Gagal Jantung Kongestif (CHF)

01Pathophysiology

Heart failure is fundamentally a syndrome in which the heart cannot pump enough blood to meet the metabolic demands of the body, or can only do so at the cost of elevated filling pressures. Understanding the two broad categories is essential because exam vignettes will test whether you can distinguish them.

Heart Failure with Reduced Ejection Fraction (HFrEF, EF <40%) is a problem of impaired contractility. The left ventricle cannot generate adequate forward stroke volume. The most common cause is myocardial infarction leading to loss of functional myocardium, but dilated cardiomyopathy from any etiology produces the same result. When stroke volume falls, the body activates the renin-angiotensin-aldosterone system (RAAS) and the sympathetic nervous system (SNS) as compensatory mechanisms. Angiotensin II causes vasoconstriction and aldosterone causes sodium and water retention, both of which increase preload and afterload. The SNS increases heart rate and contractility via catecholamines. In the short term these mechanisms maintain cardiac output, but chronically they are destructive: elevated afterload forces the ventricle to work harder, catecholamine excess is directly cardiotoxic, and volume overload leads to chamber dilation and progressive remodeling. This is why neurohormonal blockade (ACE inhibitors, beta-blockers, mineralocorticoid receptor antagonists) forms the backbone of therapy; you are interrupting the vicious cycle that worsens the disease.

Heart Failure with Preserved Ejection Fraction (HFpEF, EF ≥50%) is a problem of impaired relaxation and filling. The ventricle contracts normally but is stiff and noncompliant, so it cannot fill adequately at normal pressures. This results in elevated left atrial and pulmonary venous pressures, producing the same congestive symptoms (dyspnea, pulmonary edema) despite a normal EF. The classic patient is an elderly woman with longstanding hypertension, diabetes, and obesity. Chronic pressure overload from hypertension causes concentric left ventricular hypertrophy, which reduces chamber compliance. Recognize this on the exam: the patient has all the symptoms and signs of heart failure, but the echocardiogram shows a normal EF. That combination points to HFpEF.

The Frank-Starling mechanism is tested conceptually. In a healthy heart, increased preload stretches myocardial fibers, which increases the force of contraction and stroke volume. In HFrEF, the curve is flattened: increasing preload does not meaningfully improve stroke volume, and instead the excess volume backs up into the pulmonary and systemic venous circulation. This explains why patients develop pulmonary edema (left-sided backup) and peripheral edema with JVD (right-sided backup).

BNP (B-type natriuretic peptide) is released from ventricular myocytes in response to wall stress from volume and pressure overload. It acts as a counter-regulatory hormone, promoting natriuresis and vasodilation. Its clinical utility is as a biomarker: elevated levels confirm that the patient's dyspnea is cardiac in origin rather than pulmonary. This is the most commonly tested lab value in heart failure vignettes.

02Classification and Clinical Manifestation

NYHA Functional Classification

ACC/AHA Stages of Heart Failure

The key distinction the exam tests: NYHA class can fluctuate (a Class III patient may improve to Class II with treatment), but ACC/AHA stages only progress forward (a Stage C patient cannot return to Stage B). This is a commonly tested conceptual point.

Left-Sided vs. Right-Sided Failure

03Diagnostic Workup

The best initial test when a patient presents with dyspnea and you suspect heart failure is BNP or NT-proBNP. This is a rapid blood test that helps differentiate cardiac from pulmonary causes of shortness of breath. A BNP below 100 pg/mL makes heart failure very unlikely (high sensitivity for ruling out). A level above 400-500 pg/mL in the setting of appropriate symptoms makes heart failure highly probable. The "gray zone" between 100 and 400 requires clinical correlation. Important caveat: BNP can be falsely low in obese patients (adipose tissue expresses natriuretic peptide clearance receptors) and falsely elevated in renal failure (reduced clearance). These are commonly tested nuances.

A chest X-ray is obtained simultaneously and provides immediate information about congestion. The classic findings follow a predictable sequence as left atrial pressure rises: first you see cephalization (redistribution of blood flow to the upper lobes), then interstitial edema (Kerley B lines, peribronchial cuffing), then frank alveolar edema (bilateral fluffy opacities in a "bat-wing" distribution), and pleural effusions (bilateral, but if unilateral, more commonly right-sided).

The transthoracic echocardiogram is the single most important diagnostic study and should be considered the gold standard imaging test in heart failure evaluation. It tells you the ejection fraction (distinguishing HFrEF from HFpEF), reveals wall motion abnormalities suggesting prior ischemic injury, identifies valvular disease, measures chamber dimensions, and estimates pulmonary artery systolic pressure. Every newly diagnosed heart failure patient needs an echocardiogram. If the vignette describes a new patient with heart failure symptoms and asks for the "next best step" after initial labs and CXR, the answer is almost always echocardiogram.

An ECG is always obtained and may reveal the underlying cause: Q waves from prior MI, atrial fibrillation (both a cause and consequence of HF), left bundle branch block (important for determining candidacy for cardiac resynchronization therapy), or low-voltage QRS complexes (raising concern for infiltrative cardiomyopathy such as amyloidosis).

Cardiac catheterization is not routine but is indicated when ischemic etiology is suspected and revascularization may be beneficial, or when right heart catheterization is needed for hemodynamic assessment in diagnostically ambiguous cases or as part of transplant workup.

