Will Enalaprilat Lower Heart Rate?
No, enalaprilat will not lower heart rate—ACE inhibitors like enalaprilat reduce blood pressure by decreasing peripheral vascular resistance without causing a decrease in heart rate, and in fact may slightly reduce heart rate during peak exercise but do not cause bradycardia at rest. 1, 2, 3
Mechanism and Hemodynamic Effects
Enalaprilat works by inhibiting angiotensin-converting enzyme, which lowers peripheral vascular resistance and blood pressure without the reflex tachycardia or bradycardia seen with other antihypertensive classes 2, 4. The key hemodynamic profile includes:
- Blood pressure reduction occurs through decreased systemic vascular resistance, not through negative chronotropic effects 2, 3
- Cardiac output is slightly increased or maintained, not decreased 4
- Cardiovascular reflexes remain intact and are not impaired 4
- Heart rate at rest remains unchanged with enalapril therapy 5, 4
Exercise and Heart Rate Response
In patients undergoing treadmill exercise testing, enalapril demonstrated a modest effect on heart rate only during peak exertion:
- Heart rate at rest was not significantly changed by enalapril 5
- Heart rate at peak exercise showed a small but significant decrease (P < 0.05) 5
- Heart rate during recovery period was not significantly affected 5
This minimal effect on exercise heart rate is clinically insignificant and does not represent bradycardia 5.
Clinical Relevance for Your Patient
In a patient with existing bradycardia, enalaprilat is an appropriate choice because it does not worsen heart rate 1, 2. This is a critical distinction from other antihypertensive classes:
- Beta-blockers cause bradycardia and would be contraindicated in your bradycardic patient 1
- Non-dihydropyridine calcium channel blockers (verapamil, diltiazem) also reduce heart rate and should be avoided 1
- Enalaprilat is specifically listed as appropriate for hypertensive emergencies, including acute left ventricular failure, with onset of action in 15-30 minutes and duration of 6-12 hours 1
Important Caveats
The main concern with enalaprilat in acute settings is precipitous blood pressure drop in high-renin states, not bradycardia 1. Monitor for:
- Excessive hypotension, particularly in volume-depleted patients 2, 4
- Variable blood pressure response depending on renin-angiotensin system activity 1
- Potential for reduced renal function in bilateral renal artery stenosis 2
Enalaprilat should be avoided in acute myocardial infarction according to guidelines, though this is based on timing and hemodynamic considerations, not heart rate effects 1.