Medical Subspecialties: Applying Disease-Modifying Therapy in Cardiology and Beyond
Medical Subspecialties tests focused knowledge in cardiology, endocrinology, nephrology, gastroenterology, neurology and related fields, with emphasis on when to refer and how to apply disease-modifying therapy. The examination favours common subspecialty scenarios and guideline-defined treatment thresholds over esoteric syndromes.
Core rules
- For heart failure with reduced ejection fraction (HFrEF), start all four guideline-directed pillars early: an ARNI (or ACE inhibitor/ARB), an evidence-based beta-blocker, a mineralocorticoid receptor antagonist and an SGLT2 inhibitor.
- Use loop diuretics for congestion, not as routine maintenance therapy in the absence of fluid overload.
- Check potassium and creatinine 1–2 weeks after starting or titrating an ACE inhibitor, ARNI or MRA.
- Treat iron deficiency in HFrEF: ferritin <100 ng/mL, or 100–299 ng/mL with transferrin saturation <20%, warrants consideration of intravenous iron.
- Avoid non-dihydropyridine calcium-channel blockers such as verapamil and diltiazem in HFrEF.
Worked example
A 60-year-old man with NYHA class II symptoms has LVEF 30%, eGFR 55 mL/min/1.73 m², potassium 4.3 mmol/L and BP 118/72 mmHg; he takes furosemide only. Start sacubitril/valsartan (or an ACE inhibitor if an ARNI is unavailable), carvedilol or bisoprolol, spironolactone 25 mg and dapagliflozin. Review renal function and potassium in 1–2 weeks, then titrate every 2–4 weeks as tolerated. Do not start an ACE inhibitor and an ARNI together; allow a 36-hour washout when switching.
Traps
- Waiting for full titration of one drug before starting the other three pillars.
- Missing iron deficiency because only haemoglobin was checked.
- Continuing verapamil or diltiazem in a patient with HFrEF.