Cardiac resynchronization therapy evaluated by myocardial scintigraphy with 99mTc-MIBI: changes in left ventricular uptake, dyssynchrony, and function.
OBJECTIVE
(99m)Tc-MIBI gated myocardial scintigraphy (GMS) evaluates myocyte integrity and perfusion, left ventricular (LV) dyssynchrony and function. Cardiac resynchronization therapy (CRT) may improve the clinical symptoms of heart failure (HF), but its benefits for LV function are less pronounced. We assessed whether changes in myocardial (99m)Tc-MIBI uptake after CRT are related to improvement in clinical symptoms, LV synchrony and performance, and whether GMS adds information for patient selection for CRT.


METHODS
A group of 30 patients with severe HF were prospectively studied before and 3 months after CRT. Variables analysed were HF functional class, QRS duration, LV ejection fraction (LVEF) by echocardiography, myocardial (99m)Tc-MIBI uptake, LV end-diastolic volume (EDV) and end-systolic volume (ESV), phase analysis LV dyssynchrony indices, and regional motion by GMS. After CRT, patients were divided into two groups according to improvement in LVEF: group 1 (12 patients) with increase in LVEF of 5 or more points, and group 2 (18 patients) without a significant increase.


RESULTS
After CRT, both groups showed a significant improvement in HF functional class, reduced QRS width and increased septal wall (99m)Tc-MIBI uptake. Only group 1 showed favourable changes in EDV, ESV, LV dyssynchrony indices, and regional motion. Before CRT, EDV, and ESV were lower in group 1 than in group 2. Anterior and inferior wall (99m)Tc-MIBI uptakes were higher in group 1 than in group 2 (p<0.05). EDV was the only independent predictor of an increase in LVEF (p=0.01). The optimal EDV cut-off point was 315 ml (sensitivity 89%, specificity 94%).


CONCLUSIONS
The evaluation of EDV by GMS added information on patient selection for CRT. After CRT, LVEF increase occurred in hearts less dilated and with more normal (99m)Tc-MIBI uptake.
Brandão
Simone C S
SC
Heart Institute (InCor), University of São Paulo Medical School, São Paulo, SP, Brazil. simonecordis@yahoo.com.br
Nishioka
Silvana A D
SA
Giorgi
Maria C P
MC
Chen
Ji
J
Abe
Rubens
R
Martinelli Filho
Martino
M
Hotta
Viviane T
VT
Vieira
Marcelo L
ML
Garcia
Ernest V
EV
Meneghetti
José C
JC
D000328:Adult; D000368:Aged; D005500:Follow-Up Studies; D006333:Heart Failure / Q000000981:diagnostic imaging* / Q000378:metabolism / Q000503:physiopathology / Q000628:therapy*; D006352:Heart Ventricles / Q000000981:diagnostic imaging / Q000378:metabolism* / Q000503:physiopathology*; D006801:Humans; D008297:Male; D008875:Middle Aged; D055414:Myocardial Perfusion Imaging; D017256:Technetium Tc 99m Sestamibi / Q000378:metabolism; D018487:Ventricular Dysfunction, Left / Q000000981:diagnostic imaging* / Q000378:metabolism*; D020257:Ventricular Remodeling
D017256:Technetium Tc 99m Sestamibi