Clinical characteristics and in-hospital management strategies in patients with acute coronary syndrome: results from 2,096 accredited Chest Pain Centers in China from 2016 to 2021 : Cardiology Plus

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Clinical characteristics and in-hospital management strategies in patients with acute coronary syndrome: results from 2,096 accredited Chest Pain Centers in China from 2016 to 2021

Li, Linjie1; Zhou, Xin1; Jin, Zhengyang1; A, Geru1; Sun, Pengfei1; Wang, Zhuoqun1; Li, Yongle1; Xu, Chengyi2; Su, Xi3,*; Yang, Qing1,*; Huo, Yong4,*

Author Information
Cardiology Plus 7(4):p 192-199, October-December 2022. | DOI: 10.1097/CP9.0000000000000032
  • Open

Abstract

INTRODUCTION

Acute coronary syndrome (ACS) is one of the most common cardiovascular diseases (CVD) admitted to emergency department[1]. Previous studies showed a big gap in the level of ACS treatment in China vs developed countries, most notably, the delay of the treatment time of patients after disease onset and the long delay in the medical system after admission[2,3]. Chest Pain Centers are specialized facilities that provide integrated care for patients with acute chest pain, especially acute myocardial infarction (AMI). Previous studies in countries outside China have shown that the establishment of Chest Pain Centers significantly reduced the time to diagnosis of chest pain, shortened the time to ischemia–reperfusion treatment and hospitalization for ST segment elevation myocardial infarction (STEMI), reduced rehospitalization, and improved the quality of life of patients[4,5]. In China, Chest Pain Center accreditation is an important nationwide approach to improve the diagnosis, treatment, and clinical management of patients with acute chest pain, which has been shown to improve in-hospital outcomes of patients with AMI[6,7]. So far, limited information existed concerning the characteristics and in-hospital management strategies of ACS patients admitted to accredited Chest Pain Centers in China. In the present study, we therefore screened the Chest Pain Center database between January 1, 2016 to December 31, 2021 to describe and summarize patient characteristics, time delays, treatment strategies and in-hospital outcomes in all accredited Chest Pain Centers during this period, which would provide contemporary information regarding the temporal trends for ACS patient management in China.

METHOD

Data source and study population

The National Chest Pain Centers Program is the largest nationwide, multifaceted, continuous quality improvement initiative in China, which aims to monitor and improve the quality of care for patients with acute chest pain. In October 2019, the National Health Commission authorized the establishment of the China Alliance of Chest Pain Centers to standardize chest pain center accreditation further and promote implementation of chest pain centers in China. The program has set up a web-based unified register data system named Chinese Cardiovascular Association (CCA) Database-Chest Pain Center. Each hospital is responsible for its own data collection and reporting to the CCA Database-Chest Pain Center. Cases should be reported based on the data elements abstracted from medical charts. The data elements in the CCA Database-Chest Pain Center include patient characteristics, pre-hospital treatment and presenting features, in-hospital medication and reperfusion therapy, and in-hospital outcomes and discharge[8]. As of December 2021, there were 5,107 hospitals that registered the China Chest Pain Center accreditation project, of which 2,096 hospitals were accredited (1,047 in the standard version and 1,049 in the basic version).

We screened the Chest Pain Centers database for all case records for patients admitted to accredited Chest Pain Centers from January 1, 2016, to December 31, 2021. Patients diagnosed with STEMI, non-ST segment elevation myocardial infarction (NSTEMI), or unstable angina (UA) at admission were included in the analysis. The diagnoses were made by cardiologists according to standard clinical practicing guidelines on the basis of symptoms, electrocardiographic evidence, and cardiac troponin levels. We excluded the patients who were younger than 18 years old or had incomplete identity document information. The inclusion and exclusion criteria are shown in Figure 1.

F1
Figure 1.:
Study flow diagram.

The data were processed to remove all information that could reveal patients identity. Anonymized data are available through a formal application process and after review by the Data Management Committee of the CCA Database-Chest Pain Center. The study protocol was conducted in accordance with the Declaration of Helsinki (as revised in 2013) and approved by the institutional review board at the Tianjin Medical University General Hospital (IRB2022-WZ-145). Informed consent was waived due to the retrospective nature of the study.

