Is Diltiazem (Dilt) preferred over Amlodipine for treating vasospastic angina?

Diltiazem and Amlodipine Are Equally Effective for Vasospastic Angina

All calcium channel blockers are recommended for vasospastic angina, with no clear preference between diltiazem and amlodipine—both are equally effective and the choice depends on patient-specific factors such as heart rate, blood pressure, and cardiac conduction status. 1

Guideline Recommendations

Class I Indication for All CCBs in Vasospastic Angina

• Calcium channel blockers are recommended (Class I) for patients with vasospastic angina, with all subclasses causing similar coronary vasodilation. 1

• Long-acting CCBs and nitrates are recommended (Class I) in patients with coronary artery spasm. 1

• All calcium-channel blockers are effective alone or in combination with nitrates in the treatment of vasospastic angina, with similar antianginal efficacy across all agents. 1

Pharmacological Differences That Guide Selection

Diltiazem (Non-Dihydropyridine)

• Diltiazem has less peripheral vasodilatory effect compared to dihydropyridines but produces significant negative chronotropic (heart rate lowering) and dromotropic (AV conduction slowing) effects. 1

• Diltiazem is preferred when heart rate control is needed or in patients with supraventricular tachyarrhythmias, as it directly affects cardiac pacemaker and AV conduction cells. 1

• Diltiazem should be avoided in patients with PR interval >0.24 seconds, second- or third-degree AV block without a pacemaker, or significant LV dysfunction. 1

Amlodipine (Dihydropyridine)

• Amlodipine produces the most marked peripheral arterial vasodilation with minimal direct effects on heart rate, contractility, or AV conduction. 1

• Amlodipine has a gradual onset and long elimination half-life, providing smooth 24-hour coverage with once-daily dosing and lower incidence of reflex tachycardia compared to short-acting dihydropyridines. 2, 3

• Amlodipine is effective in vasospastic angina, significantly reducing anginal episodes (p=0.009) and nitroglycerin consumption in randomized controlled trials. 4

• Amlodipine is preferred when concurrent sildenafil therapy is needed, as dihydropyridines carry lower risk of symptomatic hypotension and bradycardia compared to non-dihydropyridines. 5

Clinical Decision Algorithm

Choose Diltiazem When:

• Patient has elevated heart rate (>70-80 bpm) requiring rate control 1
• Patient has concurrent supraventricular arrhythmias or atrial fibrillation 6
• Patient has hypertrophic cardiomyopathy 1
• Normal cardiac conduction (PR <0.24 seconds) and preserved LV function 1

Choose Amlodipine When:

• Patient has bradycardia or conduction abnormalities (PR >0.24 seconds, AV block) 1
• Patient requires concurrent phosphodiesterase-5 inhibitor therapy (sildenafil, tadalafil) 5
• Patient has LV dysfunction or heart failure, as amlodipine is better tolerated than non-dihydropyridines 1
• Patient experienced excessive bradycardia or AV block with diltiazem 7

Important Caveats

Avoid These Combinations:

• Never use immediate-release nifedipine without beta-blocker therapy (Class III: Harm), as it increases mortality in ACS patients. 1

• Do not combine diltiazem with ivabradine, as both are metabolized by CYP3A4 and cause severe bradycardia risk. 1

Common Adverse Effects:

• Diltiazem may cause AV block and recurrent angina in early weeks of treatment, with efficacy improving by week 12. 7, 6

• Amlodipine commonly causes peripheral edema, headache, dizziness, and flushing due to marked peripheral vasodilation, though these are generally well-tolerated. 2, 3, 4

• Both agents can cause hypotension—monitor blood pressure closely, especially in elderly patients or those with pre-existing cardiovascular disease. 1, 5

Efficacy Evidence

• A 2023 systematic review found both diltiazem and amlodipine potent in decreasing vasospastic angina, with diltiazem showing benefit through 12 weeks and amlodipine reducing VSA by 17-33% after 6 weeks. 7

• Slow-release preparations of both CCBs increase efficacy and compliance compared to immediate-release formulations. 7

• Comparative studies show similar anti-anginal efficacy between amlodipine and diltiazem in chronic stable angina and vasospastic angina. 2, 3