Chapter 21 Marini Acute Coronary Syndromes

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SECTION II • Medical and Surgical Crises

about 0.5% to 1.5% experience an IC bleed. Factors that predict risk of major bleeding are advanced age (>70 years), female gender, low body weight, hypertension at presentation, bleeding diathesis, IC neoplasms, and previ- ous stroke. Fibrin-specific agents are more prone to cause bleeding than SK. IC bleeds are heralded by mental obtundation, focal CNS deficits, and intense headaches. With onset of these symptoms, one must stop the fibrinolytic therapy, heparin, and all antiplatelet agents including aspirin. A stat CT scan of the head will help confirm the diagnosis. The treatment consists of packed red blood cell transfusions (if hematocrit drops below 25% and there is associated hypotension), cryoprecipitate infu- sion (approx. 10 units), and fresh frozen plasma infusion if there is continued bleeding (2 to 6 units). Intravenous protamine (25 to 50 mg after a small test dose) may be needed to reverse the effect of heparin. Platelet transfu- sions (6 to 12 units) may be needed for con- tinued bleeding, especially if the patient has received abciximab, clopidogrel, and aspirin. Patients with thrombocytopenia (<100,000/ mm 3 ) have an 8- to 10-fold risk of bleeding with fibrinolytic therapy. 2. Anaphylaxis: Encountered rarely, primarily with SK. Prompt recognition, stopping the drug, airway maintenance, intravenous epinephrine (1 to 5 cc of 1:10,000 solution), intravenous fluid boluses, intravenous hydrocortisone, and methylprednisone are the cornerstones of ther- apy. Less commonly, intravenous dopamine, phenylephrine, or norepinephrine infusion and inhaled albuterol aerosol may be necessary for persistent hypotension. 3. Hypotension: Occurs in 10% to 15% patients with SK. Slowing the infusion rate and giv- ing intravenous fluids usually suffices, but occasionally the drug infusion may have to be stopped temporarily until the blood pressure improves. 4. ReperfusionArrhythmias: The usual reperfu- sion arrhythmias seen with fibrinolytic therapy are runs of idioventricular rhythm (IVR) (rate 90 to 120 beats/min) and VT. These rhythm disturbances are usually transient and do not need treatment other than β -blocker therapy. VF can also occur occasionally with reperfusion

and this usually responds promptly to defibrilla- tion. With inferior wall MI from dominant RCA occlusion, one may see transient, third-degree AV block with reperfusion. 5. Miscellaneous: Fever, skin rash, and rigors. All these are more common with SK. Skin rash necessitates stopping infusion and considering t-PA or PCI. Benadryl and hydrocortisone given by intravenous route seem to help. Primary Percutaneous Coronary Intervention (PCI—PTCA and Stenting) • Primary PCI of the infarct-causing vessel is today the preferred method of reperfusion in patients with STEMI. Mechanical reperfusion with PTCA and stenting has been shown to be superior to fibrinolytic therapy. When performed soon enough, PTCA achieves TIMI-3 flow in the infarct-related vessel in approximately 90%, compared to 50% to 60% TIMI-3 flow rates with the best fibrinolytic regimen. • The improved rate of establishing infarct vessel patency with PCI has translated into better clini- cal outcomes, compared to fibrinolytic therapy. In meta-analyses of trials comparing primary PTCA to fibrinolytic therapy, there has been reported 30% to 50% reduction of death, reinfarctions, and stroke at 1 and 6 months. Improvement in rates of stroke and reinfarction is responsible for most of the benefit seen with PCI. PCI has been shown to save 21 more lives than fibrinolytic therapy for every 1,000 patients treated. • Although “sooner the better” definitely applies, PCI in STEMI is not quite as time-dependent as fibrinolytic therapy. Primary PTCA reduced 30-day rates of major cardiac events (death, rein- farction, CVA) by 54% in patients presenting within 2 hours of onset of symptoms, 39% for those presenting within 2 to 4 hours of symptom onset, and 21% for those presenting after 4 hours. This is not the case with fibrinolytic therapy, where the benefit diminishes exponentially with each passing hour after onset of symptoms. • The risk of intracerebral hemorrhage is about 0.1% with primary PCI, which therefore is par- ticularly a good option for those beyond 70 years of age, in whom fibrinolytic therapy significantly increases the risk of bleeding. It is the only defin- itive treatment that can be offered in those with absolute contraindications to fibrinolysis.