Study variables

The study variables included diagnosis on admission (STEMI, NSTEMI, and UA), demographics (age, sex), pattern of patient arrival (emergency medical services, transfer, walk-in, and in-hospital onset), presenting symptoms, Killip class, risk factors (obesity, smoking, hypertension, hyperlipidemia, and family history of early-onset coronary artery disease), comorbidities (coronary artery disease, revascularization, atrial fibrillation, chronic heart failure, valvular heart disease, cerebrovascular disease, peripheral vascular disease, aortic aneurysm, chronic obstructive pulmonary disease, chronic kidney disease, chronic anemia, peptic ulcer, thyroid dysfunction and malignancy), time from first medical contact to first electrocardiogram (FMC-to-first ECG), time from symptom onset to first medical contact (S-to-FMC), time from pre-hospital electrocardiogram to door (pre-hospital ECG-to-D), time from symptom onset to call (S-to-Call), time from call to ambulance arrival, time from ambulance arrival to door (ambulance arrival-to-D), time from first medical contact to dual antiplatelet therapy (FMC-to-DAPT), time from door to wire crossing (D-to-W), time from first medical contact to needle (the beginning of thrombolysis) (FMC-to-Needle), time from first medical contact to reperfusion [including thrombolysis and percutaneous coronary intervention (PCI) therapy (FMC-to-Reperfusion), time from symptom onset to reperfusion (S-to-Reperfusion)], clinical outcomes (new-onset heart failure in hospital, cardiogenic shock, malignant arrhythmia, mechanical complications, infection, recurrent myocardial infarction, thromboembolism, ischemic stroke/transient ischemic attack, bleeding, respiratory failure, renal failure, and in-hospital mortality), transthoracic echocardiography (regional wall motion abnormality, ventricular aneurysm, and left ventricular ejection fraction), troponin I/T (PCI, pre-hospital thrombolysis, and in-hospital thrombolysis), and hospitals levels (categorized into grade IIIA/B/C, grade IIA/B/C, and grade I).

The following five elements about Chest Pain Center also collected: the basic framework, diagnosis and treatment of acute chest pain, cooperation between emergency medical services and the in-hospital emergency system, education and training, and continuous improvement. Chest Pain Centers were categorized into two types (standard version and basic version) by the committee on Accreditation of Chest Pain Centers. The area and the population in 2021 of each province were obtained from http://www.stats.gov.cn/. Missing information is provided in Supplementary Table 1, https://links.lww.com/CARDIOPLUS/A7 and Supplementary Figure 1, https://links.lww.com/CARDIOPLUS/A7.

Statistical analysis

Continuous variables with normal distribution are presented as the means and standard deviations. Continuous variables not following normal distribution are presented as the medians with 25th to 75th percentiles. Categorical variables are presented as absolute frequencies and percentages. Demographic and baseline characteristics were compared among the three groups of patients with STEMI, NSTEMI, or UA.

The diagnostic agreement rate was calculated based the discharge and admission diagnoses. To examine regional differences, we calculated the number of population per Chest Pain Center per 1,000 km2 for each province at the end of 2021. We used alluvial diagram to demonstrate different treatment strategies and in-hospital outcome of STEMI patients. We used Stata (version 15.1, StataCorp, College Station, TX, USA) for analysis.

RESULT

Baseline characteristics

The final analysis included a total of 1,745,118 patients. Admission diagnosis was STEMI in 699,476 patients (40.1%), NSTEMI in 349,572 (20.0%), and UA in 696,070 (39.9%) (Table 1). The mean age was 63.6 years, and 554,134 (31.8%) were women. The proportion of women was lower in patients with STEMI than with NSTEMI and UA. The walk-in percentage was 73.6% for the entire cohort, 57.3% in STEMI patients, 72.9% in NSTEMI patients, and 90.2% in UA patients. In contrast, the proportion of call-outs and transfers was significantly higher in STEMI patients than in NSTEMI and UA patients. STEMI patients were more likely to present with persistent chest tightness/chest pain, followed by NSTEMI patients, whereas UA often presented with intermittent chest pain/chest tightness. Killip class I was 77.1% for the entire cohort. Killip class IV was significantly higher in STEMI patients than in NSTEMI and UA patients (5.60%, 4.31%, and 1.18%, respectively). The rate of obesity, hyperlipidemia, and family history of early-onset coronary artery disease was similar among the three groups. The rate of smoking was higher in STEMI and NSTEMI than in UA. The proportion of hypertension was higher in NSTEMI and UA patients than in STEMI patients (56.9%, 59.2%, and 48.3%, respectively). Coronary artery disease, history of revascularization, and cerebrovascular disease were the most common coexisting conditions. Notably, NSTEMI patients were more likely to have atrial fibrillation, chronic heart failure, peripheral artery disease, chronic kidney disease, and anemia.

