STEMI Definition
ST elevation ≥ 1 mm in 2 contiguous leads (≥ 2 mm V2-V3 in men)
Revascularization Window
PCI door-to-balloon < 90 min (or fibrinolytics < 30 min)
Dual Antiplatelet Therapy
Aspirin + P2Y12 inhibitor (ticagrelor/clopidogrel) for 12 months
OMM Autonomic Arc
Sympathetics T1–T5; Parasympathetics Vagus (CN X)
ACS Classification & Pathophysiology
Acute Coronary Syndrome results from acute coronary thrombosis precipitated by atherosclerotic plaque rupture or erosion:
STEMI
Complete transmural coronary occlusion. Presents with ST elevations or new LBBB. Elevated troponins. Requires immediate emergency reperfusion.
NSTEMI
Subendocardial ischemia with incomplete occlusion. ST depressions and/or T-wave inversions. Elevated cardiac troponin confirms myocardial necrosis.
Unstable Angina
Subendocardial ischemia without necrosis. Ischemic ECG changes may be present, but troponins are normal.
12-Lead ECG Coronary Territory Localization
Board questions expect instant identification of the culprit vessel based on leads:
| Infarct Territory | ECG Leads with ST Elevation | Culprit Coronary Artery | High-Yield Board Associations |
|---|---|---|---|
| Anterior / Septal | V1, V2, V3, V4 | LAD (Left Anterior Descending) | Highest mortality; cardiogenic shock; bundle branch blocks |
| Lateral | I, aVL, V5, V6 | LCx (Left Circumflex) | May present with minimal precordial changes |
| Inferior | II, III, aVF | RCA (Right Coronary Artery) | Bradycardia, AV blocks; check right-sided leads (V4R) |
| Right Ventricular | V4R (ST elevation in V4R) | Proximal RCA | Preload dependent! Avoid nitrates/diuretics! Treat with IV fluids |
| Posterior | Tall R waves & ST depressions V1-V3 | PDA / LCx / RCA | Mirror image of anterior STEMI; place posterior leads V7-V9 |
Step-by-Step ACS Management Protocol
Immediate interventions for all suspected ACS presentations:
Initial Resuscitation (MONA B)
1. Aspirin: 325 mg chewable immediately (reduces mortality).
2. P2Y12 Inhibitor: Ticagrelor or prasugrel or clopidogrel load.
3. Anticoagulation: Unfractionated heparin or enoxaparin.
4. Nitroglycerin: Sublingual for chest pain (CONTRAINDICATED in RV infarct or PDE-5 inhibitor use).
5. High-intensity Statin: Atorvastatin 80 mg.
6. Beta-blocker: Metoprolol within 24h unless signs of acute heart failure or bradycardia.
2. P2Y12 Inhibitor: Ticagrelor or prasugrel or clopidogrel load.
3. Anticoagulation: Unfractionated heparin or enoxaparin.
4. Nitroglycerin: Sublingual for chest pain (CONTRAINDICATED in RV infarct or PDE-5 inhibitor use).
5. High-intensity Statin: Atorvastatin 80 mg.
6. Beta-blocker: Metoprolol within 24h unless signs of acute heart failure or bradycardia.
Reperfusion Strategies
Primary Percutaneous Coronary Intervention (PCI) is gold standard. Door-to-balloon time < 90 min at PCI center (< 120 min if transfer required). If PCI unavailable within 120 min: Fibrinolysis (Alteplase/Tenecteplase) within 30 min of arrival.
COMLEX / OMM Integration
NBOME High-Yield Correlate
Cardiovascular OMM Reflexes & Autonomics
- Sympathetic Innervation: Pre-ganglionic neurons arise from
- Parasympathetic Innervation: Vagus nerve (CN X).
- Anterior Chapman Reflex:
- Posterior Chapman Reflex: Between the transverse processes of
T1–T5. Post-ganglionic cardiac nerves increase inotropy, chronotropy, and ventricular irritability. Right-sided sympathetics supply the SA node (supraventricular tachycardias); left-sided sympathetics supply the AV node (ectopic ventricular arrhythmias).- Parasympathetic Innervation: Vagus nerve (CN X).
- Anterior Chapman Reflex:
2nd intercostal space, adjacent to the sternum.- Posterior Chapman Reflex: Between the transverse processes of
T2 and T3.
Board Traps & Common Distractors
- Trap: Giving nitrates to a patient with an Inferior STEMI without checking right-sided leads (V4R). If RV infarct is present, nitrates cause profound refractory hypotension!
- Trap: Using beta-blockers in acute cocaine-induced chest pain (risk of unopposed alpha-1 vasoconstriction). Treat cocaine chest pain with benzodiazepines and nitrates.