QRS width does not reflect ventricular dyssynchrony in patients with heart failure

Abstract

The purpose of this study was to evaluate QRS width as an indication for cardiac resynchronization therapy. This study group consisted of 64 heart failure patients (51 men, age average 60.5 +/- 15.5 years) with a left ventricular ejection fraction (LVEF) of less than 35%. Patients were divided into two groups according to their QRS width; the wide QRS group (QRS width greater than or equal to 120 ms, 31 patients) and the narrow QRS group (QRS width less than 120 ms, 33 patients). The ventricular dyssynchrony (VD), i.e., the inter- and intraventricular dyssynchrony, of the two groups was compared. The correlation between QRS width and VD was evaluated in all patients. There were no significant differences between the wide and the narrow QRS groups concerning interventricular dyssynchrony [28.4 +/- 26.1 ms vs. 25.3 +/- 18.2 ms, not significant (NS)] or intraventricular dyssynchrony (99.0 +/- 43.8 ms vs. 109.0 +/- 56.6 ms, NS). Nor were there any differences in the LVEF (26.6 +/- 6.6% vs. 28.2 +/- 5.1%, NS), brain natriuretic peptide (BNP) (567.0 +/- 319.0 pg/ml vs. 390.0 +/- 375.8 pg/ml, NS), and New York Heart Association (NYHA) class (2.4 +/- 0.8 vs. 2.0 +/- 1.0, NS). QRS width did not correlate with interventricular (r = 0.026, NS) or intraventricular dyssynchrony (r = 0.052, NS). There were no differences in VD between the two groups based on differences in QRS width. There was also no correlation between QRS width and VD. It is suggested that QRS width is not an absolute indication for cardiac resynchronization therapy.

Diminished Left Ventricular Dyssynchrony and Impact of Resynchronization in Failing Hearts With Right Versus Left Bundle Branch Block

“…Single-site RV pacing generally produced similar improvements in global mechanical function and synchrony as with BiV pacing, and in some instances appeared superior to BiV stimulation. Interestingly, significant narrowing of the QRS complex with both RV-only and BiV pacing did not translate to a large functional improvement, supporting prior data showing lack of correlation between these parameters (17). Pacing combinations that produced LV functional benefit were also those that improved RV EF, suggesting that CRT with underlying RBBB may involve improvement of RV function, which assists in filling and function of the LV.…”

Cardiac Resynchronization Therapy (CRT)-Its History, Indication, Usefulness and Problems-

“…There are some patients with an indication for implantation who have a narrow QRS complex and no ventricular synchrony. 22) Such patients may not benefit from CRT, even though beneficial effects of CRT are expected under the current criteria. On the contrary, there has been a report of patients with a wide QRS complex with ventricular synchrony.…”

Cardiac Resynchronization Therapy (CRT) —Its History, Indication, Usefulness and Problems—

“…22) Such patients may not benefit from CRT, even though beneficial effects of CRT are expected under the current criteria. On the contrary, there has been a report of patients with a wide QRS complex with ventricular synchrony.…”