A Pilot Randomized Controlled Trial of Intravenous N-acetyl Cysteine in STEMI

Patients presenting with ST-segment elevation myocardial infarction within 3 hours of symptom onset and satisfying all of the inclusion criteria after informed consent would be randomly allocated to either intravenous N-Acetylcysteine or standard treatment using a 1:1 allocation ratio. Those randomized to IV N-Acetylcysteine would be administered a bolus of 1200 mg over 0.5 hours (in 5% Dextrose) followed by 600mg/hour for the remaining 47.5 hours (in 5% dextrose). A total N-acetylcysteine dose of 29.7 grams is administered over 48 hours. The infusion is continued during the primary percutaneous coronary intervention. Patients would be followed up for a minimum of 90 days. The primary clinical endpoint will be myocardial infarct size measured by late gadolinium enhancement CMR imaging at 3-5 days from first medical contact. Primary feasibility outcome will be the rate of recruitment, the number of patients undergoing cardiac MRI within the stipulated time frame, and completeness of the study data collection.

Inclusion criteria

Patients presenting with STEMI within 3 hours of symptom onset and satisfying all of the following criteria:

• Patient age ≥ 18 years
• Have received thrombolysis, with intend to pursue a pharmaco-invasive reperfusion strategy. Onset of chest pain to reperfusion time of < 3hrs.
• STEMI involving anterior and/or inferior wall
• An absence of baseline Q-waves on the initial ECG: The presence of Q waves defined at baseline using the Selvester QRS screening criteria
• Have a high-risk STEMI ECG defined as:

• ≥2mm ST-segment elevation in 2 anterior or lateral leads; or
• ≥2 mm ST-segment elevation in 2 inferior leads coupled with ST-segment depression in 2 contiguous anterior leads for a total ST-segment deviation of ≥4 mm

Exclusion criteria

• Previous myocardial infarction
• Known to have moderate to severe LV systolic dysfunction (LV EF< 45%)
• Known allergy to thrombolytic therapy or NAC
• Presence of left bundle branch block
• Cardiogenic shock (defined as systolic blood pressure of < 90mm Hg, for at least 30 minutes, not responsive to fluid resuscitation)
• Permanent pacemaker or cardioverter defibrillator implanted previously
• Patients with contra-indications to thrombolytic therapy
• Patients with loss of consciousness or confusion
• Patients with known chronic kidney disease (GFR < 30ml/min/m2) or on dialysis
• Current pregnancy
• Planned therapy with primary PCI