Does Dobutamine Increase Heart Rate?
Yes, dobutamine consistently increases heart rate in a dose-dependent manner, with heart rate typically rising 2- to 3-fold during infusion. 1
Mechanism of Action
Dobutamine acts directly on β-1 adrenergic receptors of the myocardium, producing both increased contractility and increased heart rate as primary effects. 1 The FDA label explicitly warns that dobutamine may cause a marked increase in heart rate, with approximately 10% of patients experiencing rate increases of 30 beats/minute or more in clinical studies. 2
Magnitude of Heart Rate Increase
The heart rate response follows a predictable dose-dependent pattern:
- At baseline to peak infusion: Heart rate increases from approximately 72 bpm to 117 bpm (an increase of ~45 bpm). 3
- Two- to three-fold increase: This is the expected magnitude during standard stress testing protocols. 1
- Significant increases at each dose step: Heart rate rises significantly with each incremental dose increase during stress echocardiography, except at the highest doses (≥40-50 mcg/kg/min) where it may plateau. 3
Dose-Response Relationship
The chronotropic (heart rate) effect varies by dose:
- Low doses (2-5 mcg/kg/min): Heart rate may remain relatively stable, with cardiac output increases primarily from improved stroke volume. 4
- Higher doses (>5 mcg/kg/min): Heart rate becomes the dominant mechanism for increasing cardiac output, as stroke volume plateaus or even decreases. 4, 5
- Peak doses (40-50 mcg/kg/min): Heart rate reaches maximum with target of 85% age-predicted maximum during stress testing. 1
Clinical Implications and Monitoring
Common pitfall: The heart rate increase is substantial enough that it serves as one of the primary endpoints during dobutamine stress testing—"adequate heart rate response" is a formal stopping criterion. 1
Important consideration: In patients with atrial fibrillation, dobutamine facilitates atrioventricular conduction and can cause rapid ventricular response, requiring digitalis pretreatment before dobutamine administration. 2
Monitoring requirement: ECG, heart rate, and blood pressure must be monitored during each stage of dobutamine infusion. 1 The American Heart Association recommends having esmolol (0.5 mg/kg) readily available to rapidly reverse dobutamine's effects if excessive tachycardia occurs. 6
Age-Related Variation
The heart rate response decreases with age—the slope of heart rate versus dobutamine dose decreases by 2.71% per year of age. 5 This means elderly patients may have a more attenuated chronotropic response compared to younger patients.
When Heart Rate Increase is Inadequate
If adequate heart rate is not achieved during stress testing despite maximal dobutamine dosing, up to 1 mg of intravenous atropine may be administered to augment the chronotropic response. 1