达到≥10代谢当量的运动负荷预示着诱发缺血的风险极低：心肌灌注成像有作用吗？
Achieving an exercise workload of > or = 10 metabolic equivalents predicts a very low risk of inducible ischemia: does myocardial perfusion imaging have a role?
作者信息
Bourque Jamieson M, Holland Benjamin H, Watson Denny D, Beller George A
机构信息
Cardiovascular Division and the Cardiovascular Imaging Center, Department of Internal Medicine, University of Virginia Health System, Charlottesville, VA 22908, USA.
出版信息
J Am Coll Cardiol. 2009 Aug 4;54(6):538-45. doi: 10.1016/j.jacc.2009.04.042.
OBJECTIVES
We sought to identify prospectively the prevalence of significant ischemia (> or =10% of the left ventricle [LV]) on exercise single-photon emission computed tomography (SPECT) imaging relative to workload achieved in consecutive patients referred for myocardial perfusion imaging (MPI).
BACKGROUND
High exercise capacity is a strong predictor of a good prognosis, and the role of MPI in patients achieving high workloads is questionable.
METHODS
Prospective analysis was performed on 1,056 consecutive patients who underwent quantitative exercise gated (99m)Tc-SPECT MPI, of whom 974 attained > or =85% of their maximum age-predicted heart rate. These patients were further divided on the basis of attained exercise workload (<7, 7 to 9, or > or =10 metabolic equivalents [METs]) and were compared for exercise test and imaging outcomes, particularly the prevalence of > or =10% LV ischemia. Individuals reaching > or =10 METs but <85% maximum age-predicted heart rate were also assessed.
RESULTS
Of these 974 subjects, 473 (48.6%) achieved > or =10 METs. This subgroup had a very low prevalence of significant ischemia (2 of 473, 0.4%). Those attaining <7 METs had an 18-fold higher prevalence (7.1%, p < 0.001). Of the 430 patients reaching > or =10 METs without exercise ST-segment depression, none had > or =10% LV ischemia. In contrast, the prevalence of > or =10% LV ischemia was highest in the patients achieving <10 METs with ST-segment depression (14 of 70, 19.4%).
CONCLUSIONS
In this referral cohort of patients with an intermediate-to-high clinical risk of coronary artery disease, achieving > or =10 METs with no ischemic ST-segment depression was associated with a 0% prevalence of significant ischemia. Elimination of MPI in such patients, who represented 31% (430 of 1,396) of all patients undergoing exercise SPECT in this laboratory, could provide substantial cost-savings.
目的
我们试图前瞻性地确定在运动单光子发射计算机断层扫描（SPECT）成像中，相对于连续接受心肌灌注成像（MPI）检查的患者所达到的工作量，显著缺血（左心室[LV]≥10%）的患病率。
背景
高运动能力是预后良好的有力预测指标，而MPI在达到高工作量的患者中的作用存在疑问。
方法
对1056例连续接受定量运动门控（99m）Tc - SPECT MPI检查的患者进行前瞻性分析，其中974例达到或超过其最大年龄预测心率的85%。这些患者根据所达到的运动工作量（<7、7至9或≥10代谢当量[METs]）进一步分组，并比较运动试验和成像结果，特别是≥10%左心室缺血的患病率。还对达到≥10 METs但未达到最大年龄预测心率85%的个体进行了评估。
结果
在这974名受试者中，473例（48.6%）达到或超过10 METs。该亚组中显著缺血的患病率非常低（473例中有2例，0.4%）。达到<7 METs的患者患病率高18倍（7.1%，p<0.001）。在430例达到或超过10 METs且无运动ST段压低的患者中，无人有≥10%左心室缺血。相比之下，在达到<10 METs且有ST段压低的患者中，≥10%左心室缺血的患病率最高（70例中有14例，19.4%）。
结论
在这个具有中度至高度冠状动脉疾病临床风险的转诊患者队列中，达到≥10 METs且无缺血性ST段压低与显著缺血患病率为0%相关。在本实验室接受运动SPECT检查的所有患者中，这类患者占31%（1396例中的430例），取消对他们的MPI检查可节省大量成本。
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