RESUMO
To determine the prognostic value of myocardial perfusion scintigraphy with dipyridamole stress in patients with preexisting left bundle-branch block [LBBB] with or without chest pain. Seventy-six patients, mean age 53 +/- 10 years, with preexisting LBBB underwent technetium-99m-sestamibi perfusion imaging with dipyridamole infusion protocol [0.56 mg/kg]. Stress and rest single photon emission computed tomography [SPECT] images were interpreted by consensus of 2 experienced nuclear medicine physicians and classified as low-risk scans [normal myocardial perfusion scan, small reversible/small fixed defect] and high-risk scans [large, severe, fixed or reversible defect and dilated left ventricle cavity]. The patients were followed up for 24 +/- 8 months and occurrences of hard cardiac events [infarction or cardiac death] were noted. Of the 76 patients, 52 [68%] had low-risk scans and the remaining 24 [32%] had high-risk scans. In the low-risk group, 1 [1.9%] cardiac death and 2 [3.8%] cases of nonfatal myocardial infarction occurred, while in the high-risk group, 5 [20.8%] suffered cardiac death, and 3 [12.5%] nonfatal myocardial infarction. Overall survival rate was 98.1% in the low-risk group compared with 79.2% in the high-risk group with a significant difference of p = 0.034. Negative predictive value of normal myocardial perfusion scintigraphy for the occurrence of death was 100%. No significant difference in survival rate among patients with or without chest pain [p = 0.31] was observed. Myocardial perfusion imaging with dipyridamole provided important prognostic information in patients with LBBB; it was useful in stratifying the patients according to cardiovascular morbidity and mortality, and would thus allow the clinician to provide early treatment especially in the high-risk category