing to its vasodilatory, anti-inflammatory, and antiplatelet properties, may improve microvascular perfusion. While its use during PCI is established, its prophylactic role prior to PCI remains unclear. Study Design: This is a multicenter, single-blinded, randomized controlled trial conducted at NICVD Karachi and its satellite centers (Liyari and Larkana) over 12 months. A total of 1,148 STEMI patients undergoing primary PCI will be randomized in a 1:1 ratio using block randomization. Intervention: Intervention Group: Intracoronary adenosine pre-medication (2 mg for left coronary artery, 1 mg for right coronary artery, diluted in 20 mL normal saline) plus standard care. Control Group: Standard pharmacological management alone. Participants: Adults (≥18 years) with STEMI undergoing primary PCI. Key exclusions include cardiogenic shock, heart block, adenosine allergy, and refusal to consent. Outcomes: Primary Outcome: Incidence of slow flow/no-reflow (TIMI flow grade 0-II). Secondary Outcome: Myocardial Blush Grade (0-III). Safety: Potential adverse effects such as transient bradycardia or heart block will be managed per institutional protocols. Data and Analysis: Baseline, procedural, and outcome data will be collected. Statistical analysis will be performed using SPSS, with appropriate tests applied for continuous and categorical variables. A p-value ≤0.05 will be considered significant.

Inclusion Criteria: * All patients with acute STEMI undergoing primary PCI * Patients of either sex, ≥18 years of age. Exclusion Criteria: * STEMI patients with cardiogenic shock at presentation * Patients with heart block * Allergy to adenosine * Patients refuse to give consent for participation