Effects of cardiac resynchronization therapy on myocardial perfusion reserve.
BACKGROUND
Cardiac resynchronization therapy (CRT) is a relatively new treatment strategy for patients with heart failure and mechanical asynchrony. Reported effects of CRT on regional myocardial blood flow (MBF) are conflicting, and effects on hyperemic MBF are scarce. The aim of the present study was to assess serial changes of MBF and MBF reserve in patients receiving a biventricular pacemaker.


RESULTS
Fourteen patients with heart failure (NYHA class III or IV; left ventricular ejection fraction <35%), QRS width >120 ms, and sinus rhythm were studied (mean age, 58+/-10 years; 8 men). MBF and hyperemic MBF were measured at baseline, 3 months after biventricular pacing (CRT on), and after cessation of pacing (CRT off) with PET and H2(15)O. CRT had no significant effect on resting MBF (baseline versus CRT on versus CRT off: 0.82+/-0.25 versus 0.69+/-0.24 versus 0.74+/-0.24 mL x min(-1) x mL(-1); P=NS). Hyperemic MBF increased during CRT (1.91+/-1.03 versus 2.66+/-1.66 versus 1.92+/-1.06 mL x min(-1) x mL(-1); P=0.01 by MANOVA), as did MBF reserve (2.25+/-1.00 versus 3.76+/-2.38 versus 2.49+/-0.94 mL x min(-1) x mL(-1); P=0.023). CRT (reversibly) resulted in a more homogeneous distribution of regional resting MBF as demonstrated by the septal-to-lateral ratio. The decrease in the ratio of left ventricular end-diastolic volume to left ventricular mass, as a reflection of wall stress, was related to the increase in hyperemic MBF (r=0.53, P<0.05). Left ventricular ejection fraction increased from 25+/-7% to 37+/-9% (P<0.01).


CONCLUSIONS
Resting MBF is unaltered by CRT despite an increase in left ventricular function. However, the distribution pattern of resting MBF becomes more homogeneous. Hyperemic MBF and consequently MBF reserve are enhanced by CRT.
Knaapen
Paul
P
Department of Cardiology, 6D Room 120, VU University Medical Center, De Boelelaan 1117, 1081 HV Amsterdam, The Netherlands. p.knaapen@vumc.nl
van Campen
Linda M C
LM
de Cock
Carel C
CC
Götte
Marco J W
MJ
Visser
Cees A
CA
Lammertsma
Adriaan A
AA
Visser
Frans C
FC
D000368:Aged; D002311:Cardiomyopathy, Dilated / Q000150:complications; D003326:Coronary Circulation; D005260:Female; D005500:Follow-Up Studies; D006333:Heart Failure / Q000000981:diagnostic imaging / Q000209:etiology / Q000503:physiopathology / Q000628:therapy*; D006352:Heart Ventricles / Q000473:pathology; D006801:Humans; D006940:Hyperemia / Q000503:physiopathology; D008297:Male; D008875:Middle Aged; D017202:Myocardial Ischemia / Q000150:complications; D009206:Myocardium; D009929:Organ Size; D010138:Pacemaker, Artificial; D013318:Stroke Volume; D014463:Ultrasonography