Background: Cardiac resynchronisation therapy (CRT) has beneficial effects on cardiac function, exercise tolerance, symptoms, and prognosis. Coronary blood flow impairment has been observed in patients with non-ischaemic dilated cardiomyopathy (DCM) despite angiographically normal coronary arteries. No data are available on coronary blood flow and coronary flow reserve (CFR) measured by intracoronary Doppler in different coronary arteries in patients with DCM and left bundle branch block (LBBB) before and during treatment with CRT.
Aim: Thus, the major aim of our study was to assess the effect of CRT on coronary blood flow in patients with non-ischaemic DCM and to compare coronary blood flow and CFR measured in the 3 major coronary arteries (left anterior descending [LAD], left circumflex [LCX], and right coronary artery [RCA]).
Methods: Twenty one patients with DCM and LBBB (mean left ventricular ejection fraction 26 ± 7%, 5 females, mean age 57.8 ± 8.1 years) were studied. Average peak velocity, diastolic/systolic velocity ratio and CFR were measured using intracoronary Doppler before and 6-9 months after implantation of CRT-D or CRT-P.
Results: In patients with a clinical improvement (71.4%), CFR increased in LAD. CFR measured in LCX and RCA did not improve either in the overall study group or in patients with a clinical improvement. The observed increase in CFR in LAD correlated only with reduction of QRS duration.
Conclusions: In non-ischaemic DCM, CFR is reduced only in LAD. A significant improvement of CFR in LAD after CRT correlates with reduction of QRS duration.