Should Diltiazem (diltiazem) or Metoprolol (metoprolol) be used to manage atrial flutter with borderline hypertension in a patient?

From the Guidelines

For a patient with borderline blood pressure and atrial flutter with a ventricular rate in the 140s, metoprolol is generally preferred over diltiazem. This recommendation is based on the most recent guidelines, including the 2024 ESC guidelines for the management of atrial fibrillation 1, which suggest that beta-blockers are a first-choice drug for controlling heart rate in patients with atrial fibrillation, and by extension, atrial flutter.

Key Considerations

• Metoprolol offers better hemodynamic stability in patients with borderline blood pressure because it has less direct vasodilatory effect compared to diltiazem, which can cause more significant hypotension 1.
• Beta-blockers like metoprolol provide long-term benefits in atrial flutter by reducing sympathetic tone and potentially preventing recurrence.
• The initial dose of metoprolol can be 5 mg IV slowly over 2-5 minutes, which can be repeated twice at 5-minute intervals if needed (maximum 15 mg), followed by oral metoprolol 25-50 mg twice daily for maintenance.

Alternative Options

• If metoprolol fails to control the rate adequately or causes excessive bradycardia or hypotension, consider adding or switching to low-dose diltiazem (starting at 5-10 mg/hr infusion) with careful blood pressure monitoring 1.
• Diltiazem should be used with caution, especially in patients with advanced heart failure or those with heart block or sinus node dysfunction in the absence of pacemaker therapy, as it can exacerbate these conditions.

Monitoring and Further Management

• Regardless of medication choice, these patients require close monitoring of vital signs, consideration of underlying causes of the atrial flutter, and evaluation for potential cardioversion if rate control alone is insufficient 1.
• The choice between metoprolol and diltiazem should be guided by the patient's specific clinical context, including the presence of any comorbidities that may influence the choice of rate control agent.

From the FDA Drug Label

Although precise mechanisms of its antianginal actions are still being delineated, diltiazem hydrochloride is believed to act in the following ways: • Angina Due to Coronary Artery Spasm: Diltiazem hydrochloride has been shown to be a potent dilator of coronary arteries both epicardial and subendocardial • Exertional Angina: Diltiazem hydrochloride has been shown to produce increases in exercise tolerance, probably due to its ability to reduce myocardial oxygen demand. Like other calcium antagonists, diltiazem decreases sinoatrial and atrioventricular conduction in isolated tissues and has a negative inotropic effect in isolated preparations.

Diltiazem is a calcium channel blocker that can be used to treat atrial flutter and high blood pressure.

• It works by reducing heart rate and lowering blood pressure.
• However, the use of diltiazem in patients with atrial flutter should be done with caution, as it can prolong AV node refractory periods and rarely result in abnormally slow heart rates.
• Metoprolol, a beta-blocker, can also be used to treat high blood pressure and atrial flutter, but its use with diltiazem may result in additive effects on cardiac conduction.
• Given the patient's borderline blood pressure and atrial flutter, diltiazem may be a suitable option, but close monitoring of the patient's heart rate and blood pressure is necessary 2.
• It is also important to consider the potential interactions between diltiazem and other medications, such as beta-blockers, and to exercise caution when using diltiazem in patients with impaired ventricular function 2.

From the Research

Comparison of Diltiazem and Metoprolol for Atrial Flutter

• Diltiazem and metoprolol are both used to treat atrial fibrillation/flutter, but their effectiveness can vary 3.
• A study comparing the two found that diltiazem was more effective in achieving rate control in patients with atrial fibrillation/flutter 3.
• Another study found that intravenous diltiazem was more effective than intravenous metoprolol for heart rate control in randomized trials, but not in observational studies 4.

Safety Outcomes

• A meta-analysis found that metoprolol was associated with a 26% lower risk of adverse events compared to diltiazem 5.
• However, another study found that diltiazem was not associated with a higher risk of hypotension or bradycardia compared to metoprolol 6.
• A retrospective chart review found that neither hypotension nor bradycardia were significantly different between patients treated with diltiazem or metoprolol 7.

Rate Control

• A study found that diltiazem achieved a significantly greater numerical and percent decrease in heart rate at 0.5 hours compared to metoprolol 6.
• Another study found that time to rate control was significantly shorter with diltiazem compared to metoprolol 7.
• However, a study found that there was no difference in sustained rate control between patients treated with diltiazem or metoprolol 7.