AimsIn CARE-HF, cardiac resynchronization therapy (CRT) lowered morbidity and mortality in patients with moderate to severe heart failure. We examined whether baseline and follow-up electrocardiographic characteristics might predict long-term outcome. Methods and resultsCARE-HF randomly assigned 409 patients to medical therapy (MT) plus CRT, and 404 patients to MT alone. Electrocardiographic measurements were made at baseline during sinus rhythm, and at 3 months during paced or spontaneous rhythm depending on treatment assignment. Favourable outcome was defined as freedom from death, urgent transplantation, or cardiovascular hospitalization. Among patients assigned to CRT, 39% had unfavourable outcomes including 55 deaths. By single variable analysis, (i) prolonged PR interval, left QRS axis (but not QRS duration), and left bundle branch block (BBB) at baseline, and (ii) heart rate, PR, and QRS duration at 3 months predicted unfavourable outcome. By multiple variable analysis, treatment assignment (P ¼ 0.0001), PR (P ¼ 0.0004), and right BBB (P , 0.00013) at baseline predicted outcome, whereas baseline JTc and QRS duration at 3 months predicted all-cause mortality and heart failure hospitalization (P ¼ 0.0071). ConclusionIn CARE-HF, QRS duration at baseline did not predict outcome, but QRS at 3 months was a predictor by single variable analysis. Patients with prolonged PR interval and the 5% of patients with right BBB had a particularly high event rate.--

A more favourable outcome of CRT with regard to LV reverse remodelling and the composite of time to death or first HF hospitalization was observed when the LV lead tip was implanted in the lateral wall, away from the apex, while the position of the RV lead tip was indifferent. The long-term change in QRS duration was significantly associated with the position of the LV lead tip. ClinicalTrials.gov Identifier: NCT00271154.

Transvenous CRT system implantation, using a CS lead designed for long-term LV pacing, was safe and reliable. As implanting centres become more experienced, this success rate is expected to increase further.

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The MR of the dilated cardiomyopathy is multifactorial. Our data suggest that analysing only LV geometry and mitral orifice is insufficient to correctly describe functional MR determinant. LV contractility and dyssynchrony are essential too.