Black HFrEF Patients Get More Empagliflozin Benefit in EMPEROR Analyses

Mitchel L. Zoler, PhD

December 21, 2022

CHICAGO – Black patients with heart failure with reduced ejection fraction (HFrEF) may receive more benefit from treatment with a sodium-glucose cotransporter-2 (SGLT2) inhibitor than do White patients, according to a new report.

A secondary analysis of data collected from the pivotal trials that assessed the SGLT2 inhibitor empagliflozin in patients with HFrEF, EMPEROR-Reduced, and in patients with heart failure with preserved ejection fraction (HFpEF), EMPEROR-Preserved, was presented by Subodh Verma, MD, PhD, at the American Heart Association scientific sessions.

The "hypothesis-generating" analysis of data from EMPEROR-Reduced showed "a suggestion of a greater benefit of empagliflozin" in Black, compared with White patients, for the study's primary endpoint (cardiovascular death or hospitalization for heart failure) as well as for first and total hospitalizations for heart failure, he reported.

However, a similar but separate analysis that compared Black and White patients with heart failure who received treatment with a second agent, dapagliflozin, from the same SGLT2-inhibitor class did not show any suggestion of heterogeneity in the drug's effect based on race.

Race-Linked Heterogeneity in Empagliflozin's Effect

In EMPEROR-Reduced, which randomized 3,730 patients with heart failure and a left ventricular ejection fraction of 40% or less, treatment of White patients with empagliflozin (Jardiance) produced a nonsignificant 16% relative reduction in the rate of the primary endpoint, compared with placebo, during a median 16-month follow-up.

By contrast, among Black patients, treatment with empagliflozin produced a significant 56% reduction in the primary endpoint, compared with placebo-treated patients, a significant heterogeneity (= .02) in effect between the two race subgroups, said Verma, a cardiac surgeon and professor at the University of Toronto.

The analysis he reported used combined data from EMPEROR-Reduced and the companion trial EMPEROR-Preserved, which randomized 5,988 patients with heart failure and a left ventricular ejection fraction greater than 40% to treatment with either empagliflozin or placebo and followed them for a median of 26 months.

To assess the effects of the randomized treatments in the two racial subgroups, Verma and associates used pooled data from both trials, but only from the 3,502 patients enrolled in the Americas, which included 3,024 White patients and 478 Black patients. Analysis of the patients in this subgroup who were randomized to placebo showed a significantly excess rate of the primary outcome among Blacks, who tallied 49% more of the primary outcome events during follow-up than did White patients, Verma reported. The absolute rate of the primary outcome without empagliflozin treatment was 13.15 events/100 patient-years of follow-up in White patients and 20.83 events/100 patient-years in Black patients.

The impact of empagliflozin was not statistically heterogeneous in the total pool of patients that included both those with HFrEF and those with HFpEF. The drug reduced the primary outcome incidence by a significant 20% in White patients, and by a significant 44% among Black patients.

But this point-estimate difference in efficacy, when coupled with the underlying difference in risk for an event between the two racial groups, meant that the number-needed-to-treat to prevent one primary outcome event was 42 among White patients and 12 among Black patients.

Race-Linked Treatment Responses Only in HFrEF

This suggestion of an imbalance in treatment efficacy was especially apparent among patients with HFrEF. In addition to the heterogeneity for the primary outcome, the Black and White subgroups also showed significantly divergent results for the outcomes of first hospitalization for heart failure, with a nonsignificant 21% relative reduction with empagliflozin treatment in Whites but a significant 65% relative cut in this endpoint with empagliflozin in Blacks, and for total hospitalizations for heart failure, which showed a similar level of significant heterogeneity between the two race subgroups.

In contrast, the patients with HFpEF showed no signal at all for heterogeneous outcome rates between Black and White subgroups.

One other study outcome, change in symptom burden measured by the Kansas City Cardiomyopathy Questionnaire (KCCQ), also showed suggestion of a race-based imbalance. The adjusted mean difference from baseline in the KCCQ clinical summary score was 1.50 points higher with empagliflozin treatment, compared with placebo among all White patients (those with HFrEF and those with HFpEF), and compared with a 5.25-point increase with empagliflozin over placebo among all Black patients with heart failure in the pooled American EMPEROR dataset, a difference between White and Black patients that just missed significance (= .06). Again, this difference was especially notable and significant among the patients with HFrEF, where the adjusted mean difference in KCCQ was a 0.77-point increase in White patients and a 6.71-point increase among Black patients (= .043),

These results also appeared in a report published simultaneously with Verma's talk.

But two other analyses that assessed a possible race-based difference in empagliflozin's effect on renal protection and on functional status showed no suggestion of heterogeneity.

Verma stressed caution about the limitations of these analyses because they involved a relatively small number of Black patients, and were possibly subject to unadjusted confounding from differences in baseline characteristics between the Black and White patients.

Black Patients Also Had a Number-Needed-to-Treat Advantage With Dapagliflozin

The finding that Black patients with heart failure potentially get more bang for the buck from treatment with an SGLT2 inhibitor by having a lower number needed to treat also showed up in a separate report at the meeting that assessed the treatment effect from dapagliflozin (Farxiga) in Black and White patients in a pooled analysis of the DAPA-HF pivotal trial of patients with HFrEF and the DELIVER pivotal trial of patients with HFpEF. The pooled cohort included a total of 11,007, but for the analysis by race the investigators also limited their focus to patients from the Americas with 2,626 White patients and 381 Black patients.

Assessment of the effect of dapagliflozin on the primary outcome of cardiovascular death or hospitalization for heart failure among all patients, both those with HFrEF and those with HFpEF, again showed that event rates among patients treated with placebo were significantly higher in Black, compared with White patients, and this led to a difference in the number needed to treat to prevent one primary outcome event of 12 in Blacks and 17 in Whites, Jawad H. Butt, MD said in a talk at the meeting.

Although treatment with dapagliflozin reduced the rate of the primary outcome in this subgroup of patients from the DAPA-HF trial and the DELIVER trial by similar rates in Black and White patients, event rates were higher in the Black patients resulting in "greater benefit in absolute terms" for Black patients, explained Butt, a cardiologist at Rigshospitalet in Copenhagen.

But in contrast to the empagliflozin findings reported by Verma, the combined data from the dapagliflozin trials showed no suggestion of heterogeneity in the beneficial effect of dapagliflozin based on left ventricular ejection fraction. In the Black patients, for example, the relative benefit from dapagliflozin on the primary outcome was consistent across the full spectrum of patients with HFrEF and HFpEF.

EMPEROR-Reduced and EMPEROR-Preserved were sponsored by Boehringer Ingelheim and Lilly, the companies that jointly market empagliflozin (Jardiance). The DAPA-HF and DELIVER trials were sponsored by AstraZeneca, the company that markets dapagliflozin (Farxiga). Verma has received honoraria, research support, or both from AstraZeneca, Boehringer Ingelheim, and Lilly, and from numerous other companies. Butt has been a consultant to and received travel grants from AstraZeneca, honoraria from Novartis, and has been an adviser to Bayer.

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