Table 1 - Demographic and clinical characteristics of the ACS patients on admission
Total (n = 1,745,118) Admission diagnosis
STEMI (n = 699,476) NSTEMI (n = 349,572) UA (n = 696,070)
Age, y
 Mean ± SD 63.6 ± 12.5 62.7 ± 13.0 64.8 ± 12.8 63.9 ± 11.7
 ≥18 to <55 424,365 (24.3) 195,252 (27.9) 77,328 (22.1) 151,785 (21.8)
 ≥55 to <70 735,861 (42.2) 281,274 (40.2) 139,299 (39.8) 315,288 (45.3)
 ≥70 584,892 (33.5) 222,950 (31.9) 132,945 (38.0) 228,997 (32.9)
Female, n (%) 554,134 (31.8) 168,338 (24.1) 106,742 (30.5) 279,054 (40.1)
Pattern of patient arrival, n (%)
 EMS 140,846 (8.07) 80,491 (11.5) 23,929 (6.85) 36,426 (5.23)
 Transfer 283,837 (16.3) 202,052 (28.9) 57,684 (16.5) 24,101 (3.46)
 Walk-in 1,283,864 (73.6) 400,733 (57.3) 254,982 (72.9) 628,149 (90.2)
 In-hospital onset 36,484 (2.1) 16,145 (2.3) 12,957 (3.7) 7,382 (1.1)
Clinical symptom, n (%)
 Persistent 782,840 (47.3) 496,612 (75.0) 146,569 (45.2) 139,659 (20.9)
 Intermittent 753,699 (45.6) 135,784 (20.5) 150,043 (46.3) 467,872 (70.1)
 Have dissipated 117,666 (7.1) 30,176 (4.6) 27,579 (8.5) 59,911 (9.0)
Killip class, n (%)
 I 1,257,371 (77.7) 511,060 (77.0) 251,790 (74.2) 494,521 (80.4)
 II 229,413 (14.2) 90,294 (13.6) 52,651 (15.5) 86,468 (14.1)
 III 72,646 (4.5) 25,431 (3.8) 20,115 (5.9) 27,100 (4.4)
 IV 59,108 (3.7) 37,216 (5.6) 14,606 (4.3) 7,286 (1.2)
Risk factors, n (%) n = 1,022,984 n = 399,309 n = 213,612 n = 410,063
 Smoking 291,273 (31.2) 144,424 (37.6) 65,839 (32.7) 81,010 (23.3)
 Obesity 54,423 (5.8) 23,240 (6.1) 11,900 (5.9) 19,283 (5.6)
 Family history of early-onset CAD 23,510 (2.5) 10,701 (2.8) 5,054 (2.5) 7,755 (2.2)
 Hypertension 505,524 (54.2) 185,502 (48.3) 114,444 (56.9) 205,578 (59.2)
 Hyperlipidemia 192,868 (20.7) 76,966 (20.0) 43,543 (21.7) 72,359 (20.9)
 Diabetes 208,232 (23.5) 81,522 (22.3) 50,444 (26.1) 76,266 (23.4)
Comorbidities, n (%) n = 1,022,984 n = 399,309 n = 213,612 n = 410,063
 CAD 441,045 (46.5) 154,686 (40.1) 94,539 (46.6) 191,820 (53.2)
 Revascularization 123,076 (25.2) 48,857 (27.2) 26,154 (25.0) 48,065 (23.5)
 Atrial fibrillation 40,568 (4.3) 14,952 (3.9) 10,801 (5.4) 14,815 (4.2)
 Heart failure 66,477 (7.9) 23,173 (6.8) 17,859 (9.8) 25,445 (7.9)
 Valvular heart disease 15,957 (1.7) 5,146 (1.3) 4,952 (2.5) 5,859 (1.7)
 Cerebrovascular disease 79,160 (9.0) 28,062 (7.7) 18,649 (9.7) 32,449 (10.0)
 Peripheral vascular disease 40,930 (4.6) 14,948 (4.1) 10,839 (5.6) 15,143 (4.7)
 Aortic aneurysm 1,322 (0.2) 401 (0.1) 433 (0.2) 488 (0.2)
 COPD 21,066 (2.4) 7,474 (2.0) 5,783 (3.0) 7,809 (2.4)
 Chronic kidney disease 33,254 (3.8) 12,249 (3.4) 11,678 (6.1) 9,327 (2.9)
 Anemia 26,270 (3.0) 9,586 (2.6) 9,187 (4.8) 7,497 (2.3)
 Peptic ulcer 17,291 (2.0) 7,147 (2.0) 4,043 (2.1) 6,101 (1.9)
 Abnormal thyroid function 19,229 (2.2) 6,091 (1.7) 4,801 (2.5) 8,337 (2.6)
 Malignancy 9,649 (1.1) 3,880 (1.1) 2,454 (1.3) 3,315 (1.0)
Data are expressed as n (%) or mean ± SD as appropriate.
ACS: acute coronary syndrome; CAD: coronary artery disease; COPD: chronic obstructive pulmonary disease; EMS: emergency medical services; NSTEMI: non-ST elevation myocardial infarction; STEMI: ST elevation myocardial infarction; UA: unstable angina.

