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Rapid Review·Cardiovascular

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Coronary Artery Disease

T1Must know

Acute Coronary Syndrome

Focus on

ECG and troponin sort unstable angina, NSTEMI and STEMI. Everyone gets aspirin, a P2Y12 inhibitor, anticoagulation, a statin and (if safe) a beta blocker. STEMI goes to PCI within 90 minutes or gets lytics within 12 hours; NSTE-ACS gets catheterization within 24 to 72 hours by risk and never fibrinolysis. Then the right ventricular infarct, the stent rules, and the discharge list.

Key takeaways

Three syndromes, one spectrum

Sorting acute coronary syndrome: the electrocardiogram comes first. ST elevation means ST-elevation MI. Without ST elevation, cardiac biomarkers decide: raised means non-ST-elevation MI, normal means unstable angina.
What this shows
Sorting acute coronary syndrome: the electrocardiogram comes first. ST elevation means ST-elevation MI. Without ST elevation, cardiac biomarkers decide: raised means non-ST-elevation MI, normal means unstable angina.

Acute coronary syndrome (ACS)

ischemic chest pain lasting over 20 minutes that does not settle with rest; it spans unstable angina and myocardial infarction (MI).
  • The electrocardiogram (ECG) and troponin split it into three syndromes, as in the ACS table.

Unstable angina

ischemic symptoms with a normal troponin and no ST elevation.

Non-ST-elevation myocardial infarction (NSTEMI)

ischemic symptoms with an elevated troponin and no ST elevation.
  • Unstable angina and NSTEMI share the same ECG picture: ST depression, T-wave inversion, or non-specific changes.

ST-elevation myocardial infarction (STEMI)

ST elevation on the ECG, which means the infarct is transmural.

Clinical features

Where ischemic chest pain is felt. Most common (left): substernal, left chest and arm, neck and jaw. Other sites (right): right chest and arm, epigastrium, and between the shoulder blades on the back.
What this shows
Where ischemic chest pain is felt. Most common (left): substernal, left chest and arm, neck and jaw. Other sites (right): right chest and arm, epigastrium, and between the shoulder blades on the back.

Acute retrosternal pressure

dull or squeezing, at rest or with less effort than the patient's usual angina.
  • It commonly radiates to the arm, shoulder, neck, jaw or epigastrium.
  • It may be precipitated by exertion or stress.

Associated symptoms

dyspnea (especially with exertion), pallor, nausea, vomiting, diaphoresis, anxiety (a sense of impending doom), lightheadedness or syncope.

Examination

may show tachycardia, an arrhythmia, a new S4, or signs of heart failure or cardiogenic shock.

Silent or atypical presentations

in diabetics, women and the elderly, as on the atypical figure.

Diagnosis

Evaluation of suspected acute coronary syndrome in the emergency department: ECG and troponin first. ST-elevation MI or new LBBB goes to urgent reperfusion; other ischemic changes or a raised troponin are admitted for further management; negative findings get serial ECG and troponin, and if those stay negative, a noninvasive stress test.
What this shows
Evaluation of suspected acute coronary syndrome in the emergency department: ECG and troponin first. ST-elevation MI or new LBBB goes to urgent reperfusion; other ischemic changes or a raised troponin are admitted for further management; negative findings get serial ECG and troponin, and if those stay negative, a noninvasive stress test.

ECG within 10 minutes of arrival

it is the gold standard in the first 6 hours.
  • The first ECG has poor sensitivity, so if it is normal, repeat it every 15 to 30 minutes with serial troponin until the picture resolves or confirms.
  • If both stay normal but suspicion is high, order a non-invasive stress test.

STEMI criteria

ST elevation in 2 or more contiguous leads, or a new left bundle branch block (LBBB) with ischemic symptoms (this rules in STEMI even without ST elevation).
Timeline of ECG changes in STEMI. Seconds to minutes: hyperacute T waves. Minutes to hours: ST elevation. Hours to days: small R waves, T-wave inversion and pathological Q waves. Weeks to years: variable resolution, with Q waves often persisting.
What this shows
Timeline of ECG changes in STEMI. Seconds to minutes: hyperacute T waves. Minutes to hours: ST elevation. Hours to days: small R waves, T-wave inversion and pathological Q waves. Weeks to years: variable resolution, with Q waves often persisting.

ECG timeline

hyperacute T waves come first, then ST elevation.
  • Pathologic Q waves (persistent, broad and deep) or poor R-wave progression mark an old infarct.

