Hammad Tarek A, Yousefzai Rayan, Venkatachalam Sridhar, Lowry Ashley, Gornik Heather L, Jaber Wael, Bartholomew John R, Kim Soo Hyun, Cerqueira Manuel, Gray Bruce H, Blackstone Eugene H, Shishehbor Mehdi H
Medicine Institute, Department of Hospital Medicine, Cleveland Clinic, Cleveland, OH, USA.
Heart and Vascular Institute, Department of Cardiovascular Medicine, Cleveland Clinic, Cleveland, OH, USA.
Vasc Med. 2016 Apr;21(2):113-9. doi: 10.1177/1358863X15623629. Epub 2016 Jan 21.
Peripheral artery disease (PAD) is associated with increased mortality and concomitant coronary artery disease (CAD). However, it is unclear whether uncovering the presence of functional coronary ischemia by single-photon emission computed tomography (SPECT) myocardial perfusion imaging (MPI) would further help stratifying that excess risk. From January 2000 to 2009, 4294 individuals underwent cardiac stress testing within 180 days of ankle-brachial index (ABI) measurements. Of these, 645 had PAD and SPECT MPI stress testing. Abnormal ABI was defined as ⩽ 0.9 or prior lower extremity arterial revascularization. Myocardial ischemic burden and total jeopardized myocardium were represented by the summed difference score (SDS) and summed stress score (SSS), respectively. Univariate and multivariable Cox proportional hazard analyses were used to study the impact of SDS and SSS on all-cause mortality. Additionally, using a hierarchical approach, we examined the step-wise addition of post-stress test coronary and lower extremity arterial revascularizations as time-varying covariates on outcomes. We found no significant difference in all-cause mortality between patients with ischemic myocardium (SDS > 0) and those without (SDS = 0) (adjusted HR: 0.94, 95% CI: 0.53-1.69; p = 0.84). Similarly, the presence of jeopardized myocardium (SSS > 0) did not have a significant impact on mortality (adjusted HR: 1.16, 95% CI: 0.67-2.00; p = 0.59). Moreover, adjustment for post-testing coronary and lower extremity arterial revascularizations did not affect our results. In conclusion, ischemic and jeopardized myocardia are not predictors of all-cause mortality in PAD; thus, SPECT MPI does not appear to be a useful risk stratification tool in these patients.
外周动脉疾病（PAD）与死亡率增加及合并冠状动脉疾病（CAD）相关。然而，通过单光子发射计算机断层扫描（SPECT）心肌灌注成像（MPI）来发现功能性冠状动脉缺血的存在是否会进一步有助于对这种额外风险进行分层尚不清楚。从2000年1月至2009年，4294例个体在踝臂指数（ABI）测量的180天内接受了心脏负荷试验。其中，645例进行了PAD和SPECT MPI负荷试验。异常ABI定义为≤0.9或既往有下肢动脉血运重建。心肌缺血负担和总的危险心肌分别用总差异评分（SDS）和总负荷评分（SSS）表示。采用单因素和多因素Cox比例风险分析来研究SDS和SSS对全因死亡率的影响。此外，我们采用分层方法，将负荷试验后冠状动脉和下肢动脉血运重建作为时变协变量逐步加入，以研究其对结局的影响。我们发现，有缺血心肌（SDS>0）的患者和无缺血心肌（SDS=0）的患者在全因死亡率上无显著差异（校正风险比：0.94，95%可信区间：0.53 - 1.69；p = 0.84）。同样，存在危险心肌（SSS>0）对死亡率也无显著影响（校正风险比：1.16，95%可信区间：0.67 - 2.00；p = 0.59）。此外，对试验后冠状动脉和下肢动脉血运重建进行校正并不影响我们的结果。总之，缺血和危险心肌并非PAD患者全因死亡率的预测因素；因此，SPECT MPI在这些患者中似乎并非有用的风险分层工具。
