Evangelista Laura, Nai Fovino Luca, Saladini Francesca, Saladini Giorgio, Razzolini Renato, Mormino Gino Paolo, Al-Nahhas Adil, Rubello Domenico
Radiotherapy and Nuclear Medicine Unit, Medical Clinic IV, University of Padua, Padova, Italy.
Nucl Med Commun. 2012 May;33(5):491-7. doi: 10.1097/MNM.0b013e328350855a.
The abnormal left ventricular activation pattern in patients with a left bundle-branch block (LBBB) frequently induces myocardial perfusion defects, decreasing the specificity of noninvasive coronary-risk stratification with stress testing. We assessed the diagnostic and prognostic impact of gated single-photon emission computed tomography (SPECT) in low-risk patients with LBBB.
A total of 114 patients underwent dual-day protocol Tc-99m sestamibi gated SPECT and were divided into two subsets: without LBBB (group 1, n = 57) and with LBBB (group 2, n = 57). Sixty-eight (60%) patients had negative coronary angiography and 46 (40%) were at a low risk for coronary artery disease. The variables incorporating the extent and severity of perfusion defects were calculated: summed stress score, summed rest score and summed difference score, end-diastolic volume (EDV), end-systolic volume (ESV), and left ventricular ejection fraction. The mean variations in EDV and ESV were computed as follows: rest volume-poststress volume. Cardiac events were classified as major and minor.
Gated SPECT was positive in eight (14%) patients of group 1 and 33 (58%) patients of group 2 (P<0.001). The summed stress score was significantly higher in group 2 than in group 1 (4.7 ± 4.8 vs. 0.9 ± 1.8, P<0.001); similarly, EDV and ESV were significantly higher in LBBB patients (P<0.05 in both). The mean variation in EDV was -2.21 ml for group 1 and 1.32 ml for group 2 (P<0.05). After a mean follow-up period of 32 ± 19 months, cardiac events occurred in 22 (23%) patients, six of group 1 and 16 of group 2 (12 vs. 35%, P<0.01).
Functional and perfusion parameters obtained by gated SPECT are different between patients with and without LBBB. In LBBB patients, the decrease in EDV between rest and poststress could be considered an early marker of diastolic dysfunction that might anticipate left ventricular ejection fraction reduction and may have an impact on prognosis.
左束支传导阻滞（LBBB）患者的左心室激活模式异常常诱发心肌灌注缺损，降低了负荷试验对无创性冠状动脉风险分层的特异性。我们评估了门控单光子发射计算机断层扫描（SPECT）对LBBB低风险患者的诊断和预后影响。
共有114例患者接受了双日法锝-99m甲氧基异丁基异腈门控SPECT检查，并分为两个亚组：无LBBB组（第1组，n = 57）和有LBBB组（第2组，n = 57）。68例（60%）患者冠状动脉造影结果为阴性，46例（40%）患者患冠状动脉疾病风险较低。计算了反映灌注缺损范围和严重程度的变量：负荷总分、静息总分和差值总分、舒张末期容积（EDV）、收缩末期容积（ESV）和左心室射血分数。EDV和ESV的平均变化计算如下：静息容积-负荷后容积。心脏事件分为主要事件和次要事件。
第1组8例（14%）患者和第2组33例（58%）患者门控SPECT结果为阳性（P<0.001）。第2组的负荷总分显著高于第1组（4.7±4.8 vs. 0.9±1.8，P<0.001）；同样，LBBB患者的EDV和ESV也显著更高（两者均P<0.05）。第1组EDV的平均变化为-2.21 ml，第2组为1.32 ml（P<0.05）。平均随访32±19个月后，22例（23%）患者发生心脏事件，第1组6例，第2组16例（12% vs. 35%，P<0.01）。
门控SPECT获得的功能和灌注参数在有和无LBBB的患者之间存在差异。在LBBB患者中，静息和负荷后EDV的降低可被视为舒张功能障碍的早期标志物，这可能预示着左心室射血分数降低，并可能对预后产生影响。