Troponin I

the preferred marker (most sensitive and specific).
  • A value above the 99th percentile is positive, and it stays elevated for days.

Reinfarction

diagnosed by a troponin rise of 20 percent or more within 3 to 6 hours plus new symptoms or ECG change; a single value cannot do it.
  • Creatine kinase-MB (CK-MB) was the old reinfarction marker because it normalizes by 48 hours.

Inferior ST elevation mandates right-sided leads (V4R)

to look for right ventricular infarction.

Posterior MI

ST depression in V1 to V3 with tall R waves; confirm it with ST elevation in V7 to V9.
STEMI location by leads
LeadsArteryWall
V1 to V2Left anterior descending (LAD)Anteroseptal
V3 to V4LADAnteroapical
I, aVL, V5 to V6Left circumflex (LCX)Lateral
II, III, aVFRight coronary artery (RCA)Inferior
Tall R with ST depression in V1 to V3 (ST elevation in V7 to V9)Posterior descending artery (PDA)Posterior
V4R with inferior changesRCARight ventricle

Immediate treatment and reperfusion

Initial stabilization of acute STEMI: oxygen if saturation is below 90% or dyspnea, aspirin 325 mg, a P2Y12 inhibitor, sublingual nitrates, a beta blocker (unless hypotension, bradycardia, acute heart failure or heart block), a high-dose statin and anticoagulation. Then IV nitroglycerin, IV morphine, IV atropine or IV furosemide for persistent pain, severe pain, unstable bradycardia or pulmonary edema, and reperfusion (PCI within 90 minutes, thrombolysis if PCI is not available within 120 minutes).
What this shows
Initial stabilization of acute STEMI: oxygen if saturation is below 90% or dyspnea, aspirin 325 mg, a P2Y12 inhibitor, sublingual nitrates, a beta blocker (unless hypotension, bradycardia, acute heart failure or heart block), a high-dose statin and anticoagulation. Then IV nitroglycerin, IV morphine, IV atropine or IV furosemide for persistent pain, severe pain, unstable bradycardia or pulmonary edema, and reperfusion (PCI within 90 minutes, thrombolysis if PCI is not available within 120 minutes).

Immediate management for everyone (MONA-BASH)

eight parts.
  • Morphine: only if pain persists.
  • Oxygen: only if oxygen saturation (SpO2) is below 90 percent.
  • Nitroglycerin: with caution in hypotension (for example right ventricular infarction).
  • Antiplatelets: chewed aspirin plus a P2Y12 inhibitor (ticagrelor or clopidogrel) for every patient.
  • Beta blocker (oral): contraindicated in cardiogenic shock, hypotension, bradycardia or heart failure.
  • Angiotensin-converting enzyme (ACE) inhibitor: within the first 24 hours; it limits post-MI remodeling.
  • High-intensity statin.
  • Heparin.

Reperfusion (STEMI)

primary percutaneous coronary intervention (PCI) within 90 minutes (120 minutes if the patient must be transferred).
  • If PCI cannot happen within 120 minutes, give fibrinolysis (tenecteplase or alteplase) within 12 hours of symptom onset.
  • Fibrinolysis is contraindicated with a prior intracranial hemorrhage, a recent ischemic stroke, blood pressure above 185/110, or active bleeding.
Management of unstable angina and NSTEMI by the TIMI risk score (1 point each: age 65 or more, 3 or more CAD risk factors, known stenosis over 50%, aspirin in the past 7 days, 2 or more anginal episodes in 24 hours, raised biomarkers, ST deviation over 0.5 mm). Low risk (0 to 2): stress test. Intermediate or high (3 to 7): early angiography within 24 hours. Instability, heart failure or new mitral regurgitation, recurrent pain or ventricular arrhythmia: immediate angiography.
What this shows
Management of unstable angina and NSTEMI by the TIMI risk score (1 point each: age 65 or more, 3 or more CAD risk factors, known stenosis over 50%, aspirin in the past 7 days, 2 or more anginal episodes in 24 hours, raised biomarkers, ST deviation over 0.5 mm). Low risk (0 to 2): stress test. Intermediate or high (3 to 7): early angiography within 24 hours. Instability, heart failure or new mitral regurgitation, recurrent pain or ventricular arrhythmia: immediate angiography.

Reperfusion (unstable angina and NSTEMI)

risk-stratify with the Thrombolysis in Myocardial Infarction (TIMI) score, then cardiac catheterization (diagnostic and therapeutic) within 24 to 72 hours.
  • Go immediately to PCI only with shock or hemodynamic instability, ventricular arrhythmia, or refractory chest pain.
  • Fibrinolysis is never given for unstable angina or NSTEMI.

