Which hemodynamic parameter is primarily reduced by the combination of furosemide and nitroglycerin in a patient with STEMI and signs of heart failure?

• A. Afterload only
• B. Preload
• C. Myocardial contractility
• D. Heart rate alone

Answer: (B)

Preload is the main concept here. In heart failure with STEMI, easing the heart’s filling pressures helps reduce pulmonary congestion and the work the ventricle must do. Furosemide promotes diuresis, which lowers the circulating fluid volume and venous return, thereby reducing the left ventricular end-diastolic pressure. Nitroglycerin cause venodilation, which also decreases venous return and LV filling pressures. Together, these actions primarily lower preload, relieving congestion and wall stress on a failing ventricle. They do not primarily increase contractility, and while nitroglycerin can modestly lower afterload, the dominant effect of this combination in this setting is preload reduction.