MONA GAP Mnemonic for Acute Coronary Syndrome
What MONA GAP Stands For
The MONA GAP mnemonic is largely obsolete and should not guide contemporary ACS management, as several components lack mortality benefit and may cause harm 1, 2, 3.
The traditional mnemonic stands for:
- M = Morphine
- O = Oxygen
- N = Nitrates (Nitroglycerin)
- A = Aspirin
- G = Glycoprotein IIb/IIIa inhibitors
- A = ACE inhibitors
- P = P2Y₁₂ inhibitors (antiplatelet agents like clopidogrel, ticagrelor, prasugrel)
Critical Evidence Against MONA Components
Morphine: Reserved for Refractory Pain Only
Morphine should be reserved exclusively for patients with persisting severe chest pain despite other interventions, not given routinely 1. The 2015 ESC guidelines explicitly state morphine is for patients with "persisting severe chest pain" only 1. Emerging evidence suggests morphine may be associated with increased mortality and larger infarct size 2, 3. Morphine delays absorption of oral P2Y₁₂ inhibitors, potentially compromising antiplatelet efficacy 2.
Oxygen: Only for Hypoxemia
Oxygen therapy should be applied only when blood oxygen saturation is <90% or respiratory distress is present 1. Routine supplemental oxygen in normoxemic ACS patients is associated with increased infarct size and potentially higher mortality 2, 3. The ESC guidelines are unequivocal: oxygen is indicated for hypoxemia, not routinely 1.
Nitrates: Symptom Relief Without Mortality Benefit
Nitrates (sublingual or intravenous) are appropriate for persisting chest pain but provide no mortality benefit 1, 2, 3. The ESC guidelines recommend nitrates "if there is persisting chest pain" as an initial treatment measure 1. No randomized trial has demonstrated that nitrates reduce death or prevent infarction 2.
Components That DO Reduce Mortality
Aspirin: Immediate and Mandatory
Aspirin 162-325 mg loading dose should be given immediately to all ACS patients unless contraindicated 4. This is the only component of the original MONA with proven mortality benefit 3, 5.
P2Y₁₂ Inhibitors: Essential Dual Antiplatelet Therapy
A P2Y₁₂ inhibitor loading dose must be administered promptly: ticagrelor 180 mg, prasugrel 60 mg (if <75 years, >60 kg, no prior stroke), or clopidogrel 600 mg 1, 4. These agents reduce mortality when combined with aspirin 5.
Glycoprotein IIb/IIIa Inhibitors: High-Risk Patients Only
GP IIb/IIIa inhibitors (tirofiban or eptifibatide) should be considered in high-risk patients with elevated troponin or high-risk coronary anatomy undergoing PCI 1. Abciximab is reserved for high-risk patients immediately prior to PCI 1.
ACE Inhibitors: For Specific Indications
ACE inhibitors are recommended in patients with LVEF ≤40%, heart failure, hypertension, or diabetes 1. An ARB provides an alternative if ACE inhibitors are not tolerated 1.
Contemporary ACS Management Framework
The evidence-based approach prioritizes:
- Immediate reperfusion for STEMI (primary PCI within 90-120 minutes) 4
- Dual antiplatelet therapy (aspirin + P2Y₁₂ inhibitor) 1, 4
- Anticoagulation (UFH, enoxaparin, fondaparinux, or bivalirudin) 1
- Beta-blockers (mortality benefit in LVEF ≤40%) 1
- High-intensity statins (started early) 1
- Risk stratification (GRACE or TIMI score) to determine timing of invasive strategy 1, 4
Common Pitfalls
Do not give morphine or oxygen routinely—this practice persists despite guideline recommendations against it 1, 2. Do not delay P2Y₁₂ inhibitor administration while waiting for angiography in NSTE-ACS patients 1. Do not use GP IIb/IIIa inhibitors routinely—reserve them for high-risk patients during PCI 1.
The MONA mnemonic has been superseded by more comprehensive frameworks that include thienopyridines, anticoagulation, beta-blockers, statins, and evidence-based reperfusion strategies 5.