04Management and Treatment

Additional Agents

Acute Decompensated Heart Failure:
The patient who arrives to the emergency department in acute heart failure is typically volume overloaded, hypoxic, and tachycardic. The immediate priorities are:

1. Oxygen if hypoxemic; non-invasive positive pressure ventilation (BiPAP/CPAP) for respiratory distress or flash pulmonary edema

2. IV loop diuretics are the cornerstone of acute management. Furosemide 40 mg IV is a reasonable starting dose for diuretic-naive patients. For patients already on oral furosemide, the IV dose should be at least equal to or 2.5 times their home oral daily dose. The goal is aggressive diuresis to relieve congestion.

3. IV vasodilators (nitroglycerin or nitroprusside) are added if the patient is hypertensive. These reduce preload and afterload.

4. Inotropes (dobutamine, milrinone) are reserved for patients with cardiogenic shock or severe low-output states. They are NOT first-line and carry risk of arrhythmias.

5. Continue beta-blockers if the patient is already on them and is hemodynamically stable. If the patient is hypotensive or in cardiogenic shock, hold or reduce the dose but do not abruptly stop.

Chronic HFrEF Management:
The modern paradigm is to initiate all four foundational drug classes (ACEi/ARB/ARNI, beta-blocker, MRA, SGLT2 inhibitor) as early as possible and up-titrate to target doses. The classic teaching of sequential addition has shifted toward early, simultaneous initiation of all four when feasible. Each class independently reduces mortality.

If the patient remains symptomatic with $EF\le 35\mathrm{\%}EF\; \backslash leq\; 35\backslash \%$ after at least 3 months of guideline-directed medical therapy, they meet criteria for an ICD for primary prevention of sudden cardiac death. If they additionally have LBBB with QRS ≥150 ms, they are candidates for CRT (or CRT-D). These device-based therapies are critical exam topics.

For patients who remain refractory despite all medical and device therapies (ACC/AHA Stage D), advanced options include left ventricular assist device (LVAD) as bridge to transplant or destination therapy, and cardiac transplantation.

HFpEF Management:
This is often tested as a contrast to HFrEF. There is no proven mortality-reducing pharmacotherapy for HFpEF comparable to the four pillars of HFrEF, although SGLT2 inhibitors have now shown benefit (EMPEROR-Preserved, DELIVER trials) and represent the strongest evidence-based option. Treatment is focused on:

• Volume management with diuretics

• Blood pressure control

• Heart rate control if atrial fibrillation

• Treatment of comorbidities (obesity, diabetes, sleep apnea)

• SGLT2 inhibitors (dapagliflozin or empagliflozin)

05Differential Diagnosis and Distractors

06Traps and High-Yield Pearls

The single most common way students get heart failure questions wrong is failing to distinguish HFrEF from HFpEF before selecting treatment. The vignette will describe a patient with all the classic symptoms and signs of heart failure, and then the echocardiogram will show a normal ejection fraction. Students reflexively choose an ACE inhibitor or beta-blocker expecting mortality benefit, but in HFpEF the evidence base is different. If the EF is preserved, the answer is typically diuretics for symptom control and SGLT2 inhibitors as the strongest evidence-based option, along with aggressive comorbidity management. Always look at the EF before choosing therapy.

Another frequently tested trap involves the timing of ICD placement. The vignette may describe a patient with a brand-new diagnosis of HFrEF with an EF of 25%. Students want to immediately place an ICD for primary prevention. The correct answer is to first optimize medical therapy for at least 3 months and then reassess. Many patients will have EF improvement with medical therapy alone and may no longer meet ICD criteria. Similarly, after an acute MI, you must wait at least 40 days before considering an ICD.

Watch for questions that test contraindications to foundational therapies. A patient with bilateral renal artery stenosis or a history of angioedema with ACE inhibitors cannot receive an ACEi. A patient with $K^{+}>5.0mEq\mathrm{/}LK^+\; >\; 5.0\backslash \; mEq/L$ should not receive spironolactone. A pregnant patient cannot receive ACEi, ARB, or ARNI at any trimester. In African American patients with NYHA III-IV symptoms, remember that the combination of hydralazine plus isosorbide dinitrate added to standard therapy has a proven mortality benefit.

Beta-blocker selection is another trap. Only carvedilol, metoprolol succinate (extended-release), and bisoprolol are supported by mortality data in HFrEF. If the vignette offers metoprolol tartrate (short-acting) or atenolol as answer choices, those are wrong even though they are beta-blockers. Additionally, never start or up-titrate beta-blockers during an acute decompensation episode.

Finally, know that hyponatremia in heart failure (dilutional, from excess free water retention and neurohormonal activation) is a marker of poor prognosis and advanced disease. If the vignette describes a heart failure patient with a sodium of 128 mEq/L, this is not a primary sodium problem to correct with saline. It signals severe neurohormonal activation and the answer is typically fluid restriction and optimization of heart failure therapy.

The core competency being tested across heart failure questions is your ability to integrate the clinical presentation with objective data (EF on echo, BNP, CXR findings) to correctly classify the type of heart failure, select appropriate pharmacotherapy with awareness of contraindications, and apply device therapy criteria with correct timing.