Empagliflozin or Dapagliflozin: The eGFR Threshold That Splits Them
A single patient with heart failure with preserved ejection fraction needs an SGLT2 inhibitor added to her regimen — but empagliflozin and dapagliflozin don't share the same renal-function floor, and her own kidney function is moving toward the one threshold that actually separates them.
V.H., a 74-year-old woman, has kept two hives behind her garage for eleven years, ever since a neighbor talked her into splitting a swarm rather than calling an exterminator. She still works them herself, though for the past year she's needed to sit on the overturned bucket she keeps nearby every few frames now, waiting for her breath to catch up before lifting the next box.
Her cardiologist diagnosed heart failure with preserved ejection fraction twenty-two months ago, after a hospitalization for volume overload that followed a bad flu season and a run of missed diuretic doses; her echocardiogram that admission showed an ejection fraction of 58%, and it hasn't moved much since. Fifteen years of type 2 diabetes and roughly a decade of hypertension had already been doing quiet work on her kidneys well before that admission. She'd been stable since then on losartan, atorvastatin, and torsemide, until a routine visit three weeks ago found her a few pounds above her dry weight and a little more short of breath at the hives than she'd been reporting — enough that her torsemide dose was increased on the spot.
A repeat basic metabolic panel drawn one week ago, meant only to confirm the diuretic change hadn't overshot, instead showed her estimated glomerular filtration rate at 26 mL/min/1.73m², down from 33 measured eight months earlier. Whether that window captured real, accelerating kidney disease or a hemodynamic dip from the diuretic increase itself isn't answerable from one number — but an SGLT2 inhibitor is overdue for her HFpEF regardless of which reading is closer to her true baseline, and the two agents under consideration don't share the same floor for how low that number is allowed to go before starting.
At the follow-up visit
Start empagliflozin today — not because dapagliflozin would fail her right now, but because I'd rather not be having this exact conversation again in three months if the next reading comes back at 23. EMPEROR-Preserved enrolled down to an eGFR of 20, and EMPA-KIDNEY, the dedicated renal-outcome trial for this agent, tested it specifically across that same low range. Dapagliflozin's own label draws its initiation floor five points higher, at 25. She clears that today, but only by one point, and eight months of trend doesn't inspire much confidence that one point holds.
If her renal function had been flat for years, I wouldn't be arguing this — either agent would be a genuinely equal choice. The whole case for empagliflozin here is the direction she's moving in, not anything wrong with dapagliflozin itself.
I'd hold off choosing between them until we know what that 26 actually means. Her torsemide dose went up three weeks ago for volume she was carrying, and a diuretic-driven contraction in effective circulating volume drops estimated GFR through the same afferent-arteriolar mechanism we spend so much time explaining away when it happens after starting an SGLT2 inhibitor itself. It isn't evidence of new nephron loss — it's hemodynamics catching up to a dose change.
One reading two weeks into that adjustment, set against a value from eight months ago, isn't enough to separate a real decline from a volume-status artifact. I'm not arguing against the durability point if the trend turns out to be real — only against deciding which drug is right before we know whether there's a real trend to be right about.
Agreed on rechecking before we commit to anything. But if it comes back reassuring, let's not lose sight of what that actually means: she's eligible for dapagliflozin today, and in DELIVER — dapagliflozin's own outcome trial in heart failure with preserved ejection fraction — the benefit held up as well in patients her age as anyone younger, and the label already tells us what to do if her renal function keeps sliding after we start it — continue, don't stop. The durability argument matters less once you notice the drug she'd be on doesn't need her eGFR to stay above 25 forever, only on the day we write the prescription.
Agreed unanimously: hold torsemide at its current dose, no further diuretic change today; repeat a basic metabolic panel in one to two weeks, once she's had time to equilibrate clear of the recent dose change; start whichever SGLT2 inhibitor the group settles on once that number is in hand, rather than today.
Not agreed, and left as two live defaults rather than a resolved plan:
The Primary Care Physician's default is dapagliflozin — she is eligible, and DELIVER's population matches her directly. The Cardiologist's default is still empagliflozin, for the renal margin. Both agents remain on the table.
The question resolves itself — dapagliflozin is no longer initiable, and empagliflozin is the only agent left standing. No real disagreement survives this branch.
The Cardiologist and the Primary Care Physician left the visit still disagreeing about which agent they'd choose if both remain on the table — a disagreement that only survives if the confirmatory number comes back reassuring.