Bata Iqbal, Armstrong Paul W, Westerhout Cynthia M, Travers Andrew, Sookram Sunil, Caine Edward, Christenson James, Welsh Robert C
Dalhousie University, Halifax, Nova Scotia, Canada.
Can J Cardiol. 2009 Aug;25(8):463-8. doi: 10.1016/s0828-282x(09)70118-7.
Recent research and contemporary ST elevation myocardial infarction guidelines emphasize the importance of prompt reperfusion and have redefined the traditional time to treatment metric to include prehospital paramedical staff as the point of first medical contact. However, an important knowledge gap exists relating to data systematically addressing the impact of arrival at the hospital by ambulance and the delays inherent in transfer from a community hospital to tertiary centres for percutaneous coronary intervention (PCI).
The Which Early ST Elevation Myocardial Infarction Therapy (WEST) study initiated treatment at the point of first medical contact, including prehospital contact. Patients were randomly assigned to receive fibrinolysis with usual care or coupled with mechanical cointervention, or primary PCI. To assess the impact of this strategy on time to treatment, the following randomly assigned patient groups were compared: prehospital versus in-hospital; those arriving at the hospital by ambulance versus ambulatory self transport; and those whose initial hospital care was a community versus PCI centre.
Of the 328 patients enrolled in the study, 221 received fibrinolysis and 107 received primary PCI. Compared with the in-hospital group, patients who underwent prehospital random assignment (44%, n=145) experienced a 48 min reduction in median (interquartile range) time from symptom onset to first study medication (87 min [65 min to 147 min] versus 135 min [95 min to 186 min]; P<0.001) and a 56 min reduction in time to first balloon inflation (148 min [117 min to 214 min] versus 204 min [166 min to 290 min]; P<0.001). Arrival by ambulance without prehospital random assignment (n=90) incurred a substantial delay from first medical contact to reperfusion (fibrinolysis 76 min [63 min to 105 min] and PCI 160 min [141 min to 212 min]) compared with prehospital random assignment (n=145; fibrinolysis 43 min [33 min to 54 min] and PCI 105 min [90 min to 127 min]) or ambulatory patients (n=93; fibrinolysis 47 min [32 min to 68 min] and PCI 108 min [85 min to 150 min]). Community (n=165) versus PCI hospital (n=163) random assignment was associated with a longer delay from first medical contact to reperfusion: fibrinolysis, 56 min versus 47 min (P=0.008) and primary PCI, 139 min versus 105 min (P=0.001).
Prehospital diagnosis, random assignment and treatment substantially reduced treatment delay with both pharmacological and mechanical reperfusion. Those activating the prehospital medical response system without receiving prehospital random assignment experienced the longest delay from first medical contact to reperfusion, indicating a lost opportunity to enhance ST elevation myocardial infarction patient outcomes.
近期研究及当代ST段抬高型心肌梗死指南强调了及时再灌注的重要性，并重新定义了传统的治疗时间指标，将院前急救人员作为首次医疗接触点纳入其中。然而，在系统研究救护车送医及从社区医院转至三级中心进行经皮冠状动脉介入治疗（PCI）过程中存在的固有延误方面，仍存在重要的知识空白。
早期ST段抬高型心肌梗死治疗选择（WEST）研究在首次医疗接触点启动治疗，包括院前接触。患者被随机分配接受常规治疗联合纤溶治疗或联合机械干预，或直接PCI治疗。为评估该策略对治疗时间的影响，对以下随机分组的患者组进行了比较：院前与院内；救护车送医与自行步行就医；初始就诊于社区医院与PCI中心。
该研究共纳入328例患者，其中221例接受纤溶治疗，107例接受直接PCI治疗。与院内组相比，院前随机分组的患者（44%，n = 145）从症状发作到首次研究用药的中位（四分位间距）时间缩短了48分钟（87分钟[65分钟至147分钟]对比135分钟[95分钟至186分钟]；P < 0.001），首次球囊扩张时间缩短了56分钟（148分钟[117分钟至214分钟]对比204分钟[166分钟至290分钟]；P < 0.001）。未进行院前随机分组而由救护车送医的患者（n = 90）从首次医疗接触到再灌注出现了显著延迟（纤溶治疗76分钟[63分钟至105分钟]，PCI治疗160分钟[141分钟至212分钟]），与院前随机分组的患者（n = 145；纤溶治疗43分钟[33分钟至54分钟]，PCI治疗105分钟[90分钟至127分钟]）或自行就医的患者（n = 93；纤溶治疗47分钟[32分钟至68分钟]，PCI治疗108分钟[85分钟至150分钟]）相比。社区医院（n = 165）与PCI医院（n = 163）随机分组的患者从首次医疗接触到再灌注的延迟更长：纤溶治疗分别为56分钟和47分钟（P = 0.008），直接PCI治疗分别为139分钟和105分钟（P = 0.001）。
院前诊断、随机分组和治疗显著减少了药物及机械再灌注治疗的延迟。那些启动院前医疗反应系统但未接受院前随机分组的患者从首次医疗接触到再灌注的延迟最长，这表明错失了改善ST段抬高型心肌梗死患者治疗结局的机会。
