Acute Coronary Syndromes
90 min
Door-to-Balloon
STEMI PCI target
12 hours
Troponin Peak
Peak elevation time
10 min
First ECG
Time to 12-lead
The ACS Spectrum
it is a continuum, not three separate diseasesUnstable Angina
ECG ST depression or T-wave changes
Troponin Negative
NSTEMI
ECG ST depression, T-wave inversion
Troponin Elevated
STEMI
ECG ST elevation ≥1mm in 2+ contiguous leads
Troponin Elevated
Troponin rises 3-6 hours after injury, peaks at 12-24 hours, and remains elevated for 7-14 days. A single negative troponin does not rule out ACS. Serial troponins are essential.
Treatment Priorities
12-lead ECG within 10 minutes of arrival
Aspirin 162-325 mg chewed immediately
STEMI → emergent PCI within 90 minutes (door-to-balloon)
NSTEMI → risk stratify, anticoagulation, possible early invasive strategy
P2Y12 inhibitor (clopidogrel, ticagrelor, prasugrel)
Heparin (unfractionated or LMWH)
Beta-blockers (avoid if hypotensive, bradycardic, or in acute HF)
Nitroglycerin is CONTRAINDICATED in right ventricular infarction because it drops preload, which the RV desperately needs to maintain output.
Key Values to Memorize
Door-to-ECG ≤10 min
Door-to-balloon ≤90 min
Troponin rise 3-6 hrs
Troponin peak 12-24 hrs
ASA 162-325 mg chewed
New LBBB = STEMI equivalent
you know the pathophysiology, now prove it under pressure
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Practice CCRN QuestionsExam Traps
MONA is outdated
Oxygen is only indicated if SpO2 falls below 94%. Morphine should be used cautiously as it may increase mortality in some ACS presentations. The exam tests whether you still follow the old MONA protocol blindly.
Nitroglycerin is contraindicated in RV infarct
Right ventricular infarction depends on preload. Nitroglycerin drops preload and can cause profound hypotension. If you see inferior MI with hypotension, clear lungs, and JVD, think RV involvement and hold the nitro.
Troponin alone does not diagnose ACS
Troponin can be elevated in PE, myocarditis, sepsis, renal failure, and heart failure. It must be interpreted alongside clinical presentation, ECG changes, and trending values.
New LBBB equals STEMI equivalent
A new left bundle branch block in the setting of chest pain should be treated as a STEMI equivalent. Do not wait for classic ST elevation when LBBB is new.
RV Infarct Red Flag
Inferior MI + hypotension + clear lungs + JVD = right ventricular infarct. Give fluids, NOT nitro.
Troponin Timeline
Troponin rises 3-6 hours, peaks 12-24, stays elevated 7-14 days. Know the timeline.
A coronary artery is a pipe feeding water to a section of the house. A clot blocks the pipe. Everything downstream starts dying from the moment flow stops.
Muscle tissue begins dying within minutes. The longer the blockage, the more muscle dies. That is why door-to-balloon time matters so much. Every minute of delay is more dead heart muscle.
PCI is like a plumber threading a wire through the clog and inflating a tiny balloon to reopen the pipe. Fibrinolytics dissolve the clog chemically. Either way, you are racing the clock.
Unstable angina = pipe is narrowing dangerously. NSTEMI = partial blockage with some damage. STEMI = complete blockage with major damage. The severity increases across the spectrum.
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