A new simplified electrocardiographic score predicts clinical outcome in patients treated with CRT

Aims: Cardiac Resynchronization Therapy (CRT) reduces morbidity and mortality for patients with heart failure and wide QRS complex, but up to 1/3 of patients are "non-responders" to the therapy. This study examines the ability of a simple standard electrocardiogram (ECG)-based scoring system to predict clinical outcome. Methods and results: Four hundred and ninety-one consecutive patients with CRT-implants (79% males, mean age 71 years, LVEF 24%, 59% with ischemic cardiomyopathy, 83% in NYHA class III) were included from a single large volume centre. All patients met standard indications for CRT, and were followed for 3 years after CRT implantation. Three ECG parameters were measured on the post-implant ECG, and compared to pre-implantation measurements: QRS duration, time to intrinsicoid deflection onset (ID) in V1 lead, amplitude change in V1 lead. Each positive ECG variable was given a numerical value of 1 to create the score (ranging 0-3). Clinical outcome was assessed as a composite of all-cause death, left ventricular assist device implantation, cardiac transplantation and HF hospitalization. Event-free survival was predicted by shortening of QRS duration ≥20 ms (HR 0.66 [95% CI 0.48-0.90] P = 0.009), ≥50% decreased summed R + S amplitude in V1 lead (HR 0.67 [0.49-0.90] P = 0.009) and ≤40 msec ID time in lead V1 during pacing (HR 0.63 [0.46-0.86] P = 0.004). The total score was an independent predictor for both event-free survival (HR 0.65 [0.54-0.77] P < 0.001) and for ≥10% left ventricular ejection fraction improvement (OR 1.7 [1.3-2.3] P < 0.001). Conclusions: Composite data from 12-lead ECG during CRT-treatment can be used in a simple score to predict long-term clinical outcome.