Special situations

three that change the plan.
  • Pulmonary edema: intravenous (IV) furosemide unless the patient is hypotensive, and avoid beta blockers.
  • Unstable bradycardia after an inferior MI: IV atropine, then a pacemaker if unresponsive; it is usually transient.
  • Heart block after an anterior MI: reflects structural damage, so it will not respond to atropine and needs pacing.

Right ventricular infarction

Usually accompanies an inferior MI

from RCA occlusion.

Classic triad

hypotension, raised jugular venous pressure (JVP), and clear lungs.
Right-sided ECG: the precordial leads are placed in a mirror image across the right chest (V4R at the right fifth intercostal space in the midclavicular line). ST elevation in V4R is highly accurate for right ventricular infarction.
What this shows
Right-sided ECG: the precordial leads are placed in a mirror image across the right chest (V4R at the right fifth intercostal space in the midclavicular line). ST elevation in V4R is highly accurate for right ventricular infarction.

Confirm with ST elevation in V4R

the right-sided leads are placed as a mirror image of the usual chest leads.
  • See also the Read the posterior-inferior STEMI pattern.

Bradycardia and atrioventricular (AV) block are common

because the RCA supplies the AV node.

Treat with IV fluids

the right ventricle is preload-dependent.

Stents and long-term treatment

Bare-metal versus drug-eluting stent: the bare-metal stent endothelializes early (shorter thrombotic risk period, higher risk of restenosis); the drug-eluting stent endothelializes late (longer thrombotic risk period, lower risk of restenosis). Drug-eluting stents reduce neointimal restenosis but make uninterrupted antiplatelet planning essential.
What this shows
Bare-metal versus drug-eluting stent: the bare-metal stent endothelializes early (shorter thrombotic risk period, higher risk of restenosis); the drug-eluting stent endothelializes late (longer thrombotic risk period, lower risk of restenosis). Drug-eluting stents reduce neointimal restenosis but make uninterrupted antiplatelet planning essential.

An MI after PCI is usually stent thrombosis

acute clot inside the stent, presenting as a STEMI.
  • Premature discontinuation of antiplatelet therapy is the strongest predictor.
  • Treat as a STEMI and go back to PCI.

Bare-metal stents (BMS)

endothelialize early, so their risk is early thrombosis.

Drug-eluting stents (DES)

endothelialize late, so their risk is late (over 1 month) and very late (over 1 year) thrombosis.
  • They need dual antiplatelet therapy (DAPT) for much longer.

In-stent restenosis

angina that returns gradually months after a stent; rare with a DES.

Long-term treatment

the goal is secondary prevention.
  • Continue the antiplatelets, beta blocker, ACE inhibitor or angiotensin receptor blocker (ARB), and high-intensity statin.
  • DAPT for 12 months regardless of stent placement, then aspirin for life.
  • Add spironolactone when the left ventricular ejection fraction (LVEF) is below 40 percent with heart failure or diabetes.
  • Cardiac rehabilitation.

Complications

ventricular fibrillation is the most common cause of death in the first 24 hours.
  • The mechanical ruptures, aneurysm, pericarditis and Dressler syndrome follow a clock (Post MI Complications).
  • Livedo, blue toes and a rising creatinine after catheterization is atheroembolism (Cholesterol Embolism Syndrome).
Inferior ST elevation with hypotension, raised JVP and clear lungs. What else is infarcted, how is it confirmed, and which common ACS drug is dangerous here?

The right ventricle (RCA occlusion). Confirm with ST elevation in V4R on right-sided leads. The right ventricle is preload-dependent, so give IV fluids and avoid nitrates (and morphine and diuretics), which drop preload and cause severe hypotension.

How it's tested

Crushing chest pain, ST elevation in V1 to V4, at a PCI-capable hospital: aspirin, ticagrelor, heparin, and the cath lab within 90 minutes; troponin does not gate this.

Same picture at a rural hospital 3 hours from a cath lab, onset 2 hours ago, no contraindication: fibrinolysis within 30 minutes, then transfer.

Chest pain with ST depression and a positive troponin: NSTEMI; aspirin, P2Y12 inhibitor, heparin, statin, beta blocker; catheterization within 24 hours; fibrinolysis is wrong.

Inferior STEMI with a blood pressure of 80/50, raised neck veins and clear lungs: right ventricular infarction; V4R, IV fluids, no nitrates.

