Percutaneous Coronary Intervention in ACS and ROSC

The treatment of choice for the management of ST-elevation myocardial infarction is coronary angioplasty with or without stent placement. The goal of health care providers in managing patients with this type of acute coronary syndrome (ACS) is to treat within the first hours of the onset of symptoms.¹ Percutaneous coronary intervention (PCI) can restore flow of blood into the myocardium in more than 90% of patients if performed by a skilled provider at a proficient PCI facility with a “door-to-balloon” time of less than 90 minutes.^2-4

Unstable angina and acute non-ST elevation myocardial infarction (NSTEMI) are medical emergency sub-types of acute coronary syndrome. The patients that develop hemodynamic instability, heart failure, persistent angina at rest despite intensive medical therapy, mitral regurgitation, formation of a new ventricular septal defect, or sustained ventricular arrhythmias are at extremely high risk. Either way, both of these types of patients should immediately undergo coronary arteriography and revascularization. Fibrinolysis should be avoided in NSTEMI or unstable angina.^5-7 The choice of revascularization procedure after angiography is dependent on the size and location of the blockage. PCI is most often performed on appropriate lesions, while coronary artery bypass grafting (CABG) is preferred in left main or equivalent disease, such as two or three vessel disease involving the left anterior descending artery with left ventricular dysfunction. On the other hand, 9% to 14% of patients with NSTEMI who undergo angiography have no significant coronary artery disease; these are thought to be caused by rapid clot lysis, vasospasm, myocarditis, and coronary microvascular disease.^8-11 These patients have a much better short-term prognosis than those with a culprit lesion.

Some issues relate to the performance of PCI and these include the development of bare metal stents (BMS), which have surpassed balloon angioplasty in the management of coronary artery disease because one of their ability to prevent restenosis by suppressing arterial recoil and contraction. However, 10% to 20% of patients may still experience restenosis after one year due to excessive growth of a neointima.^12-14 These have been reduced due to the emergence of drug eluting stents (DES), which have the ability to reduce revascularization rates by as much as 70%. For this reason, DES is preferred in the majority of PCI procedures.

In patients undergoing primary PCI, the radial artery approach is preferred over the femoral artery approach (if performed by a skilled operator) because bleeding is a common complication with STEMI.^15-16 Direct stenting is also preferred due to low-profile stent delivery (no need for pre-dilation), less radiation exposure and contrast, and shorter procedural times. In the patient with acute STEMI undergoing primary PCI, direct stenting decreases embolization of plaque constituents, lowers the incidence of no-reflow phenomenon and increases myocardial perfusion and salvage.^17-19 Because of the improvements in PCI, primary PCI with stenting performed in a timely manner is associated with better outcomes than fibrinolysis. However, in centers with no access to prompt PCI, fibrinolytic therapy is indicated.

PCI following return of spontaneous circulation (ROSC) after out-of-hospital cardiac arrest has shown positive results because half of these patients demonstrated acute coronary occlusion.²⁰ Most of the etiology of out-of-hospital cardiac arrest were due to ventricular fibrillation (VF) secondary to ST-elevation myocardial infarction (STEMI) or new left bundle branch block (LBBB). Therefore, angiography with revascularization of the infarct-related artery is recommended in this setting (Class I). The use of PCI in patients with ROSC of presumed ischemic cardiac etiology is reasonable even with an absence of clearly defined STEMI (Class 2B). More randomized controlled trials are needed to further validate these findings. Cardiac angiography and PCI, when integrated into a standardized post-cardiac arrest protocol, improves survival to hospital discharge.²¹ This is also due to the fact that successful PCI improves the cardiac ejection fraction.²⁰ Survival in post-cardiac arrest patients with STEMI is as high as 70% to almost 100%, depending on how fast a PCI is performed following a witnessed arrest due to VF.^22-23 Primary PCI has also shown to be applicable in NSTEMI because early revasculariztion in this setting has resulted in hemodynamic and electrical stability.

Lastly, it is common for patients to remain comatose after out-of-hospital cardiac arrest. After ROSC, a comatose state is not a contraindication to perform angiography and PCI in these patients. The goal of PCI in these patients is to keep neurological function intact to increase survival.

PCI can prevent the evolution of myocardial necrosis, prevent major adverse cardiac events (MACE), and treat the complications of ACS such as ventricular fibrillation, pulseless ventricular tachycardia, unstable tachycardias, symptomatic bradycardias, pulmonary edema, cardiogenic shock and mechanical complications of acute myocardial infarction. It is essential that hospitals be equipped with systems to provide prompt and effective PCI to increase survival to hospital discharge in post-cardiac arrest victims.

