ECG Findings in Congestive Heart Failure

Key Diagnostic Principles

A normal ECG combined with normal natriuretic peptide levels essentially excludes heart failure as the cause of symptoms, according to the European Heart Journal 1, 3
A completely normal ECG makes heart failure, especially with left ventricular systolic dysfunction, highly unlikely and should prompt reconsideration of the diagnosis, as stated by the European Heart Journal 1, 2

Atrial fibrillation/flutter is one of the most frequent arrhythmias, occurring in approximately 13-14% of heart failure patients and primarily predicting cardiovascular death rather than heart failure hospitalization, as reported by the European Heart Journal 5
QRS prolongation ≥120 ms occurs in approximately 16% of patients and indicates electrical dyssynchrony, potentially identifying candidates for cardiac resynchronization therapy, according to the European Heart Journal 2, 5
Left bundle branch block appears in 6% of patients and is associated with increased risk of heart failure hospitalization, as stated by the European Heart Journal 5
Low QRS voltage combined with ventricular wall thickening creates a diagnostic paradox suggesting infiltrative cardiomyopathy and warrants cardiac MRI evaluation, as recommended by the European Heart Journal 5, 6

Atrial fibrillation/flutter requires rate control, anticoagulation assessment using CHA₂DS₂-VASc score, and consideration of rhythm control with amiodarone, as suggested by the European Heart Journal 7
QRS ≥120 ms with LBBB morphology identifies candidates for cardiac resynchronization therapy (CRT-P or CRT-D) after echocardiographic confirmation of dyssynchrony, according to the European Heart Journal 5

Do not assume a diagnosis of heart failure is correct if the ECG is completely normal—this combination has <10% probability of systolic heart failure and warrants diagnostic reconsideration, as stated by the European Heart Journal 1, 2, 4
Do not overlook low voltage ECG with ventricular thickening on imaging—this paradoxical finding strongly suggests infiltrative cardiomyopathy requiring cardiac MRI for definitive diagnosis, as recommended by the European Heart Journal 5, 6
Do not attribute all ECG changes to heart failure itself—systematically evaluate for reversible causes including electrolyte abnormalities, drug toxicity, ischemia, thyroid dysfunction, and systemic diseases, as suggested by the European Heart Journal 5