Management of chf

MANAGEMENT OF CHF

• Aim of treatment for compensated/chronic CHF:
  • Decreasing work of heart – By decreasing preload & afterload.
  • Decreasing mortality – By reversing cardiac remodeling.
• Major drugs used: Vasodilators, ACE inhibitors, ARBs, beta blockers & aldosterone antagonists.

1. Vasodilators:

MOA:

• Acts by reducing preload (venodilators), afterload (arteriolar dilators) or both (combined arteriolar & venodilators).

Important drugs:

• Nitrates: 
  • Preferentially dilate veins (venodilator) & reduces preload.
• Hydralazine & minoxidil:
  • Primarily arteriolar dilators (arteriolar dilators) & reduces afterload.
  • Preferred in forward failure with low cardiac index (central venous pressure).

Note:  Calcium channel blockers contraindicated in CHF – Due to reflex sympathetic activation (nifedipine) & direct cardio-depressant action (verapamil & diltiazem) –> increasing mortality.

• ACE inhibitors, angiotensin 2 receptor blockers (ARBs), nitroprusside & alpha blockers:
  • Reduces both preload & afterload
• ACE inhibitors & angiotensin receptor blockers (ARBs):
  • Indicated for all CHF grades unless contraindicated specifically.
  • Decreases mortality – 
    • By prevention & reversal of cardiac remodeling due to decreased aldosterone activation (final mediator for remodeling).
• Combination of hydralazine & isosorbide dinitrate:
  • Decreases mortality.
  • Other vasodilators do not prolong survival in CHF.

2. Aldosterone antagonists:

• Mainly potassium-sparing diuretics – Spironolactone & epleronone.
• Reduces mortality (at doses lower than diuretic doses) – By antagonizing aldosterone effect(reversal of remodeling). Tolerance prevented by adding thiazides.

3. Beta-blockers:

• Contra-indicated due to their negative ionotropic action – Needs careful usage.
• Important drugs: 
  • Carvedilol (most commonly used) –>metoprolol → bisoprolol.
• Drug effects:
  • Increases longevity of CHF patients.
  • Causes renin release stimulating RAAS & increased aldosterone.
  • Antagonizes RAAS pathway → Causing reversal of remodeling.
• Indication: 
  • Mild to moderate heart failure (NYHA class II & III) with dilated cardiomyopathy.
• Contraindication: 
  • Absolutely in decompensated heart failure – As it reduces cardiac contractility.
  • Started at very low doses à gradually increased for maximum benefit.

4. Ivabradine:

• Funny current blocker used in angina pectoris.
• European guidelines recommend for CHF patients with heart rate >70 bpm with ejection fraction < 35%, symptomatic despite treatment with beta blockers, ACE inhibitors & aldosterone antagonists.
• Not FDA approved for this indication.
• Decreases myocardial oxygen demand by causing bradycardia.

5. Vasopeptidase inhibitors:

• MOA: Inhibits two enzymes, ACE & NEP.
• Drugs included: Omapatrilat & sampatrilat.
• Drug effects: 
  • Possess all ACE inhibitors effects.
  • Causes natriuresis – Due to increased BNP & decreased metabolism by NEP inhibition.
• Use: Oral treatment of chronic CHF.
• Adverse effect: Angioedema (major).