Does Losartan Affect Heart Rate?
Losartan does not significantly affect heart rate in clinical practice. 1
Pharmacodynamic Evidence
The FDA label for losartan explicitly states: "There was essentially no change in average heart rate in losartan-treated patients in controlled trials." 1 This neutral effect on heart rate distinguishes losartan from beta-blockers, which predictably lower heart rate through direct chronotropic inhibition. 1
The mechanism explains this finding: losartan selectively blocks the angiotensin II type 1 (AT1) receptor, inhibiting vasoconstriction and aldosterone secretion, but it does not interact with cardiac ion channels, beta-adrenergic receptors, or other pathways that directly regulate sinus node automaticity. 1
Clinical Trial Data
Multiple randomized controlled trials using 24-hour ambulatory blood pressure monitoring confirm that losartan lowers blood pressure without changing heart rate:
In a placebo-controlled trial of 122 patients with mild-to-moderate hypertension, losartan at doses of 50 mg once daily, 100 mg once daily, and 50 mg twice daily produced sustained 24-hour blood pressure reduction but "had no significant effect on heart rate." 2
A separate ambulatory monitoring study in 16 hypertensive patients found that losartan reduced blood pressure from 146/89 mmHg to 134/82 mmHg without altering heart rate. 3
In salt-depleted conscious dogs receiving losartan 30 µg/min/kg, mean arterial pressure fell from 110.9 to 95.0 mmHg, but heart rate increased from 84.6 to 103 beats/min—a reflex tachycardia response to vasodilation, not a direct drug effect. 4 This animal model demonstrates that losartan does not suppress the normal baroreceptor reflex.
Comparative Evidence: Losartan vs. Beta-Blockers
A head-to-head crossover trial in 17 hypertensive patients (similar to the LIFE study population) directly compared losartan with atenolol over four months. Heart rate was significantly lower on atenolol than on losartan (p = 0.03), confirming that losartan lacks the bradycardic effect characteristic of beta-blockade. 5 This difference is clinically relevant: the LIFE trial showed losartan was superior to atenolol in reducing cardiovascular events and stroke in patients with left ventricular hypertrophy, and the absence of heart rate reduction may contribute to losartan's favorable tolerability profile. 6, 5
Clinical Implications
Losartan is an appropriate choice for patients who cannot tolerate beta-blocker–induced bradycardia or who require blood pressure control without heart rate reduction (e.g., athletes, patients with baseline bradycardia). 7
If a patient on losartan reports palpitations, the drug itself is unlikely to be the cause; the American Heart Association notes that losartan has a "notably favorable cardiac tolerability profile" regarding rhythm disturbances. 7 Instead, investigate metabolic causes (hypokalemia, hypomagnesemia) or concurrent medications. 7
Losartan does not mask tachycardia in conditions such as hyperthyroidism, sepsis, or volume depletion, unlike beta-blockers. 1
Monitoring Recommendations
Although losartan does not alter heart rate, the European Society of Cardiology recommends checking serum electrolytes and renal function within 1–2 weeks of initiation, because metabolic disturbances (hyperkalemia, acute kidney injury) could indirectly manifest as arrhythmias or palpitations. 7 Routine heart rate monitoring is not required for losartan therapy itself. 1