Classification of Medical Therapy
For the treatment of chronic congestive heart failure (CHF), all medications are divided into two major categories.
Core drug classes include:
- Angiotensin-converting enzyme (ACE) inhibitors.
- Diuretics.
- $\beta$-blockers.
- Cardiac glycosides.
- Vasodilators.
Adjunctive medications are used in combination therapy to correct comorbid conditions. This group includes antiplatelet agents and anticoagulants (for thrombosis prophylaxis), antiarrhythmic drugs, as well as various vitamins and metabolic agents.
RAAS Blockers: ACE Inhibitors and ARBs
ACE inhibitors (Enalapril, Lisinopril, Fosinopril, Perindopril) are the cornerstone of treatment. They are indicated for all patients with reduced ejection fraction ($\le$ 35–40%). These drugs interrupt key pathways of disease progression by blocking angiotensin II synthesis. This leads to vasodilation (reduced afterload) and decreased aldosterone levels (reduced preload and fluid retention). The primary result of their use is a cardioprotective effect and proven mortality reduction.
Symptomatic improvement occurs slowly. Due to bradykinin accumulation, 5–15% of patients develop a dry cough that is refractory to antitussive medications. This is an absolute indication to discontinue ACE inhibitors and switch to angiotensin II receptor blockers (ARBs), such as Losartan. No clinical superiority of ARBs over ACE inhibitors has been demonstrated; they serve purely as a safe alternative.
Diuretic Therapy
Unlike ACE inhibitors, diuretics provide rapid relief within hours or days. They excrete excess fluid, reducing edema and body weight. It is important to remember that diuretic monotherapy is ineffective in CHF.
- Loop and thiazide diuretics (e.g., Furosemide). They rapidly eliminate water but can cause hypokalemia and hypomagnesemia. The dose is titrated while monitoring body weight (target weight loss rate: 0.5–1 kg/day). The starting dose of furosemide is typically 20–40 mg.
- Aldosterone antagonists (Spironolactone). Normally weak diuretics, they work powerfully in CHF due to secondary hyperaldosteronism. They conserve potassium and magnesium, reliably reducing mortality and the risk of repeated hospitalizations. They are frequently prescribed in combination with loop diuretics.
Beta-Blockers and the Hibernation Phenomenon
During myocardial hypertrophy, some cardiomyocytes suffer from hypoxia (vascular growth lags behind muscle growth) and enter a state of functional inactivity termed hibernation. $\beta$-blockers (Bisoprolol, Metoprolol, Carvedilol) restore the balance between myocardial oxygen demand and delivery. "Hibernating" cells awaken, and myocardial contractility paradoxically improves.
In addition, these drugs suppress renin secretion, decrease afterload, and protect the heart from the toxic effects of high catecholamine levels. They are strictly prescribed to patients with NYHA functional class II–III CHF and only after complete compensation of fluid and electrolyte balance. Non-selective agents (Propranolol) are undesirable due to the risk of increasing peripheral vascular resistance.
Cardiac Glycosides and Vasodilators
Digoxin is no longer considered a first-line drug and does not increase patient survival. Its main role is symptom stabilization, reduction of symptoms, and increased exercise tolerance. Modern approaches exclude rapid digitalization protocols: the drug is used in low doses (0.25 mg/day), maintaining plasma concentrations below 2 ng/mL, which minimizes the risk of adverse effects.
Vasodilators (Isosorbide dinitrate, Hydralazine) are used as an alternative to ACE inhibitors if the latter are contraindicated (e.g., in marked renal failure or severe hypotension). They reduce pre- and afterload, while hydralazine additionally exhibits antioxidant activity.