C. Preoperative coronary arteriography
E. Spironolactone

 

C. Preoperative coronary arteriography

E. Spironolactone

 

Answer

The correct answer is E. This patient is at moderate risk for an ischemic event, given his limited functional capacity, hypertension, diabetes, age, and history of left bundle branch block. However, his functional capacity is at least 4 metabolic equivalent by the Duke Criteria. If the surgery were not emergent, further evaluation would have been helpful to delineate his cardiac function. However, since he is not having active ischemia, his cardiac status should be optimized with a beta-blocker, which has been shown to reduce perioperative mortality.
Canceling the surgery (choice A) would not be appropriate, given the patient's presentation and the lack of any absolute contraindication to surgery.
Clearance for surgery (choice B) without optimization with a beta-blocker is not optimal either because the patient does have significant cardiac risk factors.
Coronary arteriography (choice C) can be explored after surgery. It is not an option preoperatively: even if the patient does need stenting, it is not possible to do so because he cannot be placed on anticoagulation after the procedure.
Stress testing (choice D) would not change the patient's management inasmuch as he is not actively ischemic; he will be placed on beta-blockers in any case, and he cannot undergo angioplasty or stenting.

2.
The correct answer is E. Spironolactone, a mineralocorticoid antagonist, is proven to reduce morbidity and mortality in congestive heart failure. Aldosterone was originally thought to be important int he pathophysiology of the heart failure only because of its ability to increase sodium retention and potassium loss. However, in the past several years, research has shown that aldosterone also causes myocardial and vascular fibrosis, direct vascular damage, and baroreceptor dysfunction and prevents the uptake of norepinephrine by myocardium. The reduction in the risk of death does not appear to be due entirely to an effect of spironolactone on sodium retention or potassium loss; instead, it is likely that spironolactone is also cardioprotective. Although the exact cause
of the reduction in the risk of death remains speculative, it is postulated that an aldosterone-receptor blocker can prevent progressive heart failure by averting sodium retention and myocardial fibrosis and preventing sudden death from cardiac causes by averting potassium loss and by increasing the myocardial uptake of norepinephrine. Spironolactone may prevent myocardial fibrosis by blocking the effects of aldosterone on the formation of collagen, which in turn could play in reducing the risk of sudden death from cardiac causes, since myocardial fibrosis could predispose patients to variations in ventricular-conduction times and, hence, to reentry ventricular arrhythmias.
Acetazolamide (choice A) is a weak diuretic that acts by inhibiting luminal carbonic anhydrase in the renal tubules. It is often used to alkalinize the urine, trapping acidic toxins in the urine that would otherwise diffuse back across the luminal membrane. Its role in CHF is limited.
Ethacrynic acid (choice B) is a loop diuretic used instead of furosemide in patients with sulfa allergies.
Furosemide (choice C) is usually the drug of choice in maintaining a balanced fluid status in CHF patients. It has no proven benefit on long-term mortality, however, and does not influence the natural course of the disease.
Thiazide diuretics, such as hydrochlorothiazide (choice D) or metolazone, are sometimes used synergistically with a loop diuretic in patients with severe edema. This combination may reduce symptoms, but is not proven to reduce mortality.