Can iron infusion cause an increase in heart rate (tachycardia)?

Can Iron Infusion Cause Increased Heart Rate?

Yes, iron infusion can acutely increase heart rate as part of infusion reactions, but this is distinct from the chronic tachycardia caused by untreated anemia itself.

Acute Tachycardia During Iron Infusion

Iron infusions can trigger palpitations and tachycardia as part of complement activation-related pseudo-allergy (CARPA) reactions, occurring within 30 minutes of administration. 1

Mechanism of Infusion-Related Tachycardia

• The heart rate increase during iron infusion is mediated by complement activation triggered by iron nanoparticles, not true IgE-mediated allergic reactions 1
• This represents a hypersensitivity reaction that can manifest with isolated palpitations or as part of a broader systemic response including hypotension and dyspnea 1, 2
• These reactions are self-limiting in most cases and resolve spontaneously within 15 minutes with supportive care 1

Management of Infusion-Related Tachycardia

If palpitations or tachycardia occur during iron infusion, immediately stop the infusion and switch to normal saline at keep-vein-open rate. 1

• Monitor the patient for at least 15 minutes, as most reactions resolve without intervention 1
• Do not administer first-generation antihistamines or vasopressors, as these can paradoxically convert minor reactions into hemodynamically significant adverse events, including exacerbation of tachycardia 1, 2
• If symptoms persist beyond 15 minutes, administer IV hydrocortisone 200 mg 1
• Only consider rechallenge if symptoms completely resolve, restarting at 50% of the initial infusion rate 1

Prevention Strategies

• Use slower infusion rates (100 mg over 60 minutes rather than faster rates) to minimize infusion reactions 1
• Consider switching to alternative IV iron formulations if reactions recur 1

Chronic Tachycardia from Anemia (Not the Iron Infusion)

The more clinically significant tachycardia in iron-deficient patients is caused by the anemia itself, not the iron replacement therapy.

Physiologic Compensation for Anemia

• Chronic anemia necessitates increased cardiac output to compensate for impaired tissue oxygenation, which raises heart rate and increases ventricular preload 3
• This compensatory tachycardia can lead to a dilated, strongly contractile left ventricle with gradual deterioration of contractile reserve 3
• In patients with β-thalassemia major, the chronic high-output state produces volume-loaded ventricles with elevated heart rate and stroke volume as physiological compensation 3

Clinical Context

• Mild tachycardia and cardiomegaly in chronically anemic patients should be viewed as physiological compensation rather than pathological findings 3
• The hyperdynamic circulation characteristic of chronic anemia accounts for increased reference ranges for ventricular ejection fractions in these patients 3
• An overstrained ventricle from chronic anemia may be more susceptible to effects of iron overload if it develops 3

Important Clinical Distinction

Correcting anemia with iron infusion actually reduces chronic tachycardia by eliminating the need for compensatory increased cardiac output. 3

• Favorably impacting iron accumulation and correcting anemia decreases chronic cardiac workload and compensatory hypertrophy 3
• Maintaining hemoglobin levels above 10 g/dL reduces the cardiac stress from chronic anemia 3

Rare Severe Complications

• In pregnant women, severe hypersensitivity reactions to iron infusion can cause maternal respiratory compromise leading to fetal bradycardia, though this is extremely rare 4
• Severe anemia itself has been associated with supraventricular tachycardia in pediatric cases, representing a cardiac complication of untreated iron deficiency 5