Post-COVID cardiac trial shows losartan-prednisolone combo fails primary endpoint

Years into the pandemic's aftermath, thousands of people still report chest pain, shortness of breath, and a racing heart—yet their hearts look structurally normal on standard tests. The problem, researchers have come to understand, lies not in the architecture of the organ but in its chemistry: immune dysregulation, damaged blood vessel linings, and low-grade inflammation smoldering in the cardiac tissue itself. For these patients, there has been no proven treatment. Now a major international trial has tested what seemed like a reasonable approach, and the results offer a cautionary lesson about the limits of straightforward immunosuppression.

Myoflame-19 enrolled 279 people across multiple centers who had documented inflammatory changes in their hearts visible on advanced cardiac imaging—specifically, cardiovascular magnetic resonance scans that can detect inflammation invisible to conventional echocardiography. Researchers divided them roughly in half: 139 received losartan, a blood pressure medication that can dampen certain inflammatory pathways, combined with prednisolone, a corticosteroid. The other 140 received matching placebos. Both groups were followed for 16 weeks. The trial was rigorous—double-blind, randomized, with a prespecified primary outcome chosen before any results were known.

That primary outcome was change in left ventricular ejection fraction, the percentage of blood the heart's main pumping chamber ejects with each beat. It's a fundamental measure of cardiac function. The researchers hoped the drug combination would improve it. Instead, the treatment group showed virtually no advantage: a difference of 0.74 percentage points compared to placebo, a gap so small it could easily be noise. The statistical test confirmed it was not significant. The result was, in the language of clinical trials, neutral—a polite way of saying the treatment did not work.

But the story did not end there. Among the secondary endpoints—measures the researchers had specified in advance but considered less critical—several showed numerical improvements favoring the drug combination. Chest pain scores dropped more in the treatment group than placebo. Functional capacity, measured by New York Heart Association classification, improved slightly more with active treatment. The overall burden of long COVID symptoms trended downward. Even some of the cardiac imaging markers—native T1 and T2 relaxation times, which reflect tissue inflammation—showed modest improvements. Yet none of these secondary findings crossed the threshold of statistical significance. The confidence intervals, the ranges within which the true effect likely lies, all included zero, meaning the improvements could plausibly be due to chance alone.

What makes this result particularly instructive is not that it failed, but how it failed. The treatment was safe and well-tolerated. No serious adverse events emerged. Patients did not suffer harm from the intervention. The drug combination made biological sense: losartan targets endothelial dysfunction and certain inflammatory pathways; prednisolone broadly suppresses immune activation. Yet this rational approach to a rational hypothesis produced no clear benefit on the measure that matters most—actual cardiac function.

The implications ripple outward. Post-COVID cardiac syndrome remains a significant clinical problem. Thousands of people are functionally limited by symptoms that persist months or years after infection, unable to exercise, unable to work, unable to return to their previous lives. The absence of structural disease makes the condition harder to treat and easier to dismiss. This trial, by failing to show benefit from a plausible immunomodulatory strategy, suggests that the underlying biology may be more complex than simple immune dysregulation, or that the specific mechanisms targeted by these drugs are not the critical ones. It also raises questions about trial design: perhaps secondary endpoints that showed numerical improvements warrant further investigation, or perhaps they were simply noise, and chasing them would lead researchers down a dead end.

For now, the trial has closed one door while leaving others open. Researchers know that losartan plus prednisolone is not the answer. What comes next—whether alternative immunomodulatory approaches, different drug combinations, or entirely different treatment strategies—remains to be determined. The patients waiting for relief from persistent cardiac symptoms will have to keep waiting.