In reality, this patient was not emergently reperfused, his troponin ended up peaking at 76 ng/ml, and he was found to have subtotal OM occlusion.
36 Answers 14. B. The patient would have best been treated with early coronary angiography and PCI at 3–24 hours after thrombolysis. Beyond 24 hours, coronary angiography may still be performed (class IIa), even in the absence of recurrent pain or persistent HF (the patient only had transient HF on admission). However, stress testing has a higher recommendation in the ACC guidelines (ESC gives equal weight to both). Exercise testing is preferred as the patient is able to ambulate.
37 Answers 15. D. In the first 3 hours of STEMI, especially the first hour, and in the absence of shock, the mortality reduction with thrombolysis is likely equivalent to that of primary PCI, provided that rescue PCI is performed if needed (CAPTIM, PRAGUE [<3 hours subgroup], STREAM trials). If thrombolysis is used as a primary revascularization strategy, outcomes are improved when thrombolysis is followed by routine early PCI (further reduction of recurrent MI in comparison to thrombolysis alone).
38 Answers 16. E. Both new LBBB and RBBB are associated with a similarly increased mortality. A transient LBBB or RBBB is not associated with increased mortality.
39 Answers 17. D.
40 Answers 18. C. The patient is in shock, which is aggravated by the inappropriate heart rate. In shock, compensatory tachycardia is expected, but the 2:1 AV block is cutting the patient’s ventricular rate in half. In the first 24 hours of inferior MI, AV block is responsive to atropine. In the context of inferior MI, hypotension with clear lungs suggests hypovolemia or RV shock, so fluid administration is appropriate. Those simple measures are performed while PCI is being arranged.
41 Answers 19. A. The patient has shock with clear lungs and no hypoxia, which suggests RV shock. Inferior MI does not usually lead to LV shock, unless a mechanical complication occurs or the inferior MI is associated with posterolateral extension or an old anterior MI. The exam does not suggest LV failure or mechanical complication.
42 Answers 20. F. The most definitive therapy of RV shock is primary PCI. Simultaneously, IV fluids are administered. In acute RV failure, the RV is small and non-compliant, in a way that JVP of 10-14 mmHg (13-18 cmH2O) was associated with the best stroke volume in one study. Stroke volume universally declined when RA pressure exceeded 14 mmHg. If JVP is elevated and the patient is unresponsive to a fluid challenge, norepinephrine therapy is appropriate (preferred to dopamine). In RV shock, IABP is warranted if high-dose pressors are required despite reperfusion or if LV failure is concomitantly present.
43 Answers 21. B. Clinically, the patient does not appear to have pulmonary edema. His hypoxemia is likely due to an underlying, previously innocent PFO. With RV failure and fluid resuscitation, the RA pressure rises and causes exaggerated flow through the PFO and a right-to-left shunt with hypoxemia refractory to O2.
44 Answers 22. G. The patient’s nausea represents the true onset of MI (angina-equivalent). Her shock 2 days later is due to a papillary muscle rupture. It is likely that the anterior papillary muscle is ruptured in this patient with non-inferior MI (likely LCx-related MI). The anterior papillary muscle is supplied by both the LCx and the LAD (usually first diagonal); an LCx-related MI may lead to papillary muscle rupture if the LAD also has an underlying stenosis. The infarct associated with papillary muscle rupture may be small, as in this case. The wide pulse pressure and the fever suggest an associated vasodilatory or septic shock, which is seen in 25% of post-MI cardiogenic shock. In this patient, echo is subsequently performed and shows rupture of the anterolateral papillary muscle (echodense mass attached to the leaflets) with flailing of both leaflets and both a central and a posterior jet. SVR is low (~600–700) and cardiac index relatively high, despite MR (~4 l/min/m2), confirming an associated vasodilatory/septic shock.
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