Is amlodipine (calcium channel blocker) contraindicated in patients with 2nd degree heart block?

Amlodipine is Contraindicated in Second-Degree Heart Block

Amlodipine is contraindicated in patients with second-degree heart block, particularly Mobitz type II second-degree atrioventricular block, unless the patient has a functioning pacemaker. 1

Rationale for Contraindication

• Calcium channel blockers, including amlodipine, can negatively affect atrioventricular conduction and potentially worsen existing conduction abnormalities 1
• Specifically for second-degree atrioventricular block, calcium channel blockers can reduce atrioventricular conduction and potentially cause a complete atrioventricular block 1
• According to the 2023 clinical guidelines, amlodipine and other calcium channel blockers are explicitly contraindicated in patients with Mobitz type II second-degree atrioventricular block 1

Different Types of Calcium Channel Blockers and Their Effects

• Calcium channel blockers are divided into two main categories:

  • Dihydropyridines (like amlodipine, nifedipine, felodipine) - primarily cause peripheral vasodilation 1
  • Non-dihydropyridines (like verapamil, diltiazem) - have more pronounced negative effects on heart rate and AV conduction 1

• While dihydropyridines like amlodipine have less direct effect on AV conduction than non-dihydropyridines, they are still contraindicated in second-degree heart block 1

Specific Recommendations for Patients with Heart Block

• In patients with second-degree atrioventricular block who need treatment for conditions like angina or hypertension, other antianginal or antihypertensive agents should be preferred 1
• Appropriate alternatives for these patients include:
  • Nitrates 1
  • Ivabradine 1
  • Ranolazine 1
  • Trimetazidine (where available) 1

Special Considerations

• If a patient with second-degree heart block has a functioning pacemaker, amlodipine may be considered, but consultation with a cardiologist is still recommended 1
• For patients with first-degree AV block, careful monitoring is advised if amlodipine is used, as there is potential for progression to higher-degree blocks 1
• Case reports have documented exacerbation of AV block with amlodipine, particularly when combined with other medications that might affect cardiac conduction 2

Clinical Implications

• Before initiating amlodipine therapy in any patient, an electrocardiogram should be performed to determine the presence of any pre-existing cardiac conduction abnormalities 1
• For patients already on amlodipine who develop second-degree heart block, the medication should be discontinued 2
• In patients with coronary artery disease and conduction disorders, alternative antianginal medications that don't affect AV conduction should be considered first-line therapy 1

In conclusion, amlodipine should not be used in patients with second-degree heart block due to the risk of worsening conduction abnormalities and potentially causing complete heart block. This contraindication is clearly stated in current clinical guidelines and supported by the understanding of calcium channel blockers' effects on cardiac conduction.