Overview of Revascularization for Acute Coronary Syndromes

Immediate reperfusion is not as urgent in patients with uncomplicated non–ST-segment elevation myocardial infarction (NSTEMI), in whom a completely occluded infarct-related artery at presentation is uncommon, or in patients with unstable angina who respond to medical therapy. Such patients typically undergo angiography within the first 24 to 48 hours of hospitalization to identify coronary lesions requiring PCI or CABG.

A noninterventional approach and a trial of medical management are used for patients in whom angiography demonstrates

• Only a small area of myocardium at risk

• Lesion morphology not amenable to PCI

• Anatomically insignificant disease (< 50% coronary stenosis)

• Significant left main disease in patients who are not candidates for CABG

Further, angiography or PCI should be deferred in favor of medical management for patients with a high risk of procedure-related morbidity or mortality.

By contrast, patients with persistent chest pain despite maximal medical therapy or complications (eg, markedly elevated cardiac biomarkers, presence of cardiogenic shock, acute mitral regurgitation, ventricular septal defect, unstable arrhythmias) should proceed directly to the cardiac catheterization laboratory to identify coronary lesions requiring PCI or CABG.

As in patients with stable angina, CABG has historically been preferred over PCI for patients with left main or left main equivalent disease (although the data supporting this practice are changing) and for those with left ventricular dysfunction or diabetes. CABG must also be considered when PCI is unsuccessful, cannot be used (eg, in lesions that are long or near bifurcation points), or causes acute coronary artery dissection.

Fibrinolytics are not indicated for unstable angina or NSTEMI. Risk outweighs potential benefit.

Emergency PCI is the preferred treatment of ST-segment elevation myocardial infarction (STEMI) when available in a timely fashion (door to balloon-inflation time < 90 minutes) by an experienced operator (1). Indications for urgent PCI later in the course of STEMI include hemodynamic instability, malignant arrhythmias requiring transvenous pacing or repeated cardioversion, and age > 75 years. If the lesions necessitate CABG, there is significant mortality and a higher morbidity rate.

If there is likely to be a significant delay in availability of PCI, thrombolysis should be done for STEMI patients meeting criteria (see table Fibrinolytic Therapy for STEMI

Regardless, most patients who undergo thrombolysis will ultimately require transfer to a PCI-capable facility for elective angiography and PCI as necessary before discharge. PCI should be considered after fibrinolytics if chest pain or ST-segment elevation persists ≥ 60 minutes after initiation of fibrinolytics or if pain and ST-segment elevation recur, but only if PCI can be initiated < 90 minutes after onset of recurrence. If PCI is unavailable, fibrinolytics can be repeated.

Characteristics and selection of fibrinolytic drugs are discussed elsewhere.