—钙化积分是死亡及非致命性心梗的强有力的预测因子
Noninvasive Imaging Improving for Detecting High-risk Plaque
Calcium score a strong predictor of death, nonfatal MI

    　无创性影像学检查显示动脉粥样硬化程度评估预后的价值远未清楚，但有证据表明可对危险程度进行鉴别。

　　尽管冠状动脉造影这类有创性的诊断技术广泛应用于以心肌梗死为首发表现的高危患者，但更多的为中危患者，无创性的影像学检查手段这类患者是更为理想的选择。

　　Mount Sinai医学院的Mario Garcia博士认为，如果体表动脉超声显示颈动脉内膜增厚，即使血管造影显示冠状动脉正常，也能提示IVUS结果阳性（图1）。

　　Garcia总结了以CT冠脉造影检查测得的冠状动脉钙化积分数据以及其预测心脏事件的价值。他认为，对于Framingham危险度积分大于16%的患者，冠状动脉钙化积分大于300是冠心病死亡及非致命性心梗的强有力的预测指标。

　　“钙化积分无法明确的问题之一是动脉粥样硬化的进展现状。由于它能清楚地告诉我们冠状动脉发生粥样硬化，通过相关因素分析，有时能提示我们病变的未来改变。但就目前而言，对脉管系统的预测知之甚少，”Garcia说。

　　SALTIRE试验显示，即使C-反应蛋白及低密度脂蛋白胆固醇可预测医学干预反应，但冠状动脉钙化积分仍无改变（图2）。

　　CT冠状动脉造影技术得到不断发展。屏气时间已从45秒降至6秒。现在一次扫描范围为64 x 0.6 mm，与以往4 x 1.0 mm相比，明显提高。对于64排CT而言，无诊断价值的扫描层面从30%降至8.7%。

　　Garcia说，有关CT诊断动脉粥样硬化负荷的疑难问题可能需3-5年时间才能得到答案，这些问题包括：CT检查能明确预后吗？它的性价比如何？筛选人群如何确定？检查频率如何？如何确定患者的危险程度？

　　（阜外心血管病医院　高立建　编译）

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Noninvasive Imaging Improving for Detecting High-risk Plaque
Calcium score a strong predictor of death, nonfatal MI.

The prognostic value of noninvasive imaging for profiling atherosclerotic burden is largely unknown, but there is evidence that it can identify risk.

Although invasive diagnostic techniques such as coronary angioplasty are used for patients at very high risk of first MI, a larger number of patients are at more moderate risk. Noninvasive imaging remains the more suit¬able option for these patients.

According to Mario Garcia, MD, of Mount Sinai School of Medicine, carotid intima media thickness, as measured by external carotid ultrasound, could predict IVUS-positive outcomes even when coronary angiography indicates coronary normality (Figure 1).

Garcia reviewed data measuring coronary artery calification (CAC) score with CTA and its value for predicting cardiac events. Among asymptomatic patients who have a Framingham risk score greater than 16%, a CAC score greater than 300 is a strong predictor of coronary death or nonfatal MI, he said.

“One thing that the calcium score is not telling us is the current status of atherosclerosis. It is very good at telling us the history of atherosclerosis in the coronaries, and therefore by association it can tell sometimes about the future. But the prediction about the status of the vasculature in the present is very poor,” he said.

The SALTIRE trial indicated that CAC score did not change even when CRP and LDL cholesterol responded predictably to medical therapy (Figure 2).

CTA technology continues to improve, with the breath-hold period now just 6 seconds, reduced from 45 seconds. The coverage for this imaging period is now 64 x 0.6 mm, up from the previous 4 x 1.0 mm, for the 64-segment MDCT; nonevaluable segments are now 8.7%, down from 30%.

Garcia said it may be 3 to 5 years before there are answers to several unresolved questions about the value of CT for diagnosing atherosclerotic burden, including: Can it change outcomes? Is it cost-effective? Who should be screened and how often? How can patients be identified who will benefit the most?