Atypical P-wave morphology at baseline was associated with superior response to CRT at 1 year with a larger reduction in left ventricular end-diastolic volume ( -23 12 % vs. -20 11 % , P = 0.009 ) , left ventricular end-systolic volume ( -36 16 % vs. -31 16 % , P = 0.006 ) , and left atrial volume ( -31 12 % vs. -27 12 % , P = 0.005 ) , with a slightly larger absolute increase in left ventricular ejection fraction ( LVEF ) ( 12 5 % vs. 11 5 % , P = 0.009 ) .