CHICAGO – The choice of loop diuretic for decongestion in patients hospitalized with heart failure (HF) may make little difference to survival or readmission risk over the next year, at least when deciding between furosemide or torsemide, a randomized trial suggests.
Both drugs are old and widely used, but differences between the two loop diuretics in bioavailability, effects on potassium levels, and other features have led some clinicians to sometimes prefer torsemide. Until now, however, no randomized HF trials have compared the two drugs.
The new findings suggest clinicians can continue starting such patients with HF on either agent, at their discretion, without concern that the choice may compromise outcomes, say researchers from the TRANSFORM-HF trial, which compared furosemide-first and torsemide-first diuretic strategies in a diverse population of patients with HF.
Given that the two strategies were similarly effective for survival and rehospitalization, clinicians caring for patients with HF can focus more on “getting patients on the right dose for their loop diuretic, and prioritizing those therapies proven to improve clinical outcomes,” said Robert J. Mentz, MD, of Duke University Clinical Research Institute, Durham, N.C.
Dr. Mentz, a TRANSFORM-HF principal investigator, presented the primary results November 5 at the American Heart Association scientific sessions.
The trial had randomly assigned 2,859 patients hospitalized with HF and with a plan for oral loop diuretic therapy to initiate treatment with furosemide or torsemide. Clinicians were encouraged to maintain patients on the assigned diuretic, but crossovers to the other drug or other diuretic changes were allowed.
Rates of death from any cause, the primary endpoint, were about 26% in both groups over a median 17-month follow-up, regardless of ejection fraction (EF).
The composite rates of all-cause death or hospitalization at 12 months were also not significantly different, about 49% for those started on furosemide and about 47% for patients initially prescribed torsemide.
As a pragmatic comparative effectiveness trial, TRANSFORM-HF entered diverse patients with HF, broadly representative of actual clinical practice, who were managed according to routine practice and a streamlined study protocol at more than 60 U.S. centers, Dr. Mentz observed.
One of the pragmatic design’s advantages, he told this news organization, was “how efficient it was” as a randomized comparison of treatment strategies for clinical outcomes. It was “relatively low cost” and recruited patients quickly, compared with conventional randomized trials, “and we answered the question clearly.” The trial’s results, Dr. Mentz said, reflect “what happens in the real world.”
When might torsemide have the edge?
Although furosemide is the most commonly used loop diuretic in HF, and there are others besides it and torsemide, the latter has both known and theoretical advantages that set it apart. Torsemide is more than twice as potent as furosemide and more bioavailable, and its treatment effect lasts longer, the TRANSFORM-HF investigators have noted.
In addition, preclinical and small clinical studies suggest torsemide may have pleiotropic effects that might be theoretical advantages for patients with HF. For example, it appears to downregulate the renin-angiotensin-aldosterone system (RAAS) and reduce myocardial fibrosis and promote reverse ventricular remodeling, the group writes.
In practice, therefore, torsemide may be preferred in patients with furosemide resistance or “challenges with bioavailability, especially those with very advanced heart failure with congestion who may have gut edema, where oral furosemide and other loop diuretics are not effectively absorbed,” Biykem Bozkurt, MD, PhD, Baylor College of Medicine, Houston, told this news organization.
In such patients, she said, torsemide “is considered to be a better choice for individuals who have diuretic resistance with advanced congestion.”
The drug’s apparent pleiotropic effects, such as RAAS inhibition, may have less relevance to the TRANSFORM-HF primary endpoint of all-cause mortality than to clinical outcomes more likely associated with successful decongestion, such as HF hospitalization, Dr. Bozkurt proposed.
The trial’s pragmatic design, however, made it more feasible to focus on all-cause mortality and less practical to use measures of successful decongestion, such as volume loss or reduction in natriuretic peptide levels, she observed. Those are endpoints of special interest when diuretics are compared, “especially for the subgroup of patients who are diuretic resistant.”
Over the last 20 years or so, “we’ve learned that hospitalized heart failure is a very different disease process with a different natural history,” observed Clyde W. Yancy, MD, MSc, Northwestern University, Chicago, who was not part of the current study.
“So, the idea that something as nuanced as choice of one loop diuretic over the other, in that setting, would be sufficient to change the natural history, may be still a high bar for us,” he said in an interview.
“Based on these data, one would have to argue that whichever loop diuretic you select for the hospitalized patient – and a lot of that is driven by market exigencies right now – it turns out that the response is indistinguishable,” Dr. Yancy said. “That means if your hospital happens to have furosemide on the formulary, use it. If furosemide is not available but torsemide is available, use it.”
Dr. Yancy said he’d like to see a trial similar to TRANSFORM-HF but in outpatients receiving today’s guideline-directed medical therapy, which includes the sodium-glucose cotransporter 2 (SGLT2) inhibitors, drugs that increase the fractional excretion of sodium and have a “diureticlike” effect.
Such a trial, he said, would explore “the combination of not one, or two, but three agents with a diuretic effect – a loop diuretic, a mineralocorticoid antagonist, and an SGLT2 inhibitor – in ambulatory, optimized patients. It might make a difference.”