Is it appropriate to initiate an SGLT2 inhibitor in an 87-year-old patient after coronary artery bypass graft surgery?

Yes, initiate an SGLT2 inhibitor in this 87-year-old post-CABG patient, but wait until they are fully recovered, eating/drinking normally, and at least 24-48 hours post-surgery.

Timing and Safety Considerations Post-CABG

The critical issue is WHEN to start, not WHETHER to start. SGLT2 inhibitors should be withheld during surgery and the immediate perioperative period due to ketoacidosis risk, but then initiated once the patient has stabilized 1.

Perioperative Management

• Hold SGLT2i the day before and day of surgery 1, 2
• Do not restart until the patient is:
  • Eating and drinking normally
  • At least 24-48 hours post-surgery
  • Capillary ketones <0.6 mmol/L if still hospitalized 2

Why This Patient Should Receive SGLT2i

This 87-year-old post-CABG patient has established atherosclerotic cardiovascular disease (ASCVD), making them an ideal candidate 3. The evidence strongly supports SGLT2 inhibitor use in patients with:

• Established ASCVD (which CABG patients definitively have) 3
• Post-ACS/revascularization status 3, 4
• Heart failure (if present, regardless of ejection fraction) 1, 5
• Chronic kidney disease (if eGFR ≥20 mL/min/1.73 m²) 1

Age Is Not a Contraindication

Age 87 is NOT a contraindication to SGLT2 inhibitor therapy. Recent data shows no clinically meaningful differences in SGLT2 inhibitor tolerance in patients up to age 84, with only modest increased discontinuation risk at age ≥85 (21% increased risk) 6. The cardiovascular and renal protection benefits in this high-risk post-CABG population outweigh age-related concerns about tolerance.

Key Safety Data in Older Adults

• 1-year discontinuation rates: 34.9% in patients ≥85 years vs 25.8% in patients <65 years 6
• Most patients ≥85 years (65%) continue therapy successfully 6
• Closer follow-up is warranted, but age alone should not preclude initiation 6

Post-CABG Specific Evidence

Recent real-world data specifically in post-CABG patients is reassuring:

• SGLT2i use associated with lower 5-year mortality (13.6% vs 33.5%) in surgical AVR patients, many with concomitant CABG 7
• Reduced stroke risk (2.0% vs 19.3%) 7
• Lower risk of cardiac surgery-associated AKI in urgent/emergent CABG (risk ratio 0.63) 8
• No increased risk of postoperative diabetic ketoacidosis when appropriately managed 8

Critical Caveat: Ketoacidosis Risk

Multiple case reports document euglycemic DKA after cardiac surgery in patients on SGLT2i 9, 10, 11. However, these cases occurred when:

• SGLT2i was continued too close to surgery
• Patients were under surgical stress with inadequate monitoring
• None occurred when proper perioperative protocols were followed 8

Practical Implementation Algorithm

Step 1: Confirm Eligibility

• eGFR ≥20 mL/min/1.73 m² (can initiate; if eGFR ≥30 preferred for initial start) 1
• Not pregnant or breastfeeding 3
• No active diabetic ketoacidosis 12

Step 2: Assess Specific Indications (Post-CABG Patient Has Multiple)

• ✓ Established ASCVD (CABG = definitive ASCVD) 3
• Consider: Heart failure? (if LVEF ≤40% or HFpEF) 1, 5
• Consider: CKD with albuminuria? (if UACR ≥200 mg/g, Class 1A recommendation) 1
• Consider: Type 2 diabetes? 3

Step 3: Timing Post-Surgery

Wait until ALL of the following are met:

• Minimum 24-48 hours post-surgery 2
• Patient eating and drinking normally 2
• No nausea, vomiting, or prolonged fasting 1, 2
• If still hospitalized: capillary ketones <0.6 mmol/L 2
• Hemodynamically stable (no ongoing hypotension/hypovolemia) 1, 12

Step 4: Choose Agent and Dose

Select an SGLT2i with proven cardiovascular benefit:

• Empagliflozin 10 mg daily (can increase to 25 mg)
• Dapagliflozin 10 mg daily
• Canagliflozin 100 mg daily (avoid if history of amputation, severe PAD, or osteoporosis) 3, 12, 3

No dose titration required 3

Step 5: Adjust Concomitant Medications

• Reduce diuretics if volume depleted 1, 12
• Reduce insulin by 20% or sulfonylurea by 50% if glucose well-controlled or hypoglycemia history 12
• Continue ACE-I/ARB (SGLT2i tested on top of RAS inhibition) 1

Step 6: Patient Education (Critical)

Provide written sick-day rules 2:

• STOP SGLT2i during acute illness (nausea, vomiting, diarrhea, prolonged fasting) 1, 2
• Recognize DKA symptoms: nausea, vomiting, weakness (can occur with glucose 150-250 mg/dL) 12
• Maintain genital hygiene to prevent mycotic infections 1
• Monitor for hypotension symptoms (lightheadedness, orthostasis) 12

Step 7: Monitoring

• Renal function at 2-4 weeks (expect 3-5 mL/min/1.73 m² eGFR dip—this is normal and NOT a reason to stop) 1
• Home glucose monitoring first 4 weeks 12
• Closer follow-up given age ≥85 6
• No need to alter CKD monitoring frequency 1

Common Pitfalls to Avoid

1. Deferring initiation to outpatient setting: This exposes the patient to excess early post-discharge risk and the possibility of never receiving the medication due to clinical inertia 13

2. Stopping due to initial eGFR dip: The 3-5 mL/min/1.73 m² decline in first 4 weeks is expected, reversible, and NOT an indication to discontinue 1

3. Avoiding due to age: Age 87 alone is not a contraindication; benefits likely outweigh risks in this high-risk post-CABG patient 6

4. Starting too soon post-surgery: Must wait until eating/drinking normally to avoid ketoacidosis risk 2

5. Inadequate sick-day education: Failure to provide written instructions on when to hold SGLT2i during acute illness is a major safety gap 2

Special Considerations for This Patient

If Patient Has Heart Failure

Strong Class 1A recommendation regardless of ejection fraction or albuminuria 1, 5. Benefits accrue rapidly within days to weeks 13.

If Patient Has CKD

• eGFR ≥20 with UACR ≥200 mg/g: Class 1A recommendation 1
• eGFR 20-45 with UACR <200 mg/g: Class 2B recommendation (still reasonable) 1

If Patient Has Type 2 Diabetes

SGLT2i is first-line for CV protection in T2DM with ASCVD 3. Consider at hospital discharge with close outpatient follow-up 3.

Bottom Line

Initiate an SGLT2 inhibitor in this 87-year-old post-CABG patient once they are eating/drinking normally and at least 24-48 hours post-surgery. The cardiovascular and renal protection benefits are substantial in this high-risk population, age is not a contraindication, and post-CABG data is reassuring when proper perioperative protocols are followed. Provide written sick-day rules and ensure closer follow-up given advanced age.