Cardiovascular Drugs USMLE Step 1 Practice Question
A 73-year-old man with a history of coronary artery disease and preserved left ventricular ejection fraction (55%) presents to the emergency department with acute substernal chest pain radiating to his left arm for 30 minutes. Vital signs on arrival are BP 148/88 mmHg, HR 98 bpm, RR 16, and temperature 37.0°C. Physical examination reveals diaphoresis and anxiety. The initial 12-lead ECG shows no acute ST changes. He is given immediate-release sublingual nifedipine for presumed angina. Within 5 minutes, his blood pressure decreases to 105/62 mmHg and heart rate increases to 115 bpm. The patient reports facial flushing but states his chest pain has worsened in severity. Troponin I is negative at presentation and at 3 hours. The patient denies taking any beta-blockers. Which of the following best explains the paradoxical worsening of angina despite blood pressure reduction?
Answer choices
- AReflex sympathetic activation increasing myocardial oxygen demand without concurrent beta-blockadeCorrect answer
- BReduced aortic diastolic pressure leading to decreased coronary perfusion pressure
- CDirect negative inotropic effect of nifedipine causing cardiogenic shock
- DCoronary steal syndrome redirecting blood flow from stenotic to non-stenotic vessels
- EDrug-induced thrombotic occlusion of the coronary artery
- FShortening of diastolic perfusion time due to excessive tachycardia
See the full explanation
Get the correct-answer rationale, why each distractor is wrong, the underlying mechanism, and high-yield associations — plus adaptive practice that targets your weak areas — with a free MedBoardPRO account.