Which class of calcium channel blockers may be harmful due to negative inotropic effects?

Which class of calcium channel blockers may be harmful due to negative inotropic effects?

• A. Dihydropyridine CCBs (e.g., amlodipine)
• B. Nondihydropyridine CCBs (verapamil and diltiazem)
• C. Beta-blockers
• D. ACE inhibitors

Answer: (B)

Nondihydropyridine calcium channel blockers are the class with notable negative inotropy. Verapamil and diltiazem block L-type calcium channels in cardiac myocytes and the AV node, which reduces calcium influx during systole. Less calcium means weaker heart muscle contractions, so these drugs can depress contractility and slow conduction. This makes them potentially harmful in patients with impaired left ventricular function or decompensated heart failure. Dihydropyridine calcium channel blockers, like amlodipine, mainly cause vascular smooth muscle relaxation with less direct effect on myocardial contractility (though they can cause reflex tachycardia). Beta-blockers and ACE inhibitors are not calcium channel blockers, so they don’t share this negative-inotropy mechanism.

Nondihydropyridine calcium channel blockers are the class with notable negative inotropy. Verapamil and diltiazem block L-type calcium channels in cardiac myocytes and the AV node, which reduces calcium influx during systole. Less calcium means weaker heart muscle contractions, so these drugs can depress contractility and slow conduction. This makes them potentially harmful in patients with impaired left ventricular function or decompensated heart failure.

Dihydropyridine calcium channel blockers, like amlodipine, mainly cause vascular smooth muscle relaxation with less direct effect on myocardial contractility (though they can cause reflex tachycardia). Beta-blockers and ACE inhibitors are not calcium channel blockers, so they don’t share this negative-inotropy mechanism.