Empagliflozin (SGLT2 inhibitor) reduces hospitalisation for heart failure with reduced EF (HFrEF) independent of its glucose-lowering effect. The proposed cardioprotective mechanism involves:
- A Direct blockade of cardiac sodium-proton (NHE1) exchanger reducing intracellular sodium and calcium overload in cardiomyocytes ✓
- B Marked reduction in LDL-cholesterol due to stimulation of hepatic LDL receptor expression
- C RAAS inhibition via prevention of glomerulotubular balance feedback signals
- D Increased cardiac contractility via phosphodiesterase-3 inhibition in the myocardium
Explanation
Multiple mechanisms have been proposed for SGLT2 inhibitor cardiac benefits beyond glycaemia. The most supported direct myocardial mechanism is inhibition of the cardiac NHE1 (Na+/H+ exchanger), which SGLT2 inhibitors inhibit off-target. Reduced intracellular Na+ reduces reverse-mode NCX (Na+/Ca2+ exchanger) activity, lowering intracellular Ca2+ overload, reducing diastolic dysfunction and arrhythmogenic potential. Additional mechanisms include diuretic/natriuretic effects (reducing preload), erythropoietin stimulation, and a shift toward ketone body utilisation as a more oxygen-efficient cardiac fuel (the 'fuel switch' hypothesis).
Reference: KD Tripathi, Essentials of Medical Pharmacology, 8th ed.
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