Can PVCs Cause Thyroid Abnormalities?
No, premature ventricular contractions (PVCs) do not cause thyroid abnormalities—the relationship is reversed: thyroid dysfunction can cause or exacerbate cardiac arrhythmias including PVCs.
The Correct Causal Relationship
Thyroid abnormalities cause cardiac arrhythmias, not the other way around. The evidence consistently demonstrates that thyroid dysfunction affects cardiac rhythm through metabolic and electrophysiologic mechanisms 1, 2.
Thyroid Dysfunction Leading to Arrhythmias
- Hyperthyroidism increases arrhythmia risk: Subclinical hyperthyroidism is associated with a nearly 2-fold increased risk of developing atrial fibrillation (adjusted hazard ratio 1.98; 95% CI, 1.29-3.03) 2
- Thyrotoxicosis requires rate control: Beta-blockers are recommended to control ventricular response in patients with arrhythmias complicating thyrotoxicosis 1
- Thyroid normalization is essential: When rhythm control is desired in thyroid-related arrhythmias, thyroid function must be normalized prior to cardioversion, as the risk of arrhythmia relapse remains high otherwise 1
Clinical Evaluation When Both Are Present
When a patient presents with PVCs, thyroid dysfunction should be evaluated as a potentially reversible cause 3, 4:
- Screen for hyperthyroidism: Thyroid function testing is part of the standard workup for patients with PVCs to identify reversible causes 3, 4
- Treat the underlying thyroid disorder: Management should focus on identifying and treating underlying causes such as hyperthyroidism before attributing symptoms solely to the PVCs 4
Management Implications for Bradycardia and AV Block
The 2019 ACC/AHA/HRS guidelines specifically address thyroid-related conduction abnormalities 1:
- Permanent pacing may be considered in patients with symptomatic second-degree or third-degree AV block associated with thyroid function abnormalities but without clinical myxedema, though observation for reversibility after thyroid normalization is reasonable (Class IIb recommendation) 1
- This reflects the potentially reversible nature of thyroid-induced conduction abnormalities 1
Common Pitfall to Avoid
Do not assume PVCs are causing metabolic or endocrine changes. PVCs are electrical phenomena that do not produce hormonal alterations. When both PVCs and thyroid abnormalities coexist, always investigate the thyroid disorder as a potential cause of the arrhythmia, not as a consequence 3, 4.
The proper clinical approach is to screen for thyroid dysfunction when evaluating any patient with new or symptomatic PVCs, as correcting thyroid abnormalities may resolve or reduce the arrhythmic burden 1, 3, 4.