Current guidelines support the use of cardiac resynchronization therapy (CRT) in patients with heart failure and a prolonged QRS interval (≥120 ms); however, tissue Doppler imaging has shown ...

However, in the subgroup with a narrow QRS duration, there were no significant changes in the indices of left ventricular remodeling or in the NYHA functional class and there was a significant ...

These maneuvers were all consistent with atypical, slow-slow atrioventricular nodal reentrant tachycardia (AVNRT ... demonstrating a narrow QRS, with a similarly short S-A interval.