Final answer:
Verapamil (Calan, Verelan) could potentially worsen JF's heart failure condition due to its negative inotropic effects.
Step-by-step explanation:
JF has systolic heart failure with an ejection fraction of 33%. Of the medications listed, Verapamil (Calan, Verelan) could potentially worsen his heart failure condition. Verapamil belongs to the class of calcium channel blockers and it has negative inotropic effects, meaning it decreases the strength of cardiac muscle contractions. This can further weaken the heart's ability to pump blood effectively, worsening the symptoms of heart failure.