Chapter 21 Marini Acute Coronary Syndromes

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SECTION II • Medical and Surgical Crises

• Role of thrombus aspiration: Thrombus aspiration with an aspiration catheter from the occluded vessel prior to balloon PTCA or stent- ing had been long felt to improve TIMI-3 flow, myocardial blushing, and myocardial salvage. Myocardial blushing on contrast angiography is perhaps a better indicator of clinical outcomes like resolution of ST elevation on ECG and myocardial salvage than angiographic TIMI flow rates. Myocardial blush grade 0 to 1, no or very lit- tle blush; 2, moderate blush; and 3, normal blush indicate no or minimal, moderately reduced, and normal myocardial perfusion, respectively. The TAPAS trial, which randomized more than 1,000 patients with STEMI, compared efficacy of standard practice of balloon angioplasty plus stenting to thrombus aspiration plus stenting, in terms of improvement in myocardial blush- ing. Thrombus aspiration followed by stenting was superior to standard practice of PTCA and stenting in improving myocardial perfusion. This is mainly because thrombus aspiration reduces the risk of the clot breaking loose to occlude the distal coronary microcirculation. Although the 30-day event rate (death and nonfatal MI) was statistically no different between the two groups, the 1-year follow-up data showed a clinical trend that favored thrombus aspiration. • Door-to-balloon (or device) times and pre- hospital cardiac cath-lab activation: The standard recommendation for door-to-balloon time in STEMI patients is less than 90 minutes for both direct admits and for patients being transferred for PCI (door time = time of ini- tial patient arrival in the ER; balloon or device time = time of first balloon inflation or device use [like clot aspiration]). Some cardiac hospitals have developed protocols where the paramedics activate the cath lab from the field after perform- ing a prehospital ECG. The patient is usually brought in directly to the cath lab bypassing the emergency room, thereby reducing delays. This system has helped reduce door-to-balloon times significantly at these institutions. However, there are times when patients with NSTEMI (and/or LVH, pericarditis, early repolarization, etc.) end up arriving in the cath lab inappropriately. The AMI protocol has also been refined significantly in many of the emergency rooms through joint collaboration between the emergency room phy- sicians and the cardiologists. The usual rule is

to get the first ECG within 10 minutes of first encountering a patient with chest pain. Having an AMI protocol streamlines care and reduces delays significantly. The on-call cath-lab team including the interventional cardiologist should be living within 15 to 20 minutes of the hospital. Most often, the patient gets a chest X-ray and, after an aortic dissection is ruled out, gets started on heparin and a Gp2b/3a receptor antagonist, before the cath-lab team takes the patient to the cath lab for PCI. • Facilitated PCI: In small, nonrandomized single-institution studies, there appeared to be some benefit from use of half-dose preproce- dural lytic therapy in patients being transferred for PCI. There were early reports of improved TIMI-3 flow with this strategy. However, a large randomized trial (FINESSE) looking into this matter failed to show any benefit with half-dose lytic therapy prior to angioplasty. Therefore, pre- procedural lytics are no longer recommended. • Rescue PCI: Patients who fail to achieve reper- fusion with fibrinolytic therapy should be trans- ferred to a hospital for emergent PCI. The results of rescue PCI have improved over the last decades with the increased use of intracoronary stents and Gp2b/3a receptor antagonists during PCI. Persis- tent ST elevation and chest pain 90 minutes after administration of fibrinolytic agent and hemody- namic instability therefore signal the wisdom of emergency angiography and rescue PCI. • Immediate or adjunctive PCI: Coronary angiography and PCI that is performed routinely within hours or days after successful reperfusion with fibrinolytics are called immediate or adjunc- tive PCI. After successful fibrinolysis, there usu- ally is a significant residual plaque in the infarct- related vessel that potentially can cause recurrent ischemia or reinfarction. Multiple clinical trials support adjunctive PCI performed routinely after fibrinolytic therapy. There are, however, certain specific indications for postfibrinolytic cardiac catheterization and revascularization: (1) previous history of MI, CAD, PCI, or bypass surgery; (2) LV dysfunction with LVEF less than or equal to 40%; (3) recurrent ischemia (either spontaneous or by stress testing); (4) ventricular tachyarrhythmias with hemodynamic instability; and (5) VT after the first 48 hours of reperfusion. • Delayed PCI: Delayed PCI several days after fibrinolysis is fully justified for recurrent