Pre-hospital and in-hospital treatment and outcomes

The median FMC-to-First ECG of ACS patients was 3.8 (2.2 to 6.3) min, and the majority of patients (89.4%) had FMC-to-First ECG less than 10 min (Table 2). The median S-to-FMC was 260 (88.3 to 1444) min, and only 297,498 (17.1%) patients had S-to-FMC less than 60 min, The S-to-FMC was shorter in STEMI patients (157 min) than in NSTEMI and UA patients (391 and 509 min, respectively). A pre-hospital ECG was available in 19.7% of the patients in the entire cohort, and in 32.7 % of STEMI patients. The pre-hospital ECG-to-D was less than 15 minutes in 9.17% in the overall analysis, and significantly higher in UA patients (19.0%), than the other two groups (7.6% and 7.4%, respectively). In the patients admitted via emergency medical services, the median S-to-Call was 63.0 (20.0 to 220) min in the overall analysis, and significantly longer in NSTEMI patients (180 min) than in STEMI and UA patients (60.0 min for both). The median Call-to-ambulance arrival time and the median ambulance arrival-to-D were 18.3 (11.4 to 30.2) and 21.8 (10.9 to 35.0) min, respectively, and did not differ among the 3 groups.

Table 2 - Time delay and in-hospital outcomes
Total (n = 1,745,118) Admission diagnosis
STEMI (n = 699,476) NSTEMI (n = 349,572) UA (n = 696,070)
Pre-hospital
 FMC-to-First ECG ≤ 10 min, n (%) 1,404,974 (89.4) 548,883 (87.1) 273,535 (87.8) 582,556 (92.4)
 S-to-FMC ≤ 60 min, n (%) 297,498 (17.1) 155,339 (22.3) 48,332 (13.9) 93,827 (13.5)
 FMC-to-First ECG, min 3.8 (2.2–6.3) 3.6 (2.0–6.2) 3.9 (2.3–6.6) 3.9 (2.4–6.1)
 S-to-FMC, min 260.5 (88.3 to 1444.6) 157.4 (64.9 to 512.8) 391.9 (117.0 to 1531.0) 509.2 (117.2 to 3713.0)
 Pre-hospital ECG, n (%) 306,436 (19.7) 204,354 (32.7) 58,434 (19.1) 43,648 (7.0)
 Pre-hospital ECG-to-D ≤ 15 min, n (%) 28,068 (9.2) 15,506 (7.6) 4,287 (7.4) 8,275 (19.0)
EMS n = 140,846 n = 80,491 n = 23,929 n = 36,426
 S-to-Call, min 63.0 (20.0–220) 60.0 (20.0–180.0) 108.0 (30.0–495.0) 60.0 (20.0–210.0)
 Call-to-ambulance arrival, min 18.3 (11.4–30.2) 18.1 (11.1–30.0) 19.6 (12.1–33.0) 18.0 (11.4–29.3)
 Ambulance arrival-to-D, min 21.8 (10.9–35.0) 21.8 (10.9–35.0) 21.8 (10.9–35.0) 19.7 (13.1–30.6)
In-hospital
 FMC-to-DAPT ≤ 10 min, n (%) 177,008 (21.2) 116,355 (31.4) 20,149 (11.2) 40,504 (14.2)
PCI therapy n = 428,415 n = 37,4575 n = 42,496 n = 10,496
 D-to-W ≤ 60 min, n (%) 131,095 (30.6) 125,108 (33.4) 4,972 (11.7) 1,015 (9.7)
 D-to-W, min 75.3 (55.1–100.7) 72.1 (53.1–91.9) 112.2 (80.7–163.5) 124.7 (85.5–208.0)
Thrombolysis therapy
 FMC-to-Needle ≤ 30 min, n (%) NA 28,554 (45.9) NA NA
 FMC-to-Needle, min NA 32.3 (23.8–58.6) NA NA
Reperfusion therapy
