Dapagliflozin: A Breakthrough Treatment for HFpEF

Dapagliflozin is the first drug to meaningfully reduce heart failure events in patients with heart failure with preserved ejection fraction, a condition that went decades without an effective treatment. In the landmark DELIVER trial, dapagliflozin cut the combined risk of worsening heart failure or cardiovascular death by about 18% compared with placebo over roughly two years of follow-up. That may sound modest in isolation, but for a disease where essentially every prior medication trial had failed, it represents a genuine shift in how cardiologists manage a condition that affects millions of people worldwide.

Why HFpEF Was Cardiology’s Biggest Unsolved Problem

Heart failure with preserved ejection fraction means the heart still squeezes with reasonable force, but it is stiff and does not fill properly. The result is fluid backup, shortness of breath, swollen legs, and deep fatigue, especially during exertion. HFpEF is the most common form of heart failure, and among elderly women it accounts for more than 80% of new cases.¹ Outcomes are grim: frequent hospitalizations, poor quality of life, and survival rates that approach those of the better-known form of heart failure where the heart muscle is weak.

For the other type of heart failure, where the pumping strength is reduced, doctors have a deep toolkit built on dozens of successful clinical trials: ACE inhibitors, beta-blockers, aldosterone antagonists, and more. HFpEF had none of that. Trial after trial came back negative, leaving clinicians with little more than diuretics and blood pressure control.² Part of the difficulty was the disease itself: HFpEF is not one condition but a cluster of overlapping problems involving the heart muscle, blood vessels, kidneys, fat tissue, and systemic inflammation. Animal models struggled to capture that complexity, which slowed the identification of drug targets.

What the DELIVER Trial Found

DELIVER enrolled over 6,200 patients with heart failure and an ejection fraction above 40%, randomly assigning them to dapagliflozin 10 mg once daily or placebo on top of their existing medications. Over a median follow-up of 2.3 years, the primary outcome, a composite of worsening heart failure or cardiovascular death, occurred in about 16% of the dapagliflozin group compared with roughly 20% in the placebo group. The hazard ratio was 0.82, and the result was highly statistically significant.³ Worsening heart failure specifically, meaning hospitalizations or urgent visits for fluid overload, dropped by about 21% with treatment.

The reduction in cardiovascular death alone did not reach statistical significance in DELIVER, with a hazard ratio of 0.88. That is not unusual: mortality endpoints in HFpEF trials are harder to move because the condition’s mortality is partly driven by non-cardiac causes like cancer and infection that no heart drug can address. The clearest benefit was in keeping patients out of the hospital and preventing episodes of worsening symptoms.

The benefits held up regardless of how symptomatic patients were at baseline. Whether someone was in a milder functional class or more severely limited, the reduction in the primary endpoint was virtually identical, with no meaningful interaction between symptom severity and treatment effect.⁴

Benefits Across the Full Range of Ejection Fractions

A common question is whether dapagliflozin works only in HFpEF or also across the broader spectrum of heart failure. A pooled analysis combining individual patient data from DELIVER (which tested dapagliflozin in patients with higher ejection fractions) and the earlier DAPA-HF trial (which tested it in patients with reduced ejection fractions) found that the drug reduced cardiovascular death and heart failure hospitalizations consistently across the entire ejection fraction range. There was no evidence that the benefit was stronger or weaker at any particular ejection fraction cutoff.⁵

This finding matters practically because ejection fraction is a measurement that can fluctuate over time. A patient whose number sits at 42% one month and 38% the next would historically have been caught in a bureaucratic gray zone between guidelines for different heart failure types. The pooled data suggest that the benefit of dapagliflozin is continuous rather than tied to arbitrary thresholds.

It Works Whether or Not You Have Diabetes

Dapagliflozin was originally developed as a diabetes drug. It lowers blood sugar by blocking a kidney protein that reabsorbs glucose, causing excess glucose to leave through the urine. That history raised a natural question: does the heart failure benefit depend on having diabetes?

A dedicated subgroup analysis from DELIVER divided patients into three glycemic categories: normal blood sugar, prediabetes, and type 2 diabetes. Dapagliflozin reduced the primary outcome to a similar extent in all three groups, with no interaction across the continuous range of hemoglobin A1c levels.⁶ An earlier, smaller trial of dapagliflozin in HFpEF had similarly found consistent results whether or not patients had diabetes.⁷ In other words, the glucose-lowering action is a side story. Something else about the drug drives the heart failure protection.

