Introduction
- Complications after ACS can be divided by timing into acute complications and subacute-chronic complications.
- Though this delineation is generally true, these complications can occur earlier or later than expected.
- Acute (on presentation to days) complications:
- Cardiogenic shock from LV failure.
- Arrhythmias.
- Ischemic papillary muscle rupture.
- Ventricular septal defect (VSD).
- LV free wall rupture.
- Early pericarditis.
- Subacute-chronic (weeks or more) complications:
- LV thrombus.
- LV aneurysm.
- Late pericarditis.
Cardiogenic Shock from LV Failure
- Epidemiology: 5-10% of patients with ACS. High mortality. Typically within 1 day after STEMI and within several days after NSTEMI.
- Risk factors: anterior infarct, diabetes, older age, prior MI, multivessel disease, or left main disease.
- Physical exam: signs of heart failure with sustained hypotension and volume overload.
- Diagnosis: chest x-ray, echocardiography, right heart catheterization.
- Treatment: early revascularization, inotropic/pressor support, ventilatory support, mechanical circulatory support (see section Cardiogenic Shock).
Arrhythmias
- Both tachyarrhythmias and bradyarrhythmias can occur, typically on presentation to days after ACS.
- Tachyarrhythmias:
- Supraventricular: atrial fibrillation is the most common. See Atrial Fibrillation section for management. Specifically, avoid class I antiarrhythmics.
- Ventricular:
- Accelerated idioventricular rhythm is a common reperfusion arrhythmia which does not require treatment unless patient is symptomatic or hemodynamically unstable.
- Ventricular tachycardia:
- Within the first 48 hours after infarct is more likely due to increased automaticity in the region of ischemia/infarction. Treat with correction of acid/base status and electrolyte abnormalities, medical and/or interventional treatment of ongoing ischemia, and GDMT for any co-occurring HF.
- After the first 48 hours is more likely due to a reentrant circuit around scar. ICD placement is indicated before discharge (if VT episode not due to electrolyte or acid/base abnormalities, transient ischemia, or reinfarction).
Papillary Muscle Rupture
- Epidemiology: <1% of patients, typically within a week after ACS.
- Risk factors: inferior MI (single blood supply to posteromedial papillary muscle), large infarct, poor collateral circulation, first infarct, diabetes, older women. Can result from a relatively small or clinically unapparent MI.
- Physical exam: new systolic murmur (loudest at the apex, radiating to the axilla), intensity of the murmur does not correlate to severity of mitral regurgitation.
- Diagnosis: echocardiogram.
- Treatment: urgent surgery. Temporary stabilization with medical therapy may be needed, including afterload reduction with vasodilator or IABP.
Ventricular Septal Defect
- Epidemiology: <1% of patients, typically within a week after ACS.
- Risk factors: large infarct, single vessel disease, poor collateral circulation, first infarct, diabetes, older women.
- Physical exam: holosystolic murmur loudest over LLSB as well as thrill.
- Diagnosis: echocardiography, right heart cath.
- Treatment: emergent surgical repair. Temporary stabilization with medical therapy may be needed, including afterload reduction with vasodilator, inotropes, mechanical circulatory support.
LV Free Wall Rupture
- Epidemiology: <1% of patients in the modern reperfusion era, typically within a week after ACS.
- Risk factors: transmural MI, first MI, anterior infarct, lack of collaterals, no or delayed reperfusion, female gender, steroids, NSAIDs.
- Physical exam: acute decompensation related to cardiac tamponade (hypotension, elevated JVP, diminished heart sounds, pulsus paradoxus). Acutely, a small effusion can cause severe tamponade.
- Diagnosis: echocardiography, right heart cath.
- Treatment: emergent surgical repair.
Early Pericarditis
- Epidemiology: 10% of patients with acute MI, typically within days after ACS.
- Risk factors: transmural MI.
- Symptoms: sharp, stabbing pain, worse while supine and with inspiration, radiating to trapezius.
- Physical exam: pericardial friction rub in 85% of patients.
- Diagnosis: EKG may show evidence of pericarditis, echo may reveal pericardial effusion.
- Treatment: aspirin and consider colchicine. Avoid NSAIDs and corticosteroids (may interfere with healing of infarcted myocardium). Avoid heparin to reduce risk of hemorrhagic transformation of pericardial effusion.
LV Thrombus
- Epidemiology: 5-10% of patients after PCI for ACS, typically occurs within two weeks after ACS.
- Risk factors: anterior MI, large MI, LV aneurysm.
- Complications: embolization risk.
- Diagnosis: sensitivity for LV thrombus CMR > TEE > TTE. Echo contrast can improve diagnostic accuracy.
- Treatment: anticoagulation with heparin bridge to warfarin, goal INR 2-3. Duration of anticoagulation varies, but patients will need serial imaging to assess for resolution of thrombus usually in 3 month intervals.
LV Aneurysm
- Epidemiology: <5% of patients with STEMI (though 10-30% if no reperfusion), typically in the days to weeks after ACS.
- Risk factors: anterior MI, steroids, NSAIDs.
- Physical exam: diffuse, displaced point of maximal impulse (PMI), ± S3 and/or S4.
- Diagnosis: EKG (Q waves in V1-3 with persistent ST elevation), echo, cardiac MRI. Make sure to distinguish it from a pseudoaneursym which has a higher risk for rupture and needs surgical attention.
- Treatment: anticoagulation with heparin/warfarin if mural thrombus present.
Late Pericarditis (Dressler's Syndrome)
- Epidemiology: 1-3% of patients with acute MI, typically within weeks-months after ACS.
- Etiology: thought to be secondary to immune-mediated injury.
- Physical exam: pericardial friction rub, fever.
- Diagnosis: EKG may show evidence of pericarditis, echo may show pericardial effusion.
- Treatment: aspirin and consider colchicine. If >4 weeks after MI, can use NSAIDs (ibuprofen preferred, indomethacin may diminish coronary blood flow); corticosteroids are second-line.
References
Hohnloser SH, Kuck KH, Roberts RS et al. Prophylactic Use of an Implantable Cardioverter–Defibrillator after Acute Myocardial Infarction. N Engl J Med 2004; 351:2481-2488.
Ibanez, Borja, et al. "2017 ESC Guidelines for the management of acute myocardial infarction in patients presenting with ST-segment elevation: The Task Force for the management of acute myocardial infarction in patients presenting with ST-segment elevation of the European Society of Cardiology (ESC)." European heart journal 39.2 (2018): 119-177.
O’Gara PT, et al. 2013 ACCF/AHA Guideline for the Management of ST-Elevation Myocardial Infarction. J Am Coll Cardiol. 2013;61(4)e78-e140.