A 68-Year-Old Man with HFrEF, Hyperkalemia, and Two Missing Drug Classes
A 68-year-old man with ischemic cardiomyopathy (LVEF 28%) is seen 2 weeks after discharge for decompensated heart failure; he is now euvolemic. Medications are sacubitril/valsartan 24/26 mg twice daily, carvedilol 3.125 mg twice daily, and furosemide 40 mg daily. Blood pressure is 118/74 mmHg, heart rate 88/min, weight stable. Labs: eGFR 32 mL/min/1.73 m², potassium 5.2 mmol/L, sodium 136 mmol/L, hemoglobin 11.4 g/dL. He has paroxysmal atrial fibrillation and takes apixaban. He self-identifies as Black. For knee pain he takes ibuprofen 400 mg twice daily, and an outside clinician recently prescribed potassium chloride 20 mEq daily. He asks whether he can just keep his current regimen because he feels better.
1. Which guideline-directed medication classes are missing, and in what order would you add them given a potassium of 5.2 mmol/L and an eGFR of 32? Justify the sequence.
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Missing: an MRA and an SGLT2 inhibitor. Both reduce mortality and heart-failure hospitalization in HFrEF.
First, remove the reversible barriers (same visit): stop the ibuprofen (it worsens congestion, raises potassium, and risks AKI on an ARNI plus diuretic) and stop the potassium chloride supplement.
Start the SGLT2 inhibitor now - dapagliflozin 10 mg or empagliflozin 10 mg daily. Both can be initiated down to an eGFR of about 20–25, require no titration, cause a small expected eGFR dip (do not stop the drug for it), and modestly lower potassium. Benefit is independent of diabetes status, so there is no reason to delay it for the potassium level.
Then the MRA, once potassium is below 5.0. Spironolactone 12.5 mg daily (or eplerenone 25 mg) is appropriate at an eGFR of 32; the MRA carries the largest residual mortality benefit but is the agent least forgiving of hyperkalemia. Recheck potassium and creatinine in about 1 week. If potassium remains ≥5.0 after removing the supplement and NSAID, a potassium binder (patiromer or sodium zirconium cyclosilicate) is a reasonable way to enable the MRA rather than abandoning it.
Thereafter, uptitrate carvedilol and the ARNI toward target doses as blood pressure and potassium permit. Because he is self-identified Black with persistent symptoms, add hydralazine with isosorbide dinitrate once he is on optimized background therapy.
2. What laboratory and clinical monitoring would you arrange, and what findings would prompt you to hold or stop a drug?
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After the SGLT2 inhibitor: basic metabolic panel in 2–4 weeks. Expect a small, non-progressive rise in creatinine; that alone is not a reason to stop. Hold during acute illness with poor intake (sick-day rules) because of euglycemic ketoacidosis and volume-depletion risk, particularly with furosemide.
After starting the MRA: potassium and creatinine at roughly 1 week. Stop or hold the MRA for potassium above 5.5 mmol/L or a creatinine rise of more than 30%. Do not continue it through a diarrheal illness or a course of NSAIDs.
After each ARNI or beta-blocker uptitration: blood pressure, heart rate, potassium, and creatinine in 1–2 weeks; assess for orthostatic symptoms and congestion at each visit.
Clinically, ask about weight gain, orthopnea, and dyspnea at every visit, and about lightheadedness before each uptitration. Also monitor for hyperkalemia contributors that will otherwise be invisible: over-the-counter salt substitutes (potassium chloride), trimethoprim, and heparin, all of which raise potassium on top of an ARNI plus MRA.