ECG in Heart Failure

Cardiac failure is not a disease but a manifestation of underlying disease of the heart or the circulatory system.

Common causes of heart failure are coronary artery disease, cardiomyopathies, valvular heart disease and hypertensive heart disease.

A normal ECG is very unlikely in a patient of left ventricular dysfunction and hyas a negative predictive value of over 90% for presence of heart failure.

ECG abnormalities

  1. P wave abnormalities due to left atrial dilatation or bi atrial dilatation due to elevated end-diastolic left and right ventricular pressures.
  2. AV block of first or higher degress suggest underlying causes such as infiltrative cardiomyopathy.
  3. QRS complex duration prolongation
  4. Generalised low amplitude deflections of QRS complex are due to replacement of myocardium with fibrous tissue , pericardial effusion , hypothyroidism or amyloidosis.
  5. Left Ventricular Hypertrophy (LVH) is an independent predictor of a worse clinical outcome in patients with heart failure
  6. Q waves in precordial leads are an important predictor of low ejection fraction
  7. Absence of septal Q waves, which means it is an earliest manifestation of incomplete LBBB
  8. LBBB is generally associated with structural Heart disease in patients with heart failure and it usually indicates diffuse myocardial disease and fibrosis
  9. RBBB is not as common as that of LBBB in patients with heart failure
  10. ECG-CHF Triad
    Relatively low limb voltage in each of limb leads
    Relatively prominent QRS voltage in chest leads
    poor R wave progression ( R wave less than S wave in V1 through V4 )
  11. ST segment depression and T wave inversion may be seen and these changes are Non-Specific
  12. QT interval prolongation which is a predictor of worse outcome in patients with heart failure
  13. Sinus Tachycardia can occur due to catecholamine surge
  14. Ventricular tachycardia and Ventricular fibrillation are common terminal events

Examples of ECGs of patients with CHF:-

  • Ventricular Tachycardia in a patient of CHF

Electrocardiograph shows the absence of RS complexes in the precordial leads, a QS pattern in V6, and an R wave in aVR which means patient has VT.

  • LBBB in a patient of CHF

ECG of a CHF patient having LBBB.

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