Improvement in cardiac sympathetic nerve activity in responders to resynchronization therapy.
OBJECTIVE
To assess changes in cardiac adrenergic activity with cardiac resynchronization therapy (CRT), and to investigate whether these changes are related to improvement in left ventricular ejection fraction (LVEF).


RESULTS
Sixteen patients (13 males, age 66 +/- 7 years) were studied at baseline and after > or =6 months of CRT (mean follow-up 9.2 +/- 3.2 months). LVEF was assessed by nuclear angiography. Responders were defined as patients showing > or =5% absolute increase in LVEF + improvement in > or =1 NYHA class + absence of heart failure hospitalization. Cardiac sympathetic nerve activity was studied by (123)I-metaiodobenzyl-guanidine ((123)I-MIBG) scintigraphy. Responders (n = 8) showed lower (123)I-MIBG washout at follow-up when compared with non-responders (P = 0.002), indicating lower cardiac sympathetic nerve activity. The decrease in (123)I-MIBG washout at follow-up when compared with baseline was only seen in the responder group (P = 0.036). There was a moderate correlation between increase in LVEF and decrease in (123)I-MIBG washout (r = 0.52, P = 0.04).


CONCLUSIONS
CRT induces a reduction in cardiac sympathetic nerve activity in responders, that parallels an improvement in LVEF, whereas non-responders do not show any significant changes.
Burri
Haran
H
Cardiology Service, University Hospital of Geneva, 23, Micheli-du-Crest, 1211 Geneva, Switzerland. haran.burri@hcuge.ch
Sunthorn
Henri
H
Somsen
Aernout
A
Fleury
Eric
E
Stettler
Carine
C
Shah
Dipen
D
Righetti
Alberto
A
D000368:Aged; D001281:Atrial Fibrillation / Q000628:therapy; D002304:Cardiac Pacing, Artificial / Q000379:methods*; D009202:Cardiomyopathies / Q000628:therapy; D005260:Female; D005500:Follow-Up Studies; D006321:Heart / Q000000981:diagnostic imaging / Q000294:innervation*; D006801:Humans; D008297:Male; D008875:Middle Aged; D010138:Pacemaker, Artificial; D011875:Radionuclide Angiography; D011877:Radionuclide Imaging; D013318:Stroke Volume / Q000502:physiology; D013564:Sympathetic Nervous System / Q000502:physiology*; D018487:Ventricular Dysfunction, Left / Q000503:physiopathology