Current status of emergency medical service use in ST-segment elevation myocardial infarction in China: Findings from China Acute Myocardial Infarction (CAMI) Registry

BACKGROUND

The mortality rate of myocardial infarction in China has increased dramatically in the past three decades. Although emergency medical service (EMS) played a pivotal role for the management of patients with ST-segment elevation myocardial infarction (STEMI), the corresponding data in China are limited.

METHODS

An observational analysis was performed in 26,305 STEMI patients, who were documented in China acute myocardial infarction (CAMI) Registry and treated in 162 hospitals from January 1st, 2013 to January 31th, 2016. We compared the differences such as demographic factors, social factors, medical history, risk factors, socioeconomic distribution and treatment strategies between EMS transport group and self-transport group.

RESULTS

Only 4336 patients (16.5%) were transported by EMS. Patients with symptom onset outside, out-of-hospital cardiac arrest and presented to province-level hospital were more likely to use EMS. Besides those factors, low systolic blood pressure, severe dyspnea or syncope, and high Killip class were also positively related to EMS activation. Notably, compared to self-transport, use of EMS was associated with a shorter prehospital delay (median, 180 vs. 245 min, P < 0.0001) but similar door-to-needle time (median, 45 min vs. 52 min, P = 0.1400) and door-to-balloon time (median, 105 min vs. 103 min, P = 0.1834).

CONCLUSIONS

EMS care for STEMI is greatly underused in China. EMS transport is associated with shorter onset-to-door time and higher rate of reperfusion, but not substantial reduction in treatment delays or mortality rate. Targeted efforts are needed to promote EMS use when chest pain occurs and to set up a unique regionalized STEMI network focusing on integration of prehospital care procedures in China.

TRIAL REGISTRATION

ClinicalTrials.gov (NCT01874691), retrospectively registered June 11, 2013.

Efficacy and safety of out-of-hospital intravenous metoprolol administration in anterior ST-segment elevation acute myocardial infarction: insights from the METOCARD-CNIC trial

STUDY OBJECTIVE

We seek to examine the efficacy and safety of prereperfusion emergency medical services (EMS)-administered intravenous metoprolol in anterior ST-segment elevation myocardial infarction patients undergoing eventual primary angioplasty.

METHODS

This is a prespecified subgroup analysis of the Effect of Metoprolol in Cardioprotection During an Acute Myocardial Infarction trial population, who all eventually received oral metoprolol within 12 to 24 hours. We studied patients receiving intravenous metoprolol by EMS and compared them with others treated by EMS but not receiving intravenous metoprolol. Outcomes included infarct size and left ventricular ejection fraction on cardiac magnetic resonance imaging at 1 week, and safety by measuring the incidence of the predefined combined endpoint (composite of death, malignant ventricular arrhythmias, advanced atrioventricular block, cardiogenic shock, or reinfarction) within the first 24 hours.

RESULTS

From the total population of the trial (N=270), 147 patients (54%) were recruited during out-of-hospital assistance and transferred to the primary angioplasty center (74 intravenous metoprolol and 73 controls). Infarct size was smaller in patients receiving intravenous metoprolol compared with controls (23.4 [SD 15.0] versus 34.0 [SD 23.7] g; adjusted difference -11.4; 95% confidence interval [CI] -18.6 to -4.3). Left ventricular ejection fraction was higher in the intravenous metoprolol group (48.1% [SD 8.4%] versus 43.1% [SD 10.2%]; adjusted difference 5.0; 95% CI 1.6 to 8.4). Metoprolol administration did not increase the incidence of the prespecified safety combined endpoint: 6.8% versus 17.8% in controls (risk difference -11.1; 95% CI -21.5 to -0.6).

CONCLUSION

Out-of-hospital administration of intravenous metoprolol by EMS within 4.5 hours of symptom onset in our subjects reduced infarct size and improved left ventricular ejection fraction with no excess of adverse events during the first 24 hours.