QRS Fragmentation Is Not Associated with Poor Response to Cardiac Resynchronization Therapy

Methods: We reviewed the preimplant and follow-up echocardiograms in 233 patients undergoing the new implantation of a CRT device between December 2001 and November 2006. Patients were included if they had a pre-CRT ECG with appropriate filter settings (filter 0.16-100 or 0.16-150 Hz, 25 mm/s, 10 mm/mV), a left ventricular ejection fraction (LVEF) < 40%, and New York Heart Association class II-IV symptoms on standard medical therapy. The 12-lead electrocardiogram (ECG) was interpreted by two blinded reviewers for the presence of fQRS. Remodeling end points, including changes in LVEF and left ventricular end-diastolic (LVEDV) and systolic (LVESV) volumes, were compared between patients with and without contiguous fQRS, and an assessment of all-cause mortality was made. Results: Two hundred thirty-two patients met inclusion criteria, of which 50 demonstrated fQRS in contiguous leads. There was no difference in improvement in LVEF (%) (7.9 +/- 12.9 vs 6.8 +/- 11.0, P = 0.60) or reduction in LVEDV (mL) (-30.1 +/- 57.2 vs -15.7 +/- 47.6) or LVESV (mL) (-33.7 +/- 58.1 vs -22.7 +/- 50.6, P = 0.40) between patients with and without contiguous fQRS. At a mean follow-up of 4.4 +/- 1.9 years, there were a total of 89 deaths, 22 (44.0%) in patients with contiguous fQRS and 67 (36.8%) without (log rank P = 0.31). Conclusions: QRS fragmentation is not a predictor of progressive ventricular remodeling or mortality in heart failure patients undergoing CRT. Ann Noninvasive Electrocardiol 2011;16(2):165-171.