 FMC-to-Reperfusion ≤ 90 min, n (%) 242,954 (50.2) 232,029 (54.1) 8,540 (19.3) 2,385 (21.4)
 S-to-Reperfusion ≤ 120 min, n (%) 66,340 (13.7) 63,749 (14.8) 1,815 (4.1) 776 (7.0)
 FMC-to-Reperfusion, min 89.8 (64.1–146.3) 85.9 (61.6–134.9) 145.9 (99.3–253.5) 143.1 (96.0–249.2)
 S-to-Reperfusion, min 258.0 (158.0–484.0) 243.0 (152.0–438.0) 488.0 (258.0–1030.0) 355.0 (206.0–848.0)
Clinical outcomes, n (%) n = 914,865 n = 379,334 n = 198,356 n = 337,175
 Cardiogenic shock 26,141 (2.9) 19,292 (5.1) 5,384 (2.7) 1,465 (0.4)
 Mechanical complication 1,864 (0.2) 1,486 (0.4) 289 (0.2) 89 (< 0.1)
 Infection 25,829 (2.8) 13,359 (3.5) 7,946 (4.0) 4,524 (1.3)
 Recurrent myocardial infarction 2,346 (0.3) 1,326 (0.4) 623 (0.3) 397 (0.1)
 Thromboembolism 1,731 (0.2) 1,144 (0.3) 334 (0.2) 253 (0.1)
 Ischemic stroke/TIA 3,316 (0.4) 1,570 (0.4) 891 (0.5) 855 (0.3)
 Bleeding 6,859 (0.8) 3,839 (1.0) 1,856 (1.0) 1,164 (0.4)
 Malignant arrhythmia 13,357 (1.5) 9,800 (2.6) 2,550 (1.3) 1,007 (0.3)
 Respiratory failure 10,518 (1.2) 6,484 (1.7) 3,208 (1.6) 826 (0.2)
 Renal failure 5,888 (0.6) 3,036 (0.8) 2,018 (1.0) 834 (0.3)
New-onset heart failure in hospital, n (%) 136,538 (8.8) 84,220 (13.1) 33,777 (10.6) 18.541 (3.2)
In-hospital mortality, n (%) 33,396 (2.0) 24,346 (3.6) 7,278 (2.1) 1,772 (0.3)
Transthoracic echocardiography, n (%) 652,408 (69.9) 271,708 (70.6) 142,075 (70.6) 238,625 (68.7)
 Regional wall motion abnormality, n (%) 203,499 (34.1) 124,417 (50.1) 46,247 (35.5) 33,104 (15.2)
 Ventricular aneurysm, n (%) 11,202 (1.9) 7,290 (3.0) 1,910 (1.5) 2,002 (0.9)
 LVEF, % 56.7 ± 10.6 54.2 ± 10.3 55.7 ± 11.2 60.2 ± 9.45
Troponin I/T, n (%) 1,487,193 (91.5) 597,560 (92.1) 317,780 (94.3) 571,853 (89.5)
Length of stay, d 7.0 (5.0–10.0) 8.0 (6.0–11.0) 7.0 (5.0–10.0) 6.0 (4.0–9.0)
Data are expressed as n (%) or mean ± SD as appropriate.
ACS: acute coronary syndrome; D-to-W: time from door to wire crossing; FMC-to-DAPT: time from first medical contact to dual antiplatelet therapy; EMS: emergency medical services; FMC-to-First ECG: time from first medical contact to first electrocardiogram; FMC-to-Needle: time from first medical contact to needle (the beginning of thrombolysis); FMC-to-Reperfusion: time from first medical contact to reperfusion (including thrombolysis and percutaneous coronary intervention therapy); NSTEMI: non-ST elevation myocardial infarction; Pre-hospital ECG-to-D: time from pre-hospital electrocardiogram to door; STEMI: ST elevation myocardial infarction; S-to-Call: time from symptom onset to call; S-to-Reperfusion: time from symptom onset to reperfusion; S-to-FMC: time from symptom onset to first medical contact; TIA: transient ischemic attacks; UA: unstable angina.

