Prognostic Value of Vasodilator Myocardial Perfusion Imaging in Patients With Left Bundle-Branch Block

Abstract

Background-The prognostic value of tomographic myocardial perfusion imaging with dipyridamole or adenosine in patients with left bundle-branch block has not been established. Methods and Results-The study group consisted of 245 patients with left bundle-branch block who underwent tomographic (single photon emission tomography) myocardial perfusion imaging with thallium-201 (n=173) or technetium-99m sestamibi (n=72) and either dipyridamole (n=153) or adenosine (n=92) stress. Patients were prospectively classified into two groups. Patients were classified as "high risk" if they had (1) a large severe fixed defect (n=28), (2) a large reversible defect (n=36), or (3) cardiac enlargement and either increased pulmonary uptake (thallium) or a decreased resting ejection fraction (sestamibi) (n=20). The remaining 161 patients (66% of the study group) were at "low risk." Follow-up was 99% complete at 3 ±1.4 years. Three-year overall survival was 57% in the high-risk group compared with 87% in the low-risk group (P<.0001). Survival free of cardiac death/nonfatal myocardial infarction/cardiac transplantation was 55% in the high-risk group and 93% in the low-risk group (P<.0001). The presence of a high-risk scan had significant incremental prognostic value after adjustment for age, sex, diabetes, and previous myocardial infarction (P<.0001). Patients with a low-risk scan had an overall survival that was not significantly different from that of a US age-matched population (P=.86). Conclusions-Tomographic myocardial perfusion imaging with adenosine or dipyridamole stress provides important prognostic information in patients with left bundle-branch block, which is incremental to clinical assessment.

Patients with left bundle branch block pattern and high cardiac risk myocardial SPECT: does the current management suffice?

“…A normal-or low-risk MPS demonstrated a lower event rate than a high-risk MPS in these patients (Table 1) [18][19][20][21]27]. It is stressed that these figures are higher compared with low-and high-risk MPS in patients with a normal left ventricular activation [5,6,32].…”

“…Several reports studied the prognostic value of MPS in patients with LBBB [18,19,[26][27][28][29]31]. One report used the exercise characteristics for the prognostic value assessment and did not describe the results of the MPS.…”

“…The study characteristics are described in Table 1. Unlike earlier reports [18,19,27], wall motion analysis in conjunction with the perfusion results was used to define a low-risk MPS. This allows defining AARD.…”

“…Several reports defined a low-risk MPS in this patient population in the pre-gated SPECT era as completely normal scans, small to medium reversible or fixed defects, normal ventricular volumes and ejection fractions [18,20,21,27,28]. Since the introduction of gated SPECT it could be demonstrated that these low-risk MPS in an LBBB and RVA pacing population can be defined on the basis of combined perfusion and wall motion analysis.…”

“…Several authors claimed that these specific defects were small, located in well-defined regions and were classified as perfusion defects with a low risk for future cardiac events [18][19][20][21]. Addition of functional data from gated myocardial SPECT refined prognostic accuracy by enabling easy recognition of abnormal activation-related defects (AARD).…”