Heart Failure for OPRA: Four-Pillar Therapy, HFrEF vs HFpEF and MCQs

HFrEF, HFmrEF and HFpEF — why the label changes the treatment

Heart failure with reduced ejection fraction (HFrEF, LVEF ≤40%) has a large evidence base for disease-modifying drug therapy that actually improves survival. Heart failure with mildly reduced ejection fraction (HFmrEF, LVEF 41–49%) sits between the two, and management often resembles HFrEF's four-pillar approach where the patient is a suitable candidate — it isn't a separate third treatment pathway so much as a reminder that patients aren't simply "HFrEF or HFpEF." Heart failure with preserved ejection fraction (HFpEF, LVEF ≥50%) has a much thinner evidence base for mortality benefit, and management leans more heavily on treating congestion and comorbidities (hypertension, atrial fibrillation, obesity) than on the full four-pillar combination. An OPRA stem that specifies ejection fraction is telling you which treatment paradigm applies — don't assume every patient is either HFrEF or HFpEF with nothing in between.

The four pillars of HFrEF therapy

• ACE inhibitor or ARB, with sacubitril-valsartan (an ARNI) preferred in many symptomatic HFrEF patients who remain suitable candidates after ACE inhibitor washout — reduces the harmful effects of the renin-angiotensin system on cardiac remodelling.
• Beta blocker (specifically bisoprolol, carvedilol or metoprolol succinate extended-release — not just any beta blocker, and not the immediate-release metoprolol tartrate formulation) — reduces the harmful effects of sustained sympathetic activation.
• Mineralocorticoid receptor antagonist (spironolactone or eplerenone) — reduces aldosterone-driven fibrosis and remodelling. Generally avoided in significant hyperkalaemia or severe renal impairment, given the drug class's own potassium-raising effect.
• SGLT2 inhibitor (e.g. dapagliflozin, empagliflozin) — now part of first-line HFrEF therapy regardless of diabetes status, an evidence base that postdates the drug class's original diabetes indication.

Monitoring after initiation or dose increases

• Potassium — particularly with an ACE inhibitor/ARB combined with an MRA, since both raise potassium independently.
• Renal function — creatinine/eGFR, especially around ACE inhibitor/ARB and MRA titration.
• Blood pressure — symptomatic hypotension can limit up-titration of the RAS-blocking pillars and the beta blocker.
• Weight and fluid status — a practical day-to-day proxy for congestion, often tracked by the patient themselves.

Practise this topic

Recognising which pillar is missing from a patient's regimen — and why a specific beta blocker matters, not just "a" beta blocker — is exactly the reasoning OPRA tests. Practise more Therapeutics and Cardiovascular OPRA questions with ClinicalStem's OPRA question bank.

Diuretics manage symptoms, they don't modify disease

Loop diuretics (e.g. furosemide) relieve congestion — breathlessness, peripheral oedema — and are titrated to the patient's fluid status, not to a fixed dose. They are not one of the four pillars because they haven't been shown to improve survival on their own; they're for symptom control, used alongside (not instead of) the four disease-modifying pillars. A stem describing worsening dyspnoea and oedema in a HFrEF patient is usually testing diuretic dose adjustment, not pillar selection — the two are separate decisions addressing separate problems. If congestion persists despite otherwise-optimal four-pillar therapy, the loop diuretic dose is increased rather than stopping a disease-modifying pillar, unless a genuine contraindication to that pillar has developed.

Building the four-pillar regimen in practice

All four pillars are typically introduced (at low doses, then up-titrated as tolerated) rather than fully optimising one class before starting the next — waiting to maximise an ACE inhibitor dose before starting a beta blocker delays the mortality benefit of the pillars not yet started. Blood pressure, renal function and potassium guide the pace of up-titration, particularly with the ACE inhibitor/ARB and MRA combination (both can raise potassium).

Switching to an ARNI: the 36-hour washout

When switching a patient from an ACE inhibitor to sacubitril-valsartan (an ARNI), a 36-hour washout after the last ACE inhibitor dose is required before starting the ARNI, because both drug classes affect bradykinin breakdown — overlapping them significantly raises the risk of angioedema. No washout is required switching from an ARB to an ARNI. This specific interval is a frequently tested detail, not just a general "leave a gap" principle.

Is heart failure treated the same way as hypertension, since they share drug classes?

No — despite overlapping drug classes, the treatment goals differ. In HFrEF, ACE inhibitors, specific beta blockers, MRAs and SGLT2 inhibitors are combined as disease-modifying "pillars" regardless of blood pressure, rather than being chosen primarily to lower blood pressure as in hypertension.

Are diuretics one of the four pillars of heart failure therapy?

No — diuretics (typically a loop diuretic) manage congestion and symptoms, but they haven't been shown to independently improve survival the way the four pillars have. They're used alongside the four pillars, not as a substitute for any of them.

Why are some beta blockers avoided in heart failure but others aren't?

The mortality benefit in HFrEF has only been demonstrated for bisoprolol, carvedilol, and metoprolol succinate (extended-release) — other beta blockers and the immediate-release metoprolol tartrate formulation don't carry the same evidence base, even though beta blockade as a mechanism is broadly similar.

Is HFmrEF treated the same way as HFrEF?

Management often resembles HFrEF's four-pillar approach where the patient is a suitable candidate, but HFmrEF (LVEF 41–49%) isn't identical to HFrEF — it's a distinct category between HFrEF and HFpEF, and the evidence base for each pillar in this specific range is still less extensive than in HFrEF itself.