[TCT2007]高危患者过饱和氧治疗可以降低心肌梗死面积

　　AMIHOT II结果：心肌梗死后6小时内成功介入治疗的患者从过饱和氧（SS02）治疗中明显获益，SSO2能显著降低6小时内急性前壁心肌梗死高危患者的梗死面积。Gregg W Stone教授说这些患者并没有太多的治疗选择。AMIHOT II研究设计是AMIHOT I 的贝也斯级差模型分析。

　　SSO2 的提示

　　Stone教授解释说在经历了AMIHOT I 令人失望的结果之后，研究者意识到6个小时内的亚组患者可能有更大的获益，但是分析过程有一定的复杂性。该研究排除了极高危的患者，随机入选了301例急性前壁心肌梗死患者，根据2.8:1的比例将患者分为90min SSO2治疗组和标准治疗组。有效性定义为心肌梗死面积缩小，安全性定义为证实SSO2在30天不良事件上不劣于标准治疗。德国的Michael Haude询问是否更长的应用SSO2在挽救心肌上更有益处，而且对于完整评价该治疗还需要更长期随访。

　　SPECT 评价梗死面积

　　研究者采用Tc-99m Sestamibi SPECT测定梗死面积，发现SS02组梗死面积比对照组显著降低了6.5％（附图）。30天MACE 达到非劣性终点，SS02组是5.4%，对照组3.8%。Stone说SSO2组有比对照组更多并发症的趋势(22.5% vs. 12.7%)。Haude说MACE 和出血并发症应该引起关注，因为这会影响到长期结果，抵消梗死面积降低的好处。Stone说两组间输血率并无统计学差异。

　　Stone认为AMIHOT II也有几个不足，不足以发现死亡率上的差异，而最终1年随访结果将显示出梗死面积的降低是否能直接影响到生存或心力衰竭。

　　（武警总医院　韩玮　编译）

Supersaturated O2 Reduced Infarct Size in High-risk Patients

AMIHOT II results: MI patients treated withsuccessful angioplasty within 6 hours have greater benefit.

An infusion of supersaturated oxygen (SSO2) into the MI territory significantly reduced the infarct size in high-risk patients with acute anterior MI who had PCI within 6 hours of symptom onset.

“There really is no alternative for these patients,” said Gregg W. Stone, MD, chairman of the CardiovascularResearch Foundation.

Data from the AMIHOT II study was designed to be analyzed in conjunction with AMIHOT I findings by pooling the data via Bayesian hierarchical modeling.

Exposure to SSO2

Stone explained that after the disappointing results of AMIHOT I, investigators realized that the subset of
patients treated within 6 hours had a markedly reduced infarct size, but “you can’t look at a postoperative subset and claim success,” he said.

Excluding patients in very high-risk situations, the study randomized 301 patients with acute anterior MI to either 90 minutes of SSO2 or standard therapy on a 2.8:1 ratio. Efficacy was defined as the ability to demonstrate superiority with regard to a smaller infarct size. Safety was the ability to demonstrate noninferiority between SSO2 and standard therapy with regard to major adverse cardiac events (MACE) at 30 days.

Michael Haude, MD, of Lukaskrankkenhaus Neuss in Germany, questioned whether a longer exposure to
SSO2 would be even more beneficial for myocardial salvage and said that long-term follow-up is necessary for a complete evaluation of the therapy.

SPECT measured infarct size

Using Tc-99m Sestamibi SPECT to measure infarct size, investigators found that the SSO2 group had a
6.5% reduction in LV infarct size vs. the control group (Figure).

MACE at 30 days met the criteria for noninferiority, with a rate of 5.4% in the SSO2 group and 3.8% in controls.

Stone said there was a trend toward more complications at the access site within the SSO2 group compared with the standard care group (22.5% vs. 12.7%, respectively).

Haude said the event rate and other bleeding complications were of concern because they could impact
long-term outcomes and outweigh the reduction in infarct size. Stone said there was no statistical difference in transfusions between the groups.

The AMIHOT II trial had several limitations, Stone said. The study was underpowered for mortality, and
1-year follow-up will show whether the initial reduction in infarct size will have a direct impact on survival or heart failure rate, he said.

“There really is no alternative for these patients [with acute anterior MI who had PCI within 6 hours].” — Gregg W. Stone, MD