β受体阻滞剂减少可卡因使用者心肌梗塞风险

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纽约(路透社健康快讯)2月15日-根据2月份<<急救医学年鉴>>报道，β受体阻滞剂可减少可卡因使用者心肌梗塞风险。“我们的研究结果提示，如果已知患者有潜在心脏疾病，完全有理由相信效果确切的β受体阻滞剂可以抗衡可卡因理论上且未经证实的α效应带来的损害，”来自纽约州布朗克斯区贾克比医疗中心的查尔斯-诺丁博士告诉路透社健康快讯。五年来，诺丁博士及同事针对入院后可卡因连续用药且尿液毒物学测试记录在案的患者，回顾性研究了β受体阻滞剂治疗对预防心肌梗塞或死亡发展的效应。363例患者中，有60例接受了一种β受体阻滞剂治疗。作者报告，33例接受β受体阻滞剂治疗的患者有2例（6.1%）发生心肌梗塞，而277例未接受β受体阻滞剂治疗的患者有72例（26.0％）发病。同时研究者指出，较对照组，β受体阻滞剂给药组患者患冠心病和收缩性心力衰竭的风险更高。所有接受β受体阻滞剂治疗的患者肌钙蛋白测试结果阴性，测试值不大于1.0，对照组只有57.9%符合此标准；前者无一例ST段抬高型心肌梗塞，而后者有9例。未接受β受体阻滞剂治疗的患者中，有4例住院期间再发心肌梗塞，β受体阻滞剂治疗组无一例发生；前者13例死于住院期间，后者1例。多变量模型分析显示，β受体阻滞剂显著减少患者心肌梗塞风险，但减少死亡风险无显著意义。“鉴于β受体阻滞剂被证实可以提高生存率，例如改善心肌梗塞后和收缩性心力衰竭的预后，我们应该鼓励医生考虑给予可卡因尿液毒物学测试阳性的患者β受体阻滞剂治疗，”诺丁博士说。“30年来，就这个严重问题一直没有重要临床结果文字报道，直到今天我们回顾了我们在贾克比医疗中心的工作，”诺丁博士补充。“我相信这是个另人发醒的经历－医生是多少容易把未经证实的理论信以为真啊！”在文章评论里，来自纽约市毒物中心的Robert S. Hoffman博士写道：“发现β-肾上腺素能拮抗剂对心血管有益处很难，因为这之中仅5％－6％有临床症状的患者会发作心肌梗塞，那些被纳入的住院死亡率接近零，那些被排除的就算他们继续使用可卡因也有极好的生存率。”（译者注：不知rule-in/rule-out指什么）“然而，”Hoffman博士总结，“当无益处和任何真实或感知风险放在一起进行权衡时，反对使用β-肾上腺素能拮抗剂在这种情况下仍然证据占优。根据此分析，作者呼吁进行可卡因使用者β-肾上腺素能拮抗剂治疗前瞻性试验看起来还不成熟，坦白地说还非常危险。”无论如何，Kalev Freeman博士（伯灵顿佛蒙特州立大学医学院）和James博士（波士顿大学医学分校）评论：“这些认为应撤销可卡因严重中毒患者β-肾上腺素能阻断治疗的理论和证据有明显的局限，应当进一步研究。”“在非严重可卡因中毒的急性冠脉综合征患者中进一步试验没有依据；无可卡因中毒的体征，仅因为可卡因尿检查结果阳性，临床医生对急性冠脉综合征患者给予推荐的内科治疗犹豫不决，可能延误病情。”“对无可卡因严重中毒仅可卡因尿检阳性的急性冠脉综合征患者，临床医生应该发挥β-肾上腺素能阻断剂的显著疗效，”Freeman和Feldman博士指出。“对可卡因急性中毒的患者，治疗方案＝β受体阻滞剂仍须进一步的研究和证据，这是没有争议的。”

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Beta-Blockers Reduce MI Risk After Cocaine Use

NEW YORK (Reuters Health) Feb 15 - Treatment with beta-blockers can reduce the risk of myocardial infarction after cocaine use, according to a report in the February Annals of Emergency Medicine.

