The angiotensin receptor blocker (ARB) losartan led to hypotension and failed to improve mortality in patients hospitalized for acute COVID-19, according to the randomized, prospective — and prematurely terminated — ARBs CORONA II trial.

Among 341 patients in Canada and France hospitalized for acute COVID-19, 39.8% of patients who were prescribed losartan developed serious adverse events (SAEs) versus 27.2% in the usual care group (P=0.01), largely due to hypotension in the losartan arm, James Russell, MD, of the University of British Columbia in Vancouver, and colleagues reported in Clinical Infectious Diseases.

However, in April 2023, the REMAP-CAP trial found that patients hospitalized for acute COVID-19 who were prescribed ARBs or angiotensin-converting enzyme (ACE) inhibitors had increased mortality and acute kidney injury rates. Consequently, leaders of the ARBs CORONA II trial stopped the trial early and then conducted an unplanned interim analysis when results indicated poorer outcomes with losartan.

Of note, at the time the trial was stopped, there was no significant difference in the original primary outcome of 28-day mortality between the losartan group (6.5%) and the usual care group (5.9%; OR 1.11, 95% CI 0.47-2.64, P =0.81).

However, patients with hypotensive SAEs had over five times the mortality rate compared with those without hypotension in both the losartan (OR 5.37, 95% CI 1.73-16.6) and the usual care arms (OR 6.8, 95% CI 2.00-23.15).

Use of ARBs or ACE inhibitors in patients with COVID-19 remains controversial. Three recent studies showed no benefit of renin angiotensin system inhibitors in managing COVID-19. And, one recent systematic review and meta-analysis found that initiation of renin angiotensin system blockers increases mortality in patients with severe or critical COVID-19. However, another review found that among hospitalized patients with COVID-19, ACE inhibitors or ARBs were not associated with increased mortality risk, ICU admission, or mechanical ventilation.

The National Institutes of Health COVID-19 treatment guidelines currently recommend that patients with COVID-19 who are receiving ARBs or ACE inhibitors should not stop taking the drugs unless discontinuation is otherwise warranted by their clinical condition.

The ARBs CORONA II prospective, open-label, randomized trial enrolled adults hospitalized with acute COVID-19 between October 2020 and March 2022. Exclusion criteria included acute kidney injury, hyperkalemia, hypotension, use of ARBs or ACE inhibitors within a week of presentation, pregnancy or breast feeding, among others.

Of 341 patients, 171 received losartan and 170 received usual care. Patients in the losartan group received oral losartan 25 to 100 mg/day within 72 hours of hospitalization, which was uptitrated according to treatment tolerance. Treatment with losartan or usual care continued for up to 3 months if a patient was still hospitalized. Of patients in the losartan arm, 65% were treated with 100 mg/day, the maximum dose. About 20% of patients discontinued losartan for SAEs.

The study authors also acknowledged several limitations. In addition to the trial being stopped for safety concerns, there was no placebo group. Also, mortality was lower than expected and may have been due to changes in the virulence of SARS-CoV-2 variants or to newer interventions. Losartan doses may have not been optimal and other ARBs may have proven more effective in reducing mortality, the authors noted.