Moderate
Established
Deskripsi
Diltiazem combined with metoprolol increases the risk of bradycardia and AV block through additive negative chronotropic and dromotropic effects.
Mekanisme
Diltiazem inhibits L-type calcium channels in SA and AV nodes, slowing conduction; metoprolol's beta-1 blockade also slows AV nodal conduction. The effects are additive.
Signifikansi Klinis
Symptomatic bradycardia and AV block have been documented; less severe than verapamil + beta-blocker but still clinically significant.
Penatalaksanaan
Monitor heart rate and ECG; start at low doses; avoid combination in patients with pre-existing conduction system disease or sinus node dysfunction.