\"Our results suggest that if you have a patient with known underlying heart disease, it is quite reasonable to assume that the known benefits of beta-blockers outweigh the theoretical and never-proven harms of the unopposed alpha effect (of cocaine),\" Dr. Charles Nordin from Jacobi Medical Center, Bronx, New York told Reuters Health.

Over a 5-year period, Dr. Nordin and colleagues retrospectively studied the effects of beta-blocker administration on the development of myocardial infarction or death after hospital admission of consecutive patients with cocaine use documented by urine toxicology. A beta-blocker was administered to 60 of 363 patients.

Two of 33 (6.1%) patients who received a beta-blocker developed a myocardial infarction, the authors report, compared with 72 of 277 patients (26.0%) who did not receive a beta-blocker.

Patients who received beta-blockers were at greater risk for coronary artery disease and systolic dysfunction congestive heart failure than those who did not receive beta-blockers, the investigators report.

None of the patients who received beta-blockers before a positive troponin test had a value greater than 1.0 (compared with 57.9% of patients who did not receive beta-blockers), and no patient given beta-blockers had an ST-elevation myocardial infarction (compared with 9 patients not given beta-blockers).

Four patients who did not receive beta-blockers had second myocardial infarctions during the hospitalization (compared with no patients treated with beta-blockers), and 13 patients who did not receive beta-blockers died during the hospitalization (compared with 1 patient treated with beta-blockers).

In multivariate models, beta-blocker use was associated with a significant reduction in the risk of myocardial infarction and a nonsignificant reduction in the risk of death.

\"We would encourage physicians to consider giving beta-blockers in patients with positive urine toxicology for cocaine in those situations where beta-blockers have been proven to increase survival, such as systolic dysfunction heart failure and post-myocardial infarction,\" Dr. Nordin said.

\"At no time in the past 30 years, up to the point where we reviewed our experience at Jacobi, have any significant clinical outcomes related to this important issue been documented,\" Dr. Nordin added. \"We believe that this serves as a cautionary tale in how easy it is as physicians to accept unproven theories as truth.\"

In an accompanying editorial, Dr. Robert S. Hoffman from New York City Poison Center writes: \"It is difficult to suggest a cardiovascular benefit for a beta-adrenergic antagonist in a disorder in which only 5% to 6% of patients with the presenting complaint will have a myocardial infarction, those who rule-in have an in-hospital mortality that approaches zero, and those who rule-out have an excellent survival even when they continue to use cocaine.\"

\"Thus,\" Dr. Hoffman concludes, \"when the lack of benefit is weighed against any real or perceived risk, the preponderance of evidence continues to speak against the use of beta-adrenergic antagonists in this setting. Given this analysis, the authors&#39; call for a prospective trial of beta-adrenergic antagonists in cocaine users seems not only premature but frankly quite dangerous.\"

However, Dr. Kalev Freeman from University of Vermont College of Medicine, Burlington, and Dr. James A. Feldman from Boston University School of Medicine argue: \"The theory and evidence for withholding beta-blockade in patients acutely intoxicated by cocaine have significant limitations and warrant further investigation.\"

\"There is no support for extending this practice to patients with acute coronary syndrome who are not acutely cocaine intoxicated, and clinicians who hesitate to administer the recommended medical therapy for acute coronary syndrome simply because of a positive urine test result for cocaine, without physical evidence of cocaine toxicity, may be doing their patients a disservice.\"

\"For patients with acute coronary syndrome and a positive urine cocaine test result, who are not acutely intoxicated, clinicians should pursue the apparent beneficial effect of beta-blockade,\" Dr. Freeman and Dr. Feldman conclude.

\"For patients with acute cocaine intoxication, the solution to the beta-blocker equation should be elucidated by further research and evidence, not opinion.\"