From the Guidelines
Bradycardia in postmenopausal women is most commonly caused by age-related changes to the cardiac conduction system, medication side effects, hypothyroidism, electrolyte imbalances, and underlying heart disease, as stated in the 2018 ACC/AHA/HRS guideline on the evaluation and management of patients with bradycardia and cardiac conduction delay 1.
Causes of Bradycardia
The causes of bradycardia in postmenopausal women can be diverse, including:
- Age-related changes to the cardiac conduction system, such as sinus node dysfunction or heart blocks, which can lead to persistent sinus bradycardia and chronotropic incompetence without identifiable causes, as described in the 2012 ACCF/AHA/HRS focused update incorporated into the ACCF/AHA/HRS 2008 guidelines for device-based therapy of cardiac rhythm abnormalities 1.
- Medication side effects, particularly from beta-blockers (metoprolol, atenolol), calcium channel blockers (diltiazem, verapamil), digoxin, and certain antiarrhythmics, which can cause bradyarrhythmias, as mentioned in the 2015 ESC guidelines for the management of patients with ventricular arrhythmias and the prevention of sudden cardiac death 1.
- Hypothyroidism, which can slow heart rate due to decreased metabolic demands, and is often associated with the so-called ‘mosque sign’, a dome-shaped symmetric T wave in the absence of a ST segment, as noted in the guidelines for the interpretation of the neonatal electrocardiogram 1.
- Electrolyte abnormalities, particularly hyperkalemia or hypomagnesemia, which may disrupt normal cardiac conduction.
- Underlying heart disease, such as coronary artery disease and other structural heart conditions, which become more common after menopause due to the loss of estrogen's cardioprotective effects.
Management
Management of bradycardia in postmenopausal women depends on the underlying cause and may include:
- Medication adjustments, such as discontinuing or modifying medications that may be contributing to bradycardia.
- Thyroid hormone replacement, if hypothyroidism is present.
- Electrolyte correction, if electrolyte abnormalities are identified.
- Pacemaker implantation, in severe symptomatic cases, as recommended in the 2018 ACC/AHA/HRS guideline on the evaluation and management of patients with bradycardia and cardiac conduction delay 1. Any postmenopausal woman with new-onset bradycardia should undergo a thorough evaluation, including medication review, thyroid function tests, electrolyte panel, and cardiac assessment, to determine the underlying cause and guide management.
From the FDA Drug Label
Catecholamine-depleting drugs (e. g., reserpine) may have an additive effect when given with beta-blocking agents, or monoamine oxidase (MAO) inhibitors. Observe patients treated with metoprolol plus a catecholamine depletor for evidence of hypotension or marked bradycardia, which may produce vertigo, syncope, or postural hypotension Digitalis Glycosides and Beta-Blockers Both digitalis glycosides and beta-blockers slow atrioventricular conduction and decrease heart rate. Concomitant use can increase the risk of bradycardia Catecholamine-depleting drugs (e.g., reserpine) may have an additive effect when given with beta-blocking agents. Patients treated with atenolol plus a catecholamine depletor should therefore be closely observed for evidence of hypotension and/or marked bradycardia which may produce vertigo, syncope, or postural hypotension. Both digitalis glycosides and beta-blockers slow atrioventricular conduction and decrease heart rate. Concomitant use can increase the risk of bradycardia
The causes of bradycardia in a postmenopausal female may include:
- Catecholamine-depleting drugs (e.g., reserpine) when given with beta-blocking agents
- Concomitant use of digitalis glycosides and beta-blockers
- Concomitant administration of a beta-adrenergic antagonist with a calcium channel blocker
- Concomitant use of prostaglandin synthase inhibiting drugs
- Withdrawal of clonidine in patients receiving concurrent clonidine and beta-adrenergic blocker 2 3
From the Research
Causes of Bradycardia
- Bradycardia is a heart rate lower than 60 beats/min and can be due to sinus, atrial, or junctional bradycardia or to a problem with the conduction system (eg, an atrioventricular block) 4
- Pathology that produces bradycardia may occur within the sinus node, atrioventricular (AV) nodal tissue, and the specialized His-Purkinje conduction system 5
Medication-Induced Bradycardia
- Beta-adrenergic receptor blockers (β-blockers) can cause bradycardia as a side effect, especially in patients with concomitant ischemic heart disease (IHD), heart failure, obstructive cardiomyopathy, aortic dissection or certain cardiac arrhythmias 6
- Beta blocker-induced bradycardia was associated with a significant increase in the average 24-hour values of RR variance and of the normalized power of the high-frequency component, whereas the low-frequency component was greatly reduced 7
Post-Menopausal Considerations
- There is no direct evidence in the provided studies to suggest specific causes of bradycardia in post-menopausal females, but it can be inferred that the usual causes of bradycardia, such as sinus node dysfunction or atrioventricular block, may still apply 4, 5
- Hormonal changes during menopause may affect the cardiovascular system, but the relationship between menopause and bradycardia is not explicitly discussed in the provided studies 4, 5, 6, 7