Cardiac resynchronization therapy may improve symptoms of congestive heart failure in patients without electrical or mechanical dyssynchrony.

Cardiac resynchronization therapy (CRT) has reportedly not been effective in the absence of electrical or mechanical dyssynchrony. We present six patients with severe left ventricular (LV) dilation, mitral regurgitation (MR), and non-ischaemic cardiomyopathy who underwent CRT. We assessed the effects of CRT on LV ejection fraction (EF), LV dimensions, mitral valve regurgitant fraction (RF), pulmonary arterial pressures (PAP), and serum levels of B-natriuretic peptide (BNP). All patients had severe LV dilation (>= 6.8 cm) and no electrical or mechanical dyssynchrony. All patients underwent CRT-D (with defibrillator) without complications. Average echocardiographic follow-up was 4.6 months. Mean LVEF increased significantly from 20.8 +/- 3.4 to 28.3 +/- 2.9% after CRT (P < 0.01). Mean LV end-diastolic dimension decreased significantly from 6.9 +/- 0.15 to 6.45 +/- 0.33 cm after CRT (P = 0.03); mean BNP serum level decreased from 1738 +/- 526 to 1040 +/- 768 pg/mL (P = 0.07). Baseline RF decreased from 45 +/- 12.2 to 20 +/- 10.9% after CRT-D (P = 0.009). Mean PAP decreased from 48.5 +/- 5.8 to 42.6 +/- 5.2 (P = 0.03). In five patients, New York Heart Association class symptoms improved by at least one level. No patients required assist devices or transplantation. One patient was hospitalized during follow-up. We describe six patients with severe LV dilation without evidence of electrical or mechanical dyssynchrony who improved with CRT, possibly due to improvement in MR.