Can hypothyroidism cause chest pain or arrhythmias such as bigeminy?

Hypothyroidism and Cardiac Manifestations

Hypothyroidism typically does not cause chest pain or bigeminy directly, but it can cause ventricular arrhythmias in severe cases and may contribute to angina through its cardiovascular effects. The relationship between hypothyroidism and cardiac symptoms is complex and differs significantly from hyperthyroidism.

Direct Cardiac Effects of Hypothyroidism

Bradycardia, not tachyarrhythmias, is the hallmark cardiac manifestation of hypothyroidism. 1 The typical cardiovascular profile includes:

• Bradycardia is one of the most common cardiovascular manifestations 1
• Increased systemic vascular resistance by as much as 50% 1
• Diastolic hypertension due to increased peripheral resistance 1
• Low cardiac output from the combination of bradycardia, decreased ventricular filling, and decreased cardiac contractility 1

Chest Pain in Hypothyroidism

Chest pain can occur in hypothyroid patients, but the mechanism is indirect rather than a primary manifestation. A retrospective analysis of 38 hypothyroid patients with chest pain undergoing cardiac catheterization found significantly reduced cardiac index in hypothyroid patients compared to euthyroid controls 2. The chest pain likely results from:

• Reduced cardiac output and coronary perfusion due to hemodynamic changes 1, 2
• Increased myocardial oxygen demand relative to supply from diastolic hypertension 1
• Coronary atherosclerosis acceleration from metabolic derangements, though this is not explicitly stated in the evidence

Arrhythmias in Hypothyroidism

Hypothyroidism is paradoxically associated with ventricular arrhythmias, not the atrial arrhythmias typical of hyperthyroidism. 3 This is a critical distinction:

Ventricular Arrhythmias (More Common)

• Hypothyroidism increases ventricular arrhythmia risk, including polymorphic ventricular tachycardia and Torsades de Pointes 3, 4, 5
• Severe hypothyroidism can precipitate life-threatening ventricular tachycardia, as documented in multiple case reports 4, 5
• QT interval prolongation is common and predisposes to Torsades de Pointes 4

Supraventricular Arrhythmias (Rare)

• Supraventricular tachycardia can rarely occur with severe hypothyroidism, though this is atypical 6
• Bigeminy specifically is not well-documented as a manifestation of hypothyroidism in the provided evidence

Important Context

Hypothyroidism is also associated with increased atrial fibrillation risk, particularly in elderly patients. 7 This appears counterintuitive but is well-documented in both animal models and human studies 7.

Critical Clinical Pitfall

Overtreatment with levothyroxine can cause angina and arrhythmias. The FDA product label for levothyroxine cites possible adverse effects on the cardiovascular system, including angina, arrhythmia, and increased cardiac wall thickness 7. One quarter of patients receiving levothyroxine are inadvertently maintained on doses high enough to make TSH levels undetectable, potentially increasing risk for abnormal cardiac output 7.

Management Approach

Thyroid hormone replacement is the cornerstone of treatment for hypothyroidism-induced cardiac manifestations:

• Initiate levothyroxine replacement therapy for documented hypothyroidism with cardiac symptoms 4, 5
• Ventricular arrhythmias typically resolve after stabilization of thyroid hormone levels 4, 5
• Coronary artery bypass can be performed safely despite hypothyroidism without requiring full thyroid replacement preoperatively 2
• Monitor for improvement in cardiac function, as left ventricular dysfunction from hypothyroidism typically normalizes with treatment 5
• Consider comprehensive cardiac evaluation including genetic testing if ventricular arrhythmias persist, as hypothyroidism may unmask underlying channelopathies 4

In patients presenting with chest pain or arrhythmias, thyroid function testing is recommended to identify potential thyroid dysfunction as a contributing factor 1.