The detection of myocardial ischemia in patients with preexisting left bundle branch block (LBBB) remains problematic. Pharmacologic hyperemia with dipyridamole is now used routinely in such patients for detection of significant coronary artery disease. Little data exists on the prognostic value of cardiac nuclear scintigraphy in patients with preexisting LBBB. The purpose of our study was to determine the prognostic value of cardiac nuclear scintigraphy in patients with preexisting LBBB.
Methods: Ninety-six patients with preexisting LBBB underwent perfusion imaging between July 1987 and June 1995. Thirty-seven underwent planar 201Tl imaging, and 59 underwent SPECT sestamibi imaging. Images were interpreted by consensus of two experienced observers and classified as normal, abnormal low risk and abnormal high risk. Outcomes measured were survival, cardiac and noncardiac death. The final study group included 43 women and 53 men, aged 42-83 (mean 66 +/- 9). Average follow-up was 3.4 +/- 2.1 yr.
Results: Of the 96 patients examined, 31 had normal scans, 39 had low-risk scans and 26 had high-risk scans. At the end of the study period, 27 patients with normal scans were still alive while 2 suffered cardiac death and 2 suffered noncardiac death. Of those with low-risk scans, 36 survived while 2 suffered cardiac death and 1 suffered noncardiac death. Finally, of those with high-risk scans, 17 survived while 8 suffered cardiac death and 1 suffered noncardiac death (chi-square test, p = 0.020).
Conclusion: Dipyridamole imaging is an important prognostic tool for predicting future cardiac events in patients with preexisting LBBB and aids in their risk stratification for coronary artery disease.