Sources

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• Magid DJ, Calogne BN, Rumsfeld JS, Canto JG, Frederick PD, et. al. Relation between hospital primary angioplasty volume and mortality for patients with acute MI treated with primary angioplasty vs. thrombolytic therapy, JAMA. 2000:284:3131-3138.
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• Dalby M, Bouzamondo A, Lechat P, Montalescot G. Transfer for primary angioplasty versus immediate thrombolysis in acute myocardial infarction: a meta-analysis. Circulation. 2003;108:1809-1814.
• Harrington RA, Becker RC, Cannon CP, et.al. Antithrombotic therapy for non-ST-segment elevation acute coronary syndromes: American College of Chest Physicians Evidence-Based Clinical Practice Guidelines (8^th edition). Chest 2008;133:670S
• Effects of tissue plasminogen activator and a comparison of early invasive and conservative strategies in unstable angina and non-Q-wave myocardial infarction. Results of the TIMI IIIB Trial. Thrombolysis in Myocardial Ischemia. Circulation 1994; 89:1545.
• Anderson HV, Canon CP, Stone PH, et al. One-year results of the thrombolysis in myocardial infarction (TIMI) IIIB clinical trial. A randomized comparison of tissue-type plasminogen activator versus placebo and early invasive versus early conservative strategies in unstable angina and non-Q wave myocardial infarction. J Am Coll Cardiol 1995; 26:1643.
• Canon CP, Weintraub WS, Demopoulos LA, et. al. Comparison of early invasive and conservative strategies in patients with unstable coronary syndromes treated with glycoprotein IIb/IIIa inhibitor tirofiban. N Engl J Med 2001; 344: 1879.
• Bugiardini R, Manfrini O, De Ferrari GM. Unanswered questions for management of acute coronary syndrome: risk stratification of patients with minimal disease or normal findings on coronary angiography. Arch Intern Med 2006; 166:1391.
• Diver DJ, Bier JD, Ferreira PE, et. al. Clinical and arteriographic characterization of patients with unstable angina without critical coronary arterial narrowing (from the TIMI-IIIA Trial). Am J Cardiol 1994; 74:531.
• Roe MT, Harrington RA, Prosper DM, et. al. Clinical and therapeutic profile of patients presenting with acute coronary syndromes who do not have significant coronary artery disease. The Platelet Glycoprotein IIb/IIIa in Unstable Angina: Receptor Suppression Using Intergrilin Therapy (PURSUIT) Trial Investigators. Circulation 2000; 102:1101
• Fischman, DL, Leon MB, Baim DS, et. al. A randomized comparison of coronary stent placement and balloon angioplasty in the treatment of coronary artery disease. Stent Restenosis Study Investigators. N Engl J Med 1994; 331:496.
• Serruys PW, de Jaegere P, Kiemmeneij F, et al. A comparison of balloon-expandable-stent implantation with balloon angioplasty in patients with coronary artery disease. Benestent Study Group. N Engl J Med 1994; 331-489.
• Cutlip DE, Chauhan MS, Baim DS, et al. Clinical restenosis after coronary stenting: perspectives from multicenter clinical trials. J Am Coll Cardiol 2002; 40:2082.
• Hamon M, Rassmussen LH, Manoukian SV, et. al. Choice of arterial access site and outcomes in patients with acute coronary syndromes managed with an early invasive strategy: the ACUITY trial. Euro Intervention 2009; 5:115.
• Cantor WJ, Puley G, Natarajan MK, et. al. Radial versus femoral access for emergent percutaneous coronary intervention with adjunct glycoprotein IIb/IIIa inhibition in acute myocardial infarction – the RADIAL-AMI pilot randomized trial. Am Heart J 2005; 150:543.
• Loubeyre C, Morice MC, Lefevre T, et al. A randomized comparison of direct stenting with conventional stent implantation in selected patients with acute myocardial infarction. J Am Coll Cardiol 2002; 39:15.
• Ly HQ, Kirtane AJ, Buros J, et. al. Angiographic and clinical outcomes associated with direct versus conventional stenting among patients treated with fibrinolytic therapy for ST-elevation acute myocardial infarction. Am J Cardiol 2005; 95:383.
• Antoniucci D, Valenti R, Migliorini A, et al. Direct infarct artery stenting without predilation and no-reflow in patients with acute myocardial infarction. Am Heart J 2001; 142:684.
• Spaulding CM, Joly LM, Rosbenberg A, Monchi M, et al. Immediate coronary angiography in survivors of out-of hospital cardiac arrest. N Engl J Med. 1997;336:1629-1633.
• Sunde K, Pytte M, Jacobsen D, Mangschau A, Jensen LP, et. al. Implementation of a standardized treatment protocol for post resuscitation care after out-of-hospital cardiac arrest. Resuscitation. 2007:73:29-39.
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