The FMC-to-DAPT was less than 10 min in 21.2% of the patients in the overall analysis, 31.4% in STEMI patients, 11.2% in NSTEMI and 14.2% in UA patients. In patients undergoing thrombolytic therapy for STEMI, the median FMC-to-Needle of STEMI patients was 32.3 (23.8 to 58.6) min, and only 28,554 (45.9%) patients had FMC-to-Needle less than 30 min. In patients undergoing PCI, the median FMC-to-W was 97.8 min in the overall analysis and 91.4 min in STEMI. The median D-to-W was 75.3 (55.1 to 101) min in the overall analysis and 72.1 (53.1 to 91.9) min in STEMI. The D-to-W was less than 60 min in 33.4% for STEMI patients, 11.7% for NSTEMI and 9.67% for UA patients. The median FMC-to-Reperfusion was 89.8 (64.1 to 146) min in the overall analysis and 85.9 (61.6 to 135) min for STEMI. The FMC-to-Reperfusion was less than 90 min in the overall analysis, 54.1% for STEMI, 19.3% for NSTEMI and 21.4% for UA. Patients with STEMI or NSTEMI were more likely to develop cardiogenic shock, mechanical complications, and infections than patients with UA. The rate of in-hospital new-onset heart failure was 8.81% in the overall analysis, 13.1% for STEMI, 10.6% for NSTEMI, and 3.16% for UA. In-hospital mortality was 2.0% in the overall analysis, 3.6% for STEMI, 2.1% for NSTEMI, and 0.3% for UA.

Transthoracic echocardiography was conducted in 652,408 (69.9%) patients. Half of STEMI patients had regional wall motion abnormality, higher than in NSTEMI and UA patients (35.5% and 15.2%, respectively). Left ventricular ejection fraction was slightly lower in STEMI patients than in NSTEMI and UA patients (54.2%, 55.7% and 60.2%, respectively). Troponin I/T testing results were available in 1,487,398 (91.5%) patients. The median length of hospital stay was 7 days in the overall analysis, 8 days for STEMI, 7 days for NSTEMI, and 6 days for UA.

The diagnostic agreement rate remained stable for STEMI and NSTEMI. But decrease slightly for UA (Figure 2). Among patients admitted with a diagnosis of UA, the proportion of those discharged with a diagnosis of NSTEMI has increased year by year (Supplementary Figure 2, https://links.lww.com/CARDIOPLUS/A7).

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Figure 2.:
Change in diagnostic agreement rates for ACS admissions from 2016 to 2021. The blue line represents STEMI patients, the yellow line represents NSTEMI patients, and the gray represents UA patients.

Reperfusion strategies for STEMI

Among the STEMI patients, 62.8% underwent primary PCI (Table 3). The rate of primary PIC was lower in grade I and II hospitals than in grade III hospitals (44.8% and 68.3%, respectively). There was a trend for increasing rate of primary PCI in grade II hospitals during the study period. The rate of pre-hospital thrombolysis was 8.97% in the overall analysis, 10.2% in grade III hospitals and 3.23% in grade I and II hospitals. There was a trend for increasing rate of pre-hospital thrombolysis. The rate of in-hospital thrombolysis was 8.17% in the overall analysis, 21.9% in grade I and II hospitals and 3.97% in grade III hospitals. There was a trend for decreasing rate of in-hospital thrombolysis in grade I and II hospitals.

Table 3 - Reperfusion strategy in STEMI patients in 2016–2021
Total 2016 2017 2018 2019 2020 2021
Primary PCI, n (%) 429,045 (62.8) 2,853 (63.5) 34,870 (62.5) 68,280 (62.5) 90,155 (62.0) 105,197 (62.0) 127,690 (64.4)
 Grade III 357,292 (68.3) 2,577 (67.0) 31,963 (66.7) 60,525 (67.6) 75,966 (68.3) 85,215 (68.4) 101,046 (69.3)
 Grade I and II 71,753 (44.8) 276 (34.2) 2,907 (36.3) 7,755 (39.4) 14,189 (41.5) 19,982 (44.3) 26,644 (50.7)
Pre-hospital thrombolysis, n (%) 27,642 (9.0) 181 (8.9) 1,691 (5.8) 3,526 (6.3) 5,279 (7.7) 7,614 (10.5) 9,351 (11.7)
 Grade III 25,919 (10.2) 86 (5.3) 1,430 (5.7) 3,319 (7.2) 4,963 (9.0) 7,212 (12.0) 8,909 (13.5)
 Grade I and II 1,723 (3.2) 95 (23.9) 261 (6.2) 207 (2.1) 316 (2.4) 402 (3.4) 442 (3.3)
Hospital thrombolysis, n (%) 55,839 (8.2) 332 (7.4) 3,642 (6.5) 7,374 (6.8) 11,208 (7.7) 15,936 (9.4) 17,353 (8.8)
 Grade III 20,759 (4.0) 121 (3.3) 1,371 (2.9) 2,412 (2.7) 3,209 (2.9) 6,006 (4.8) 7,640 (5.2)
 Grade I and II 35,080 (21.9) 211 (26.2) 2,269 (28.3) 4,961 (25.2) 7,996 (23.4) 9,930 (22.0) 9,713 (18.5)
Data are expressed as n (%) or mean ± SD as appropriate.
PCI: percutaneous coronary intervention; STEMI: ST elevation myocardial infarction.

