Which medication is contraindicated in a patient with heart failure and an EF of 30% due to risk of severe hypotension when combined with nitrates?

Which medication is contraindicated in a patient with heart failure and an EF of 30% due to risk of severe hypotension when combined with nitrates?

• A. Sildenafil
• B. Nitroglycerin
• C. Enalapril
• D. Furosemide

Answer: (A)

The key concept is the dangerous interaction between nitrates and PDE5 inhibitors. Sildenafil, a PDE5 inhibitor used for erectile dysfunction, blocks the breakdown of cGMP in smooth muscle. Nitrates increase nitric oxide, which raises cGMP and causes vasodilation. When both are present, cGMP accumulates too much, leading to severe, potentially life-threatening hypotension. In a patient with heart failure and an ejection fraction of 30%, this drop in blood pressure can dramatically worsen perfusion and decompensation. Therefore sildenafil is contraindicated with nitrates. The other medications listed do not carry this same interaction risk with nitrates; nitroglycerin itself is a nitrate used for symptom relief, while enalapril and furosemide are standard heart-failure therapies without this dangerous nitrate–PDE5 inhibitor synergy.

The key concept is the dangerous interaction between nitrates and PDE5 inhibitors. Sildenafil, a PDE5 inhibitor used for erectile dysfunction, blocks the breakdown of cGMP in smooth muscle. Nitrates increase nitric oxide, which raises cGMP and causes vasodilation. When both are present, cGMP accumulates too much, leading to severe, potentially life-threatening hypotension. In a patient with heart failure and an ejection fraction of 30%, this drop in blood pressure can dramatically worsen perfusion and decompensation. Therefore sildenafil is contraindicated with nitrates.

The other medications listed do not carry this same interaction risk with nitrates; nitroglycerin itself is a nitrate used for symptom relief, while enalapril and furosemide are standard heart-failure therapies without this dangerous nitrate–PDE5 inhibitor synergy.