Can pernicious anemia lead to palpitations?

Can Pernicious Anemia Lead to Palpitations?

Yes, pernicious anemia can definitely cause palpitations through multiple cardiovascular mechanisms related to chronic anemia and vitamin B12 deficiency. 1, 2

Pathophysiological Mechanisms

Compensatory Cardiac Response to Anemia

• The decreased oxygen-carrying capacity from low hemoglobin triggers the heart to increase cardiac output by up to 60% above normal levels to maintain adequate tissue oxygen delivery. 1, 3
• This compensatory tachycardia is the primary mechanism causing palpitations in pernicious anemia patients. 1
• Peripheral arterial vasodilation occurs simultaneously to lower systemic vascular resistance, creating a hyperdynamic circulatory state. 3

Severity-Dependent Cardiac Effects

• Mild anemia (hemoglobin 9-12 g/dL) causes modest tachycardia that may be asymptomatic at rest but becomes noticeable with exertion. 1
• Severe anemia (hemoglobin <7 g/dL) produces marked tachycardia with ST-T wave changes and significantly increased risk of cardiac decompensation. 1
• The wide pulse pressure and hyperdynamic precordium characteristic of severe anemia further contribute to the sensation of palpitations. 3

Arrhythmia Risk

Direct Arrhythmogenic Effects

• Chronic anemia-induced tachycardia can progress to cardiac remodeling and dysfunction, increasing the risk of arrhythmias including atrial fibrillation and supraventricular tachycardia. 1
• Anemia increases heart rate and cardiac output, leading to left ventricular hypertrophy and creating an imbalance between myocardial oxygen demand and supply. 4, 2
• Low hemoglobin levels significantly increase cardiovascular events, with an odds ratio of 1.45 per 1 g/dL decrease in hemoglobin. 2

Additional Cardiac Complications

• Anemia can worsen pre-existing heart failure, which itself predisposes to arrhythmias and palpitations. 1
• Electrolyte abnormalities that may accompany pernicious anemia (particularly hypokalemia) can trigger arrhythmias. 2

Clinical Presentation in Pernicious Anemia

Common Cardiovascular Symptoms

• Palpitations are part of the typical presentation of pernicious anemia, along with fatigue, weakness, and pale appearance. 5
• Patients may experience cardiac symptoms including palpitations even before developing severe anemia, as they gradually acclimatize to the insidious onset. 6
• In severe cases, pernicious anemia can present with collapse and clinical features of cardiac failure. 7

Hematological Findings

• Pernicious anemia presents with macrocytic anemia (elevated mean corpuscular volume) and low vitamin B12 levels. 5, 7
• Pancytopenia may occur in severe cases. 7
• Anti-intrinsic factor or anti-parietal cell antibodies are found in 96% of patients. 8

Clinical Management Implications

Screening Recommendations

• Screen for anemia using complete blood count in patients with unexplained tachycardia or palpitations, as even mild anemia is an independent risk factor for adverse outcomes. 1
• Evaluate for vitamin B12 deficiency when macrocytic anemia is present. 5
• Consider baseline endoscopy with biopsies in individuals aged ≥50 years with laboratory evidence of pernicious anemia. 4

Treatment Response

• Intramuscular vitamin B12 replacement is the most effective treatment and leads to near-complete resolution of cardiovascular symptoms including palpitations. 5, 7
• Correction of anemia improves cardiovascular outcomes and resolves the compensatory tachycardia. 3
• Patients improve steadily with concomitant improvement in hematological indices following B12 replacement. 7

Important Clinical Pitfalls

• Pernicious anemia is often underdiagnosed because the insidious onset allows patients to acclimatize to symptoms, and palpitations may be attributed to other causes. 6, 9
• The presence of palpitations in an anemic patient does not exclude concurrent cardiac pathology—diastolic murmurs always indicate structural heart disease and cannot be attributed to anemia alone. 3
• Delayed recognition can lead to irreversible neurological sequelae despite treating the anemia, so prompt diagnosis is critical. 6, 5
• Associated autoimmune disorders (particularly autoimmune thyroid disease and vitiligo) are common and should be screened for. 4, 5, 8