Figure 3A shows the antiplatelet drug, reperfusion strategies and in-hospital outcome in STEMI patients admitted to Chest Pain Centers. Among the four reperfusion strategies, the lowest mortality rate was observed in patients received thrombolysis combined with PCI (1.48%), followed by patients treated with PCI only (2.26%). In addition, the mortality rates were 6.00% and 9.14% in patients with thrombolysis only and neither thrombolysis nor PCI, respectively. Figure 3B shows the in-hospital mortality rates for different reperfusion strategies. In-hospital mortality rate was higher in patients treated with thrombolysis only, as well as neither thrombolysis nor PCI, than those treated with PCI only and those received thrombolysis combined with PCI. There was a trend for increasing in-hospital mortality rate in patients treated with thrombolysis only and in patients treated with neither thrombolysis nor PCI. Detailed information is available in Supplementary Table 2, https://links.lww.com/CARDIOPLUS/A7.

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Figure 3.:
Temporal change in different reperfusion strategies and corresponding mortality in STEMI patients from 2016 to 2021. A, the alluvial diagram for difference reperfusion strategies and outcome for STEMI.From the left to the right, the three columns represent the antiplatelet drug therapy, reperfusion strategies and their outcome, respectively. B, The in-hospital mortality rates for different reperfusion strategies from 2016 to 2021.No thrombolysis and no PCI treatment includes other reperfusion measures such as coronary artery bypass grafting and no reperfusion measures.

Current status of nationwide Chest Pain Center accreditation

By the end of 2021, a total of 2,096 Chest Pain Centers have been accredited (1,047 in the standard version and 1,049 in the basic version). Chest Pain Center accreditation covered 31 administrative units of the Chinese mainland. There is at least one Chest Pain Center in 321 county-level municipality nationwide, achieving 96% coverage. Figure 4 depicts the number of population per Chest Pain Center covered for each 1,000 km2 at the province level in 2021. Supplementary Figure 3, https://links.lww.com/CARDIOPLUS/A7 depicts the number of accredited Chest Pain Centers at the province level by the end of 2021.

F4
Figure 4.:
Geographic variation of Chest Pain Centers accreditation. The map shows the number of population per Chest Pain Center per 1,000 square kilometers in each province in China by the end of 2021.

DISCUSSION

The China Chest Pain Center accreditation project has achieved significant improvement in the management of ACS patients[6,7]. Results from the current study supported the continuing improvement in ACS management, and revealed some important areas for further improvement.

For STEMI patients, emergent reperfusion therapy remains the immediate priority, as emphasized in the most recent European and American guidelines[9,10]. Although current guidelines recommend primary PCI as the first-choice reperfusion strategy for STEMI patients, physicians often face the decision to undergo PCI-related delay or immediate thrombolysis and must consider a variety of circumstantial issue, including weather, resources and location. In the current study, 62.8% of STEMI patients underwent primary PCI, representing a substantial increase over the 46.0% primary PCI in 2013 and 2014, as reported by the Chinese Acute Myocardial Infarction (CAMI) registry study[3]. Importantly, the proportion of primary PCI performed in grade I and II hospitals increased over the study period, with a concomitant decrease in the proportion of in-hospital thrombolysis Consistent with a previous study that reported a significant increase of thrombolysis during the COVID-19 outbreak[11], we noticed an increase in in-hospital thrombolysis in grade III hospitals in 2020 to 2021 compared to period, likely due to the impact of the COVID-19 epidemic.

The current study also revealed a reperfusion strategy-dependent difference in in-hospital prognosis among STEMI patients. Mortality was higher in patients treated with thrombolysis only and those neither received thrombolysis nor PCI than those treated with PCI and thrombolysis combined with PCI. In comparison to a “watch-and-wait” strategy, early routine angiography with subsequent PCI (if needed) after thrombolysis reduced the rate of reinfarction and recurrent ischemia[9]. In our study, only half of the patients with thrombolysis were subsequently treated with PCI therapy. Early angiography with subsequent PCI if indicated after successful thrombolysis needs to be promoted.

Previous studies have shown a 7.5% increase in 1-year mortality risk for every 30 min delay in STEMI patients[12]. In our study, median D-to-W for STEMI patients treated with PCI is 75 min. The CAMI registry showed that median D-to-B was 105 min in 12,695 STEMI patients in 2013 to 2014, and only 32.6% could meet the guideline recommendation of D-to-B ≤ 90 min3. Notably, in the United States, the median D-to-B for patients with un-transferred STEMI in 2014 was 59.1 min[13]. Therefore, although the Chest Pain Center accreditation has shortened the time delay for patients with myocardial infarction, there is still an urgent need for further improvement in China.

