Lisinopril Does Not Lower Heart Rate
Lisinopril, an angiotensin-converting enzyme (ACE) inhibitor, does not significantly affect heart rate in hypertensive patients. The clinical pharmacology data shows that lisinopril produces a smooth, gradual blood pressure reduction without affecting heart rate or cardiovascular reflexes 1.
Mechanism of Action and Hemodynamic Effects
- Lisinopril works primarily by inhibiting ACE activity, which reduces plasma angiotensin II and aldosterone while increasing plasma renin activity 1.
- In hemodynamic studies of lisinopril in patients with essential hypertension, blood pressure reduction was accompanied by a reduction in peripheral arterial resistance with little or no change in cardiac output and heart rate 2.
- Unlike beta-blockers or certain calcium channel blockers (such as verapamil or diltiazem), ACE inhibitors like lisinopril do not directly affect the sinoatrial node or cardiac conduction system 3.
Clinical Evidence
- In a study using ambulatory blood pressure monitoring in patients with moderate hypertension, lisinopril effectively reduced blood pressure but did not alter heart rate 4.
- When compared with other antihypertensive medications in clinical trials, lisinopril demonstrated superior reductions of systolic and diastolic blood pressure compared to hydrochlorothiazide, and was approximately equivalent to atenolol and metoprolol in reducing diastolic blood pressure, but without the heart rate-lowering effects typically seen with beta-blockers 2, 5.
- In patients with heart failure and atrial fibrillation, lisinopril improved peak oxygen consumption but did not significantly affect heart rate during exercise or ambulatory monitoring 6.
Contrast with Other Antihypertensive Medications
- Unlike beta-blockers (such as atenolol or metoprolol) which directly reduce heart rate as part of their mechanism of action, ACE inhibitors like lisinopril lower blood pressure primarily through vasodilation 3.
- Certain calcium channel blockers, particularly non-dihydropyridines like diltiazem and verapamil, can significantly reduce heart rate, unlike ACE inhibitors 3.
- Ivabradine is specifically designed to lower heart rate by inhibiting the If current in the sinus node, a mechanism completely different from lisinopril's ACE inhibition 3.
Clinical Implications
- When heart rate reduction is a therapeutic goal (such as in certain cases of angina or inappropriate tachycardia), medications like beta-blockers or ivabradine would be more appropriate choices than lisinopril 3.
- The lack of heart rate reduction with lisinopril may be advantageous in patients where bradycardia would be problematic or where maintaining cardiac output is important 3.
- In patients with heart failure, lisinopril increases cardiac output and decreases pulmonary capillary wedge pressure and mean arterial pressure without significant changes in heart rate 2.
Common Misconceptions
- It's important to distinguish between the effects of different antihypertensive drug classes - while some (beta-blockers, non-dihydropyridine calcium channel blockers) directly reduce heart rate, ACE inhibitors like lisinopril do not 3.
- The blood pressure lowering effect of lisinopril begins within 2 hours, peaks around 6 hours, and lasts for at least 24 hours, but throughout this cycle, there is no significant impact on heart rate 1.