Author: William J Gibson MD, PhD

Patient presents with XX hour history of [substernal] chest pain that radiates to [jaw/arm], associated with [diaphoresis, shortness of breath]. EKG on admission showing XX. Troponin on admission XX and subsequently trended to XX XX hours later. [Most likely type 1 MI given abrupt onset, ST-segment elevation OR History suggests type 2 MI given high concern for supply-demand mismatch. Differential includes coronary dynamic/non-occlusive obstruction (including vasospasm, microvascular ischemia, Takutsubo cardiomyopathy, myocarditis), non-plaque associated thromboembolism (Afib, cardioversion, PFO), coronary dissection, vascular steal, vasculitis.

Dx:

– Serial EKG (Q30 mins initially), if STEMI

– Serial troponins (admission, 2H and 6H) if concern ACS rapidly evolving, 3x Q6H for rule-out (if 5th generation hsTn: Serial troponins Q3H sufficient)

Risk stratification:

– TIMI Risk Score (NSTEMI): https://www.mdcalc.com/timi-risk-score-ua-nstemi

– If GRACE Score > 140, early invasive strategy may be preferred (cath <72h [1]) http://www.outcomes.org/grace

– HbA1c, lipid panel

– Consider further risk stratification (stress test vs CT angio vs coronary angiography)

– TTE to rule out new wall motion abnormality

Tx:

– Treat any secondary causes of myocardial ischemia (eg AF w RVR, anemia, hypoxemia (only if O2sat <92%), infection)

Initial therapy:

– Anticoagulation/Anti-platelet: ASA (325), Heparin drip (goal PTTT 60-80), defer clopidogrel on admission given unclear if patient will need CABG

– Rate: Metoprolol 25mg PO Q6H, titrate to HR 50-60 (will hold if evidence of shock, AV-block)

– Pain: sublingual nitro PRN (caution if inferior MI), defer morphine given interference with P2Y12 inhibitors and retrospective analyses suggesting increased adverse events.

– Defer oxygen given randomized evidence of increased infarct size in STEMI without hypoxia [2]

– Lipids: Atorvastatin 80mg [3]

Long term: Plan for ASA 81mg QD, P2Y12 (preference: ticagrelor>prasugrel>clopidogrel), Beta blocker, Statin, ACE (esp if EF<40%)/ARB, consider spironolactone (RALES), ezetimibe (IMPROVE-IT), low-dose rivaroxaban (ATLAS-2), empagliflozin if DM (EMPA-REG).

Post-stenting:

– if stented will give clopidogrel 75mg PO QD (30 days of BMS, 1 year for DES)

References:

1. Mehta SR, Granger CB, Boden WE, et al. Early versus delayed invasive intervention in acute coronary syndromes. N Engl J Med. 2009;360(21):2165-75.
2. Stub D, Smith K, Bernard S, et al. Air Versus Oxygen in ST-Segment-Elevation Myocardial Infarction. Circulation. 2015;131(24):2143-50.
3. Cannon CP, Braunwald E, Mccabe CH, et al. Intensive versus moderate lipid lowering with statins after acute coronary syndromes. N Engl J Med. 2004;350(15):1495-504.