Our analysis found a gradual decline in the diagnostic agreement rate for UA from 2016 to 2021. Among patients with undiagnosed UA, the rate of diagnosis of NSTEMI gradually increased, probably due to the increasing adoption of high-sensitivity troponin. The implementation of increasingly analytically sensitive troponin assays has contributed to a higher incidence of NSTEMI and a lower incidence of UA[14]. In addition, due to the acceleration of in-hospital care for ACS patients, some NSTEMI patients are admitted earlier before their cardiac enzymes are not elevated.

Pre-hospital 12-lead ECG could provide critical information in triaging patients with suspected ACS[15]. A pre-hospital ECG was available in 19.7% in the overall analysis that included all three groups, and 32.7% of STEMI patients, lower than the 23% and 45% reported by the German Chest Pain Center[16], probably due to fewer patients admitted via ambulance in the current study. Previous studies have shown similar 30-day and 5-year follow-up mortality rates for pre-hospital thrombolysis with subsequent intervention compared with primary PCI, and lower 5-year mortality rates for pre-hospital thrombolysis in patients treated within 2 h of symptom onset[17]. Moreover, pre-hospital diagnosis and thrombolysis by trained paramedics in ambulances could reduce the time to thrombolysis in real-life STEMI patients by nearly an hour and reduce 1-year mortality by 30% compared with routine in-hospital thrombolysis[18]. The limited number of pre-hospital thrombolysis in China may be due to insufficient training of pre-hospital emergency care personnel and awareness of early diagnosis, risk stratification, and thrombolytic treatment options for patients with acute chest pain. Therefore, it is crucial to strengthen the training of emergency personnel.

The current study revealed a low percentage of S-to-FMC <60 min, a few patients admitted through EMS, and a long S-to-Call. These findings may have contributed to the relatively long pre-hospital time. The underlying causes may include a lack of awareness and specific profile of clinical manifestations of ACS in the Chinese population. The S-to-FMC represent a particularly poorly controlled link in the overall management. Efforts should be made to shorten the S-to-FMC. Public awareness of CVD and signs suggestive of ACS should also be further promoted by Chest Pain Centers in China.

In summary, the certification of the Chest Pain Centers has shortened the in-hospital treatment time for ACS patients, improved the proportion of primary PCI for STEMI patients, and reduced mortality. The in-hospital emergency process of the Chest Pain Centers has been fully optimized and improved. However, our analysis revealed the shortcomings of pre-hospital emergency treatment, such as less pre-hospital ECG transmission and relatively delayed pre-hospital treatment time, which suggests that the important issues to be solved now are mainly the connection from pre-hospital to in-hospital and in-hospital to out-of-hospital and the construction of a regional collaborative care network with united treatment and rapid and accurate transfer at all grades of hospitals.

The present study had several limitations. First, the current study included only data from accredited Chest Pain Centers and therefore may not represent the overall spectrum. As such, problems may have been under-estimated, and the magnitude of the under-estimation remains unknown. Second, the online case reporting platform for Chest Pain Center database is in the early stage and needs modification in a variety of aspects, particularly missing data on risk factors, comorbidities, and clinical outcomes.

CONCLUSION

The current study provided an overall description of the clinical characteristics of ACS patients in China. The results on management pattern and in-hospital outcomes of STEMI patients identified important areas for further improvement in ACS patient management in China.

FUNDING

This work was supported by National Science Foundation of China (82270349) and Tianjin Key Medical Discipline (Specialty) Construction Project (TJYXZDXK-069C).

AUTHOR CONTRIBUTIONS

LL, XZ, and CX participated the research design. All authors participated the performance of the research. All authors contributed new reagents or analytic tools. LL, XZ, and Z. J participated the data analysis. LL and XZ participated the writing of the paper.

CONFLICTS OF INTEREST STATEMENT

Yong Huo is an Editorial Board members of Cardiology Plus. The article was subject to the journal’s standard procedures, with peer review handled independently of the Editorial Board members and the research groups.

DATA SHARING STATEMENT

The data, analytic methods, and study materials are available for onsite audit by third parties for purposes of reproducing the results or replicating the procedure.

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Keywords:

Acute coronary syndromes; Chest Pain Center; Percutaneous coronary intervention; Myocardial reperfusion injury; ST elevation myocardial infarction

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