GATED-SPECT Myocardial scintigraphy in left bundle branch block: a study in patients with and without coronary artery disease

Falcão Andrea MGM, Moffa PJ, Chalela WA, Ferreira BA, Uchida AH, Pastore CA, Kreling JC, Oliveira CG, Meneghetti JC, Soares Jr J, Ramires JF.
Heart Institute (InCor), University of  Sao Paulo Medical School
Av. Dr Eneas de Carvalho Aguiar, 44 – 05403-000 - São Paulo, SP - Brazil

Abstract: 46 patients with LBBB without and with CAD confirmed by angiography, underwent to GATED SPECT scintigraphy, with 2 stress tests, according to a dipyridamole stress test and Bruce treadmill exercise test. Myocardial perfusion, wall motility, wall thickening  and left ventricle ejection fraction were the parameters analyzed by the GATED SPECT.  In conclusion, we observed that only wall thickening was able to differenciate between LBBB with and without coronary disease, when we considered the anterior and septal myocardial segments.

INTRODUCTION

Myocardial perfusion scintigraphy is a non-invasive method helpful for evaluating the coronary heart disease. In left bundle branch block (LBBB), the myocardial scintigraphy frequently reveals septal abnormalities in the absence of coronary artery disease (CAD) and gives rise to "false-positive" results in patients with suspected CAD. The purpose of this study was to assess the diagnostic role of ECG-GATED SPECT in patients with complete LBBB, with and without known CAD.

METHODS

This study included 46 patients (pts), 29 women (63%), with mean age 63.8 +11.6yr, divided into 02 groups: Group 1 (n=21 pts) with LBBB and CAD confirmed by angiography, and Group 2 (n=25 pts) with LBBB and normal coronariography. All patients underwent to a 02 stress tests according to a dipyridamole (DIP) stress test protocol and maximal Bruce treadmill exercise test (ET). Myocardial perfusion, wall motility and wall thickening were analyzed in anterior, septal, inferior, lateral and apical segments, by semi-quantitative methods and the left ventricle ejection fraction (LVEF) were calculated automatically from the ECG-GATED SPECT.

RESULTS

The table 1 shows the comparative analysis between the groups 1 and 2, for the parameters analyzed in the myocardial segments.

Table 1	anterior	septal	inferior	lateral	apical
ETP	P=0.58	P=0.65	P=0.0001	P=0.08	P=0.08
DIPP	P=0.42	P=0.75	P=0.0001	P=0.08	P=0.08
ETM	P=0.19	P=0.83	P=0.01	P=0.43	P=0.15
DIPM	P=0.12	P=0.93	P=0.01	P=0.43	P=0.07
ETT	P=0.31	P=0.05	P=0.01	P=1.00	P=0.31
DIPT	P=0.31	P=0.05	P=0.01	P=1.00	P=0.31

ETP= exercise test perfusion; DIPP=dipyridamole perfusion; ETM= exercise test motility, DIPM= dipyridamole motility;
ETT= exercise test thickening; DIPT= dipyridamole thickening.

The rest, exercise and DIP LVEF did not show statistically significant differences, between the groups 1 and 2 (p>0.05).

CONCLUSION

In the anterior and septal segments, only septal wall thickening was able to differenciate between LBBB with and without CAD.