How Dapagliflozin Helps a Stiff Heart

Understanding exactly why dapagliflozin works in HFpEF is an active area of research, and the honest answer is that no single mechanism fully explains the results. But several pieces of the puzzle are coming into focus, and the hemodynamic data from invasive exercise studies have been particularly revealing.

A central problem in HFpEF is that filling pressures inside the heart spike during exertion, essentially flooding the lungs and causing breathlessness. The CAMEO-DAPA trial placed catheters in patients’ hearts and measured pressures at rest and during exercise before and after 24 weeks of treatment. Dapagliflozin lowered the pulmonary capillary wedge pressure, a key measure of that fluid backup, by about 3.5 mmHg at rest and nearly 6 mmHg at peak exercise compared with placebo.⁸ Those may sound like small numbers, but even modest reductions in filling pressure translate into noticeably easier breathing.

Part of the pressure relief comes from reducing plasma volume, the liquid portion of blood. Dapagliflozin shrank plasma volume by about 285 mL compared with placebo without significantly changing red blood cell volume or total blood volume. It also reduced what researchers call “stressed blood volume,” the fraction of blood that is actively pressurizing the veins, both at rest and during exercise, and it improved venous capacitance, meaning the veins could accommodate more blood at lower pressures.⁹ Think of it as relieving hydraulic pressure throughout the system, which unloads a heart that is struggling not because it is weak but because it is stiff.

The drug also appears to improve how the right side of the heart handles the pulmonary circulation. A secondary analysis of the CAMEO-DAPA data showed that dapagliflozin made the pulmonary arteries more compliant and less stiff, and improved the coupling between right-sided heart function and the resistance in the lungs during exercise.¹⁰ Right heart failure is a downstream consequence of longstanding HFpEF, and protecting the right ventricle may help prevent late-stage deterioration.

Beyond Fluid Shifts

Volume unloading is probably the fastest-acting benefit, but it likely is not the whole story. Dapagliflozin triggers changes in metabolism and inflammation that accumulate over weeks and months. In mouse models, the drug reduced cardiac fibrosis, the scarring that stiffens the heart, and single-cell analyses showed it reshaped gene expression in immune cells called macrophages, damping down the inflammatory signaling that activates scar-forming fibroblasts.¹¹ Whether the same anti-fibrotic effect occurs in human hearts at clinically used doses remains to be confirmed, but it offers a plausible explanation for why benefits in trials continued to accrue well beyond the first weeks of treatment.

Kidney and Metabolic Crosstalk

Heart failure and kidney disease feed off each other in a vicious cycle, and dapagliflozin intervenes at multiple points in that loop. Beyond its direct kidney effects on glucose and sodium handling, the drug influences a wide set of pathways including sympathetic nervous system activity, erythropoietin production, uric acid clearance, fat metabolism, and ketone body generation.¹² No single pathway dominates. The current thinking is that these drugs work through a constellation of modest, reinforcing effects rather than one dramatic mechanism, which ironically may be why they succeed where more targeted therapies have failed.

What Patients Actually Feel

Trial endpoints like hazard ratios and hospitalizations matter to researchers and health systems, but what patients care about most is whether they feel better day to day. The DELIVER trial measured this with a standardized questionnaire that captures heart failure symptoms, physical limitations, and social functioning. At eight months, patients taking dapagliflozin scored meaningfully higher across all domains compared with placebo. Fewer patients deteriorated, and more patients experienced clinically relevant improvements.¹³

A deeper look at individual questionnaire items showed that the biggest symptom improvements were in the frequency of leg swelling, the degree to which shortness of breath disturbed sleep, and the extent to which breathlessness limited desired activities.¹⁴ For anyone who has watched a family member with HFpEF struggle to climb stairs or wake up gasping at night, those particular improvements speak directly to the daily burden of the disease.

An earlier, smaller trial had already hinted at this. Twelve weeks of dapagliflozin significantly improved symptom scores, physical limitation scores, and six-minute walk distance by an average of about 20 meters compared with placebo, along with a modest reduction in body weight.⁷ Twenty meters may not sound like much, but in HFpEF patients who are profoundly deconditioned, it can represent the difference between walking to the mailbox comfortably and needing to stop and rest.

Safety, Especially in Older Adults

HFpEF is predominantly a disease of aging. The average DELIVER participant was in their early seventies, and a substantial number were older. This matters because older patients are more prone to dehydration, low blood pressure, and kidney injury, all potential concerns with a drug that causes the kidneys to excrete extra fluid and glucose.

