How is acute coronary syndrome (ACS) treated?

Updated: Sep 30, 2020
  • Author: David L Coven, MD, PhD; Chief Editor: Eric H Yang, MD  more...
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Initial therapy for ACS should focus on stabilizing the patient's condition, relieving ischemic pain, and providing antithrombotic therapy to reduce myocardial damage and prevent further ischemia. Morphine (or fentanyl) for pain control, oxygen, sublingual or intravenous (IV) nitroglycerin, soluble aspirin 162-325 mg, and clopidogrel with a 300- to 600-mg loading dose are given as initial treatment.

In complete vessel occlusion without collateralization of the infarct-related vessel, there is little utility in “pushing nitrates.”

High-risk patients with non-ST-segment elevation myocardial infarction (NSTEMI ACS) should receive aggressive care, including aspirin, clopidogrel, unfractionated heparin or low–molecular-weight heparin (LMWH), IV platelet glycoprotein IIb/IIIa complex blockers (eg, tirofiban, eptifibatide), and a beta blocker. The goal is early revascularization.

Intermediate-risk patients with NSTEMI ACS should rapidly undergo diagnostic evaluation and further assessment to determine their appropriate risk category.

Low-risk patients with NSTEMI ACS should undergo further follow-up with biomarkers and clinical assessment. Optimal medical therapies include use of standard medical therapies, including beta blockers, aspirin, and unfractionated heparin or LMWH. The Clopidogrel in Unstable Angina to Prevent Recurrent Events (CURE) study showed that clopidogrel would be beneficial even in low-risk patients. [53] If no further pain occurs, and follow-up studies are negative, a stress study should drive further management.

Monitor and immediately treat arrhythmias in the first 48 hours. Pay attention to exacerbating factors, such as disturbances in electrolytes (especially potassium and magnesium), hypoxemia, drugs, or acidosis. Correct these factors accordingly.

Humidified oxygen may reduce the risk of nosebleeds in patients with ACS who are receiving antiplatelet and antithrombin therapy.

Do not administer nitrates if the patient is hypotensive (systolic BP < 90 mm Hg); if RV infarction, large pericardial effusion, or severe aortic stenosis is suspected; or if the patient recently received phosphodiesterase-5 inhibitors (eg, sildenafil).

Patients with known hypersensitivity to antiplatelet agents, active internal bleeding, and bleeding disorders should not receive antiplatelet or antithrombotic therapy.

Some patients with intractable chest pain or severe hypotension may require the insertion of an intra-aortic balloon pump. The EuroHeart survey showed a nearly 40% reduction in the risk of death in patients with ACS who received support with an intra-aortic balloon pump. This benefit was independent of the status of the ST segment.

Congestive heart failure (CHF) can be due to systolic dysfunction or diastolic dysfunction in the setting of myocardial infarction. Aggressive treatment is indicated to prevent worsening of the situation.

Patients presenting with cardiogenic shock should undergo percutaneous coronary intervention (PCI) as soon as possible. Cardiogenic shock is associated with a high mortality rate. Pressor agents, such as dopamine, and inotropic agents, such as dobutamine, may be needed. In a prospective, natural-history study of coronary atherosclerosis, patients underwent 3-vessel coronary angiography and gray-scale and radiofrequency intravascular ultrasonographic imaging after PCI. [54]

Recurrent ischemia may be due to incomplete reperfusion. In the setting of PCI, consider stent thrombosis as a possible cause. Whether drug-eluting stents have an increased rate of thrombosis compared with bare metal stents is unclear.

The clinical significance of incomplete coronary revascularization (ICR) following PCI in patients with ACS was examined in 2,954 patients from the Acute Catheterization and Urgent Intervention Triage Strategy (ACUITY) trial. At one year follow-up, ICR was strongly associated with ischemia-driven unplanned revascularization, myocardial infarction and major adverse cardiac events. [55]

Drug-eluting stents are linked with fewer periprocedural risks but tend to have high incidence of postprocedural complications including myocardial infarction, repeat procedures, and 12-month major adverse cardiac and brain complications, compared with coronary bypass surgery. [56]

One study by Ribichini et al suggests that prednisone treatment after bare metal stents or drug-eluting stent implantation results in a better event-free survival at 1 year. [57]

In the final report of the HORIZONS-AMI trial, which assessed the 3 year outcomes of the effectiveness and safety of bivalirudin monotherapy and paclitaxel-eluting stenting, outcomes were sustained for patients with STEMI undergoing primary PCI. [58]

In a study of 3031 patients, Mehta et al found that early intervention (coronary angiography ≤24 h after randomization) in patients with ACS did not differ greatly from delayed intervention (coronary angiography ≥36 h randomization) in the prevention of primary outcomes (ie, composite of death, myocardial infarction, or stroke at 6 mo). Early intervention did reduce the rate of secondary outcomes (ie, death, myocardial infarction, or refractory ischemia at 6 mo) and improved primary outcomes in patients who were at highest risk (ie, GRACE risk score >140). [59]

In a Swedish registry of patients with STEMI from 1996-2007, reported an increase in the prevalence of evidence-based treatments. [60] The use of aspirin, clopidogrel, beta blockers, statins, and ACE inhibitors all increased. Clopidogrel increased from 0% to 82%, statins increased from 23% to 83%, and various ACE inhibitors increased by a large margin. A decrease was reported in 30-day and 1-year mortality that was sustained during long-term follow-up. By following the proper guidelines, patients who have experienced STEMI have higher survival rates.

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