Effects of performing electrocardio‐graphy in the community on overall coronary artery ischemia time in patients with acute myocardial infarction

Primary percutaneous coronary intervention (PCI) is the optimal choice of reperfusion for patients with acute ST-segment elevation myocardial infarction (STEMI). Randomized multicenter studies have shown that compared to thrombolysis, using PCI for thrombolysis and reperfusion could effectively improve short-term mortality rates and the incidence of repeated non-fatal myocardial infarction (MI). Door to balloon (DTB) time has been acknowledged as an index for PCI evaluation. Shortening DTB time could reduce mortality rates, increase long-term survival rates, and preserve left ventricular function. Current guidelines suggest that DTB time should be shorter than 90 min. In a multicentre study performed in Beijing, China, the median DTB time was 135 min, suggesting that PCI needs to be improved in Chinese patients with STEMI. The diagnostic procedure, traffic condition, patient wishes and hospital capability may influence DTB time in China. By pre-hospital 12-lead electrocardiography (ECG),DTB time can be greatly saved. The medical model in China is unfavourable for diagnosis and treatment of cardiac diseases in community clinics. Patients with STEMI need to be transferred to major hospitals for diagnosis, which could delay cardiac disease treatment. Here we established a local cooperative model of chest pain diagnosis and treatment involving major hospitals that could perform PCI and clinicians from community clinics, and emergency physicians. Remote ECG examination equipment is accessible in communities, which makes it possible to convey and review ECG data online. When patients with chest pain seek medical care in community clinics, ECG data could be conveyed to major hospitals for diagnosis; meanwhile, the patients are also transferred to the hospital for PCI treatment. We believed that performing ECG for patients with chest pain in the community could facilitate the early diagnosis of myocardial infarction and shorten the time of ischemia. To test this hypothesis, we carried out comparisons between phase 1 and phase 2 data of patients. The phase 1 of the present study was performed between January 2010 and December 2011. During this phase, no 12-lead ECG examinations were performed in the community for patients with chest pain; rather, the patients were transferred to the hospital emergency room (ER) for the ECG examinations. After informed consent was obtained from the patients with STEMI, emergency PCI treatment was performed. Phase 2 of the present study was performed between January 2012 and December 2013. In this phase, 12-lead ECG examinations were performed for patients with chest pain who came to community clinics for medical care to help with the early diagnosis of STEMI. The patients were then transferred to the hospital ER, they provided informed consent, and emergency PCI was performed. In this non-randomized self-controlled clinical trial, patients with STEMI who received PCI treatment at the Affiliated Hospital of Hangzhou Normal University were included. The ECG examinations were performed by trained experienced clinicians. In the first phase, 54 patients were transferred from community clinics to hospital ER and ECG examinations were performed by trained emergency physician and biomarkers of myocardial necrosis were examined to diagnose STEMI. Fifteen patients were deemed ineligible; therefore, 39 patients with STEMI were enrolled in the first phase study. In the second phase, 1140 patients underwent a 12-lead ECG examination in the community by trained general practitioners, among whom 71 (6.23%) were diagnosed with suspicious STEMI and transferred to the hospital ER. Patients with suspicious STEMI were defined as chest pain manifestation and with show ST segment and T wave change in ECG. Forty-four of these patients were ultimately diagnosed with STEMI according to diagnostic criteria. Among them, 13 were deemed ineligible; therefore, 31 patients with STEMI were included in the second phase study. Table 1 shows the patients’ baseline characteristics in each study phase. No significant difference was found between the two phases. Table 2 shows that the onset to community clinic time was not significantly different between the second and first phases