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This is a clinician-written, evidence-based summary aligned to the USMLE Step 2 CK Content Outline. It is intended for medical students preparing for USMLE Step 2 CK. Management reflects current ACC/AHA, USPSTF, and APA guidelines. Always cross-reference with UpToDate, institutional protocols, and clinical judgment.
The Bottom Line
- Heart failure = congestion +/- low cardiac output from structural/functional cardiac impairment
- Classify by LVEF: HFrEF (<=40%), HFmrEF (41-49%), HFpEF (>=50%)
- BNP >100 pg/mL or NT-proBNP >300 pg/mL supports diagnosis; normal levels rule out HF
- HFrEF GDMT four pillars: ARNi + beta-blocker + MRA + SGLT2 inhibitor — initiate all early
- Acute decompensated HF: IV furosemide first-line; vasodilators if hypertensive; inotropes only for cardiogenic shock
Overview
Heart failure is a complex clinical syndrome resulting from any structural or functional cardiac disorder that impairs ventricular filling or ejection of blood. The 2022 AHA/ACC/HFSA Guideline classifies HF into four stages (A-D) and three LVEF categories: HFrEF (reduced, LVEF <=40%), HFmrEF (mildly reduced, 41-49%), and HFpEF (preserved, >=50%). Robust mortality-reducing evidence exists primarily for HFrEF, though SGLT2 inhibitors now show benefit across the entire EF spectrum.
Epidemiology
Heart failure affects approximately 6.7 million American adults with ~960,000 new cases annually. Prevalence increases with age: ~1-2% overall, >10% over age 70. The most common etiology is ischemic heart disease (~50%), followed by hypertension, valvular disease, and cardiomyopathy. Five-year mortality remains ~50%. HF is the leading cause of hospitalization in Medicare patients. African Americans have disproportionately higher incidence and worse outcomes.
Clinical Features
Symptoms
Dyspnea on exertion, progressing to orthopnea and paroxysmal nocturnal dyspnea
Fatigue and exercise intolerance
Bilateral lower extremity edema (pitting)
Weight gain from fluid retention (>2 lb/day or >5 lb/week)
Acute pulmonary edema: sudden severe dyspnea, pink frothy sputum
Bendopnea (dyspnea bending forward — elevated filling pressures)
Signs
Elevated JVP (>8 cm H2O)
Bibasilar crackles (may be absent in chronic compensated HF)
S3 gallop (volume overload — specific for HF in adults)
S4 gallop (non-compliant ventricle, diastolic dysfunction)
Displaced PMI (LV dilation)
Hepatojugular reflux, hepatomegaly, ascites (right-sided HF)
Cool, mottled extremities (low cardiac output / cardiogenic shock)
Investigations
First-line
BNP / NT-proBNPBNP >100 or NT-proBNP >300 supports HF. Age-adjusted NT-proBNP cutoffs: >450 (<50y), >900 (50-75y), >1800 (>75y). BNP falsely low in obesity. Sacubitril increases BNP — use NT-proBNP if on ARNi
Transthoracic echocardiogramEssential: LVEF, chamber dimensions, wall motion, valvular function, diastolic parameters, RVSP
Basic labsCBC, BMP (Cr, BUN, K+, Na+), LFTs, TSH, iron studies (ferritin + TSAT), HbA1c
ECGQ waves (prior MI), LVH, AF, LBBB (QRS >=150 ms = CRT candidate)
Second-line
Chest X-rayCardiomegaly, cephalization, Kerley B lines, pleural effusions
Cardiac MRIGold standard LVEF; late gadolinium enhancement for scar; infiltrative disease
Specialist
Right heart catheterizationDirect hemodynamics (PCWP, CI, SVR) for refractory HF or transplant evaluation
Coronary angiographyIf ischemic etiology suspected and revascularization considered
1
HFrEF GDMT (four pillars)
- Pillar 1: ARNi (sacubitril-valsartan) preferred — 36h washout from ACEi required. If intolerant: ACEi or ARB
- Pillar 2: Beta-blocker: carvedilol, metoprolol succinate (NOT tartrate), or bisoprolol
- Pillar 3: MRA: spironolactone or eplerenone 25-50 mg (K+ <5.0, eGFR >30)
- Pillar 4: SGLT2i: dapagliflozin 10 mg or empagliflozin 10 mg — benefit independent of diabetes
- Initiate all four early; rapid sequence initiation now recommended over sequential titration
- African American NYHA III-IV: add hydralazine + isosorbide dinitrate (A-HeFT)
2
HFpEF
- SGLT2 inhibitor (dapagliflozin or empagliflozin) — Class 2a (EMPEROR-Preserved, DELIVER)
- Diuretics for congestion (symptomatic, no mortality benefit)
- Treat underlying: HTN, AF, CAD, obesity
- GLP-1 RA for obese HFpEF (semaglutide — STEP-HFpEF)
3
Acute decompensated HF
- IV furosemide bolus or infusion; add metolazone for diuretic resistance
- Warm + wet (most common): diuretics + vasodilators (IV NTG if hypertensive)
- Cold + wet (cardiogenic shock): inotropes (dobutamine/milrinone) +/- mechanical support
- BiPAP for pulmonary edema before intubation
- Continue GDMT as tolerated; do NOT d/c beta-blocker unless shock
4
Device therapy
- ICD: LVEF <=35% after >=3 months GDMT, NYHA II-III, survival >1 year
- CRT: LVEF <=35% + LBBB + QRS >=150 ms + NYHA II-IV (best with LBBB)
- Transplant: refractory Stage D
- LVAD: bridge to transplant or destination therapy
5
General measures
- Na+ <1500 mg/day; fluid restrict 1.5-2 L/day if hyponatremic
- Daily weights — seek care if >3 lb gain in 24 h
- Cardiac rehab; vaccination (flu, pneumococcal, COVID)
- Avoid NSAIDs, non-DHP CCBs (in HFrEF), thiazolidinediones
Complications
- Cardiogenic shock: CI <2.2, PCWP >18, hypotension — mortality ~40-50%
- Arrhythmias: AF (~50% of HF), VT/VF (leading cause of SCD in HFrEF)
- Cardiorenal syndrome: Worsening renal function from low CO or venous congestion
- Hepatic congestion: Cardiac cirrhosis from chronic right HF
- Hyponatremia: Dilutional (ADH excess) — poor prognosis
- Cardiac cachexia: Unintentional weight loss — poor prognosis
USMLE Step 2 CK Exam Tips
- 1BNP is the best initial test to distinguish cardiac from pulmonary dyspnea
- 2Four pillars of HFrEF GDMT: ARNi + BB + MRA + SGLT2i — start all early, do not wait to titrate sequentially
- 3Sacubitril-valsartan requires 36h washout from ACEi (angioedema risk)
- 4S3 in an adult = volume overload, specific for HF. S4 = diastolic dysfunction
- 5Tolerate up to 30% Cr rise on ACEi before stopping
- 6African American NYHA III-IV: add hydralazine + isosorbide dinitrate to GDMT
- 7CRT: most effective with LBBB + QRS >=150 ms — NOT for narrow QRS
- 8Metoprolol SUCCINATE (not tartrate) for HF — only succinate, carvedilol, bisoprolol have mortality data
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