Two months after a DES a man stops clopidogrel before a dental extraction and develops ST elevation in the stented territory: stent thrombosis; emergency catheterization, not a stress test.

Which stent for a patient scheduled for a cancer operation in six weeks: a bare-metal stent or balloon angioplasty, because a DES needs months of uninterrupted DAPT.

Post-MI day 2, EF 30 percent, potassium 4.5, creatinine normal: add eplerenone to the ACE inhibitor and beta blocker; an ICD only if the EF is still 35 percent or less after 40 days.

Go deeper

Guidelines: 2025 ACC/AHA Acute Coronary Syndromes Guideline

Related Step 2 pages: Post MI Complications, Stable Angina, Cholesterol Embolism Syndrome, Cardiogenic Shock, Atrioventricular Block, Heart Failure, Approach to Chest Pain

High-yield images12
Posterior-inferior STEMI: inferior ST elevation with reciprocal anterior ST depression; evaluate for RCA-associated AV nodal block and right-ventricular involvement.
Bare-metal versus drug-eluting stent: the bare-metal stent endothelializes early (shorter thrombotic risk period, higher risk of restenosis); the drug-eluting stent endothelializes late (longer thrombotic risk period, lower risk of restenosis). Drug-eluting stents reduce neointimal restenosis but make uninterrupted antiplatelet planning essential.
Acute coronary syndromes compared: STEMI (ST elevation in 2 or more contiguous leads) needs emergency reperfusion such as PCI; non-STEMI (troponin raised) and unstable angina (a consistent history such as rest angina, troponin not raised) get medical management first and reperfusion within 24 hours.
Cardinal symptoms of acute coronary syndrome (left: retrosternal pain spreading to the left arm, shoulder, neck, jaw and epigastrium, with diaphoresis, a sense of doom, nausea and dyspnea) beside the nonspecific warning signs more common in women (right: dizziness, fatigue, jaw, neck or upper back pain, palpitations, epigastric discomfort).
Evaluation of suspected acute coronary syndrome in the emergency department: ECG and troponin first. ST-elevation MI or new LBBB goes to urgent reperfusion; other ischemic changes or a raised troponin are admitted for further management; negative findings get serial ECG and troponin, and if those stay negative, a noninvasive stress test.
Timeline of ECG changes in STEMI. Seconds to minutes: hyperacute T waves. Minutes to hours: ST elevation. Hours to days: small R waves, T-wave inversion and pathological Q waves. Weeks to years: variable resolution, with Q waves often persisting.
Management of unstable angina and NSTEMI by the TIMI risk score (1 point each: age 65 or more, 3 or more CAD risk factors, known stenosis over 50%, aspirin in the past 7 days, 2 or more anginal episodes in 24 hours, raised biomarkers, ST deviation over 0.5 mm). Low risk (0 to 2): stress test. Intermediate or high (3 to 7): early angiography within 24 hours. Instability, heart failure or new mitral regurgitation, recurrent pain or ventricular arrhythmia: immediate angiography.
Initial stabilization of acute STEMI: oxygen if saturation is below 90% or dyspnea, aspirin 325 mg, a P2Y12 inhibitor, sublingual nitrates, a beta blocker (unless hypotension, bradycardia, acute heart failure or heart block), a high-dose statin and anticoagulation. Then IV nitroglycerin, IV morphine, IV atropine or IV furosemide for persistent pain, severe pain, unstable bradycardia or pulmonary edema, and reperfusion (PCI within 90 minutes, thrombolysis if PCI is not available within 120 minutes).
Posterior-inferior STEMI: ST elevation in II, III and aVF (inferior wall), ST depression in V1 and V2 (posterior wall) with reciprocal changes, and 2:1 AV block; most often from right coronary artery occlusion, less often the circumflex.
Sorting acute coronary syndrome: the electrocardiogram comes first. ST elevation means ST-elevation MI. Without ST elevation, cardiac biomarkers decide: raised means non-ST-elevation MI, normal means unstable angina.
Where ischemic chest pain is felt. Most common (left): substernal, left chest and arm, neck and jaw. Other sites (right): right chest and arm, epigastrium, and between the shoulder blades on the back.
Right-sided ECG: the precordial leads are placed in a mirror image across the right chest (V4R at the right fifth intercostal space in the midclavicular line). ST elevation in V4R is highly accurate for right ventricular infarction.

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# What intervention is most likely to improve cardiovascular and overall long-term mortality in patients with acute STEMI? 

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