From the Guidelines
Beta-blockers and non-dihydropyridine calcium channel blockers should be avoided in patients with second-degree heart block due to their potential to worsen the condition by further slowing conduction through the AV node. During second-degree heart block, it is crucial to avoid medications that can exacerbate the condition. Beta-blockers, such as metoprolol, atenolol, propranolol, and carvedilol, and non-dihydropyridine calcium channel blockers, such as diltiazem and verapamil, can slow heart rate and reduce conduction through the cardiac electrical system, which is already compromised in second-degree heart block 1. These medications can potentially progress the heart block to a more severe degree.
Alternatives for Blood Pressure Control
If blood pressure control is needed, safer alternatives include:
- Dihydropyridine calcium channel blockers, such as amlodipine and nifedipine
- ACE inhibitors, such as lisinopril and enalapril
- ARBs, such as losartan and valsartan
- Diuretics, such as hydrochlorothiazide and furosemide Patients with second-degree heart block should be monitored closely, and some may require pacemaker implantation if the block is symptomatic or at risk of progressing to complete heart block 2. It is essential to prioritize the patient's safety and avoid medications that can worsen their condition, as recommended by the expert consensus document 1.
From the FDA Drug Label
Atrioventricular block: The effect of verapamil on AV conduction and the SA node may cause asymptomatic first-degree AV block and transient bradycardia, sometimes accompanied by nodal escape rhythms. PR-interval prolongation is correlated with verapamil plasma concentrations, especially during the early titration phase of therapy. Higher degrees of AV block, however, were infrequently (0. 8%) observed. Marked first-degree block or progressive development to second- or third-degree AV block, requires a reduction in dosage or, in rare instances, discontinuation of verapamil hydrochloride and institution of appropriate therapy, depending upon the clinical situation
Verapamil should be avoided or used with caution in patients with second-degree heart block due to its potential to cause higher degrees of AV block. The clinical decision should be made based on the individual patient's condition and the potential risks and benefits of verapamil therapy 3.
From the Research
Blood Pressure Medications to Avoid in Second-Degree Heart Block
- Beta blockers and slow channel blockers, such as diltiazem and verapamil, can affect atrioventricular (AV) nodal function and may worsen heart block 4.
- These medications can prolong AV nodal conduction and refractoriness, potentially leading to second-degree AV block, although this is rare in patients receiving maintenance therapy 4.
- In patients with abnormal AV conduction, the effect of slow channel blockers and beta blockers on the AV node can be more pronounced, increasing the risk of heart block 4.
- Non-dihydropyridine calcium channel blockers (NDCC), such as diltiazem and verapamil, are generally avoided in patients with heart failure with reduced ejection fraction, but their use in second-degree heart block is not explicitly contraindicated 5.
- Beta blockers are recommended to be used with caution in patients with second-degree heart block, as they can further depress AV nodal function and worsen heart block 5.
Alternative Treatment Options
- Diuretics and calcium-blocking drugs, such as dihydropyridine calcium channel blockers, may be alternative treatment options for hypertension in patients with second-degree heart block, as they have been shown to be effective in lowering blood pressure with fewer side effects 6, 7.
- Angiotensin-converting enzyme (ACE) inhibitors and angiotensin receptor blockers (ARBs) may also be considered, although their effectiveness in combination with diuretics or beta-blockers may vary 6.