Reassuringly, an age-stratified analysis of DELIVER found that although adverse events in general became more common with advancing age, there was no difference in predefined safety outcomes between dapagliflozin and placebo in any age category.¹⁵ A separate retrospective study focusing specifically on patients over 75 with HFpEF found no increase in serious kidney or metabolic events with dapagliflozin.¹⁶ Genital infections, which occur because sugar in the urine can feed yeast, remain the most characteristic side effect but are typically manageable with basic hygiene and, occasionally, antifungal treatment.

Starting Dapagliflozin in the Hospital

Most DELIVER participants began the drug as outpatients. A growing question has been whether it is safe and useful to start dapagliflozin sooner, during an acute heart failure hospitalization when patients are receiving intravenous diuretics and their kidney function is shifting rapidly.

The DAPA ACT HF-TIMI 68 trial tested exactly this. Dapagliflozin started during an acute admission was safe, though rates of symptomatic low blood pressure were slightly higher with the drug than placebo (about 3.6% vs. 2.2%), and mild worsening of kidney function was also modestly more common (roughly 5.9% vs. 4.7%).¹⁷ An earlier trial similarly found that early dapagliflozin during hospitalization was safe and appeared to enhance diuresis, even though it did not significantly improve a weight-based measure of diuretic efficiency.¹⁸ The practical upside of starting in-hospital is simple: patients leave already on the medication rather than depending on a follow-up appointment that may or may not happen.

Dapagliflozin Versus Empagliflozin

Empagliflozin, another drug in the same class, has its own positive trial in HFpEF called EMPEROR-Preserved. So a natural question is whether one drug is better than the other. The short answer is that available evidence points to a class effect rather than a meaningful difference between the two agents.

A retrospective cohort study comparing dapagliflozin and empagliflozin in HFpEF patients found similar efficacy and safety profiles, supporting the idea that the benefits are shared across the drug class.¹⁹ A separate analysis looking at long-term outcomes in heart failure patients after coronary procedures also found no significant differences in mortality, major adverse cardiac events, or hospitalization between the two drugs in HFpEF.²⁰ In practice, the choice between them often comes down to insurance formulary coverage and co-pay rather than clinical superiority.

Where Guidelines Stand Now

The accumulated evidence prompted the 2023 focused update of the European Society of Cardiology heart failure guidelines to recommend SGLT2 inhibitors (dapagliflozin or empagliflozin) across the entire ejection fraction spectrum, including HFpEF.²¹ Current treatment guidelines now consider an SGLT2 inhibitor optimal first-line therapy for HFpEF, with emerging evidence beginning to support additional agents like mineralocorticoid antagonists and GLP-1 receptor agonists in selected patients.²² For a condition that had no Class I recommended medication as recently as 2021, this represents a notable change in clinical practice.

Cost and Value

Breakthrough or not, a drug that patients cannot afford or that insurance will not cover does not change outcomes at the population level. In the United States, the full undiscounted monthly Medicare cost of dapagliflozin has been around $515, though rebates typically bring the real price closer to roughly half that. A cost-effectiveness analysis using pooled data from DELIVER and DAPA-HF estimated that dapagliflozin added about half a quality-adjusted life year over a patient’s remaining lifetime. At the full list price, the cost per quality-adjusted life year gained was about $85,500; at the rebated price, it dropped to about $40,000, well within what health economists typically consider high value.²³ Analyses from European health systems and from China’s national insurance perspective have similarly concluded that dapagliflozin is cost-effective for HFpEF.²⁴²⁵

The economics should continue to improve. AstraZeneca’s U.S. patent exclusivity for branded Farxiga (dapagliflozin) faces eventual expiration, and generic versions could dramatically reduce cost. Whether generic availability accelerates adoption among HFpEF patients who are currently undertreated remains to be seen, but the precedent from other cardiovascular generics suggests it could make a meaningful difference.

A Closer Look at Older Women With HFpEF

Because HFpEF disproportionately affects older women, how the drug performs in that specific group deserves attention. A single-center prospective study focusing on older female HFpEF patients found that dapagliflozin was associated with significant improvements in cardiac function, biomarker profiles, ventricular remodeling, and quality of life.²⁶ This is only one study, so the precise magnitude of benefit in this group should be interpreted cautiously. But it aligns with the subgroup analyses from the larger trials, none of which found that the drug’s effect was diluted in women or in the elderly. Given that older women represent the largest share of the HFpEF population, confirming that the drug works at least as well in them as in the broader trial cohort is clinically important.