Mechanical Reperfusion

Coronary angioplasty is the most common percutaneous intervention. Alternatives include coronary stent placement, atherectomy, and laser angioplasty. Balloon angioplasty increases the size of the arterial lumen through endothelial denudation; cracking, splitting, and disruption of atherosclerotic plaque; dehiscence of intima and plaque from underlying media; and stretching or tearing of underlying media and adventitia. 10 With successful dilation, small amounts of arterial wall dissection and aneurysmal expansion may be seen. The greater the increase in luminal size, the lower is the risk of restenosis. On the other hand, more aggressive balloon inflation can be associated with excessive dissection, platelet deposition, thrombus formation, and plaque hemorrhage. 10

Alternative percutaneous interventional procedures have been developed in an attempt to limit complications. Directional and rotational coronary atherectomy extract atherosclerotic tissue from the coronary artery. Excimer laser atherectomy vaporizes atheromatous tissue. Their use results in larger luminal diameters but has not reduced rates of restenosis or other complications associated with percutaneous angioplasty procedures.

Coronary stents are fenestrated stainless-steel tubes that are expanded by a balloon to provide scaffolding within the coronary arteries. The addition of antiplatelet therapies (in particular, glycoprotein IIb/IIIa inhibitors) has been associated with reduced rates of abrupt vessel closure and improved outcomes up to 3 years following the procedure.

Direct coronary angioplasty has compared favorably with fibrinolytic therapy for the treatment of patients with AMI. In centers with significant expertise in direct angioplasty, primary angioplasty reduces the cardiovascular complication rate in patients with AMI relative to fibrinolytic therapy. The PAMI trial compared the efficacy of intravenous tPA with immediate percutaneous coronary angioplasty (PTCA) in 395 patients with AMI. The in-hospital mortality rate in the tPA group was 6.5 percent and in the PTCA group was 2.6 percent. In-hospital reinfarction rates, 6-month rates of reinfarction or death, and rates of intracranial hemorrhage were all lower in the PTCA group.11 In GUSTO IIb, 1138 patients who presented within 12 h of AMI were randomized to accelerated tPA or to primary angioplasty. The incidence of death, nonfatal reinfarction, and nonfatal disabling stroke was 33 percent lower in patients who received primary angioplasty. 12 A large study of patients presenting to community hospitals did not show a benefit of direct angioplasty over fibrinolysis. 13

Primary angioplasty may offer benefits in highly specialized centers with ready availability of cardiac catheterization and skilled operators that are not apparent with longer delays or less skilled operators. The decision to use primary interventional procedures rather than fibrinolysis should be individualized based on the institutional expertise and availability and risk of complications from fibrinolysis.

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