Our study found that ACS had significant delays in emergency procedure and an apparent drop in invasive therapy; the pandemic was associated with increased non-invasive therapy, especially for NSTE-ACS.
ACS often has acute chest pain as the onset symptom and further leads to heart failure, arrhythmia and even cardiac arrest . Early identification and intervention for ACS contributes to improve cardiovascular outcomes, thus chest pain emergency is established to cope with these conditions . Under a unified procedure, ACS patients are diagnosed, transferred and treated through chest pain emergency to reduce ischemic risk . In STEMI, PPCI is generally recommended as priority while sometimes thrombolysis could be also considered as supplement to ensure timely reperfusion . In NSTE-ACS, therapy strategy is mainly based on evaluation of ischemic risk; high-risk patients including hemodynamic instability, recurrent or refractory chest pain, malignant arrhythmia and severe heart failure should perform early invasive treatment within 24 hours or even 2 hours; medication could be considered to be optional for "relatively stable" patients . COVID-19 not only directly increased cardiovascular risk through biological mechanisms, but also affected the prognosis of ACS patients by disrupting conventional treatment procedure . Although previous studies provided some evidence of the pandemic's impact on ACS, this impact still remained unclear and unquantified in a non-epicenter.
Our findings firstly revealed decreased admissions and significant process delays after the first-wave epidemic. In hot-spot regions, similar results were also reported but larger reduction of hospitalization occurred in NSTE-ACS [24, 25]. However, changes in ACS composition were not observed in our study maybe ascribed to relatively low-intensity epidemic and active admission. We proposed the main explanations for the decline in hospitalization. Firstly, the patients preferred to social distancing and medical avoidance owing to fear of infection. Secondly, strict social restrictions were not conducive for patients to obtain timely medical assistance at symptom onset. Thirdly, conventional treatment-oriented mode was transformed into epidemic control-oriented mode in medical institutions that meant more resources were spent on epidemic management thus the capacity for treatment might be weakened. Of note, although ACS had universal prolongations in emergency timelines, the delays in NSTE-ACS seemed more serious than in STEMI after the outbreak. Consistently, Metzler et al. showed a significant increase of ischemic time for ACS in Austria, yet lack of time-series analysis for emergency procedures . Hamadeh et al. found the pandemic greatly affected STEMI presentation and care via process delay in a non-hot-spot region from America, but limited to small sample size and non-first-phase pandemic . Arai et al. discovered that NSTEMI had longer time for transfer and examination than STEMI in Japan, whereas no considering season characteristics . This effect should not be ignored considering that our data derived from a non-hot-spot region. Longer delay on NSTE-ACS might be mainly attributed to relatively lower ischemic risk and conservative response.
In terms of invasive therapy, Garcia et al. showed an estimated 38% reduction in cardiac catheterization laboratory activations during the early phase of pandemic in U.S . Kwok et al. revealed a decline in PPCI by 43% following the lockdown in England . Xiang et al. reported an approximately 60% drop in epicenter (Hubei province) from China after the outbreak . Likewise, our study found both PPCI for STEMI and early invasive treatment for NSTE-ACS dropped significantly. PPCI was still the preferred option for reperfusion in STEMI from our region rather than thrombolysis that also exhibited good adaptability of catheter-labs to the epidemic. Consistent with process delays, the proportion of invasive therapy in NSTE-ACS declined more than in STEMI suggesting conservative therapeutic behaviors. For STEMI, non-PPCI was more severely affected by the pandemic manifested as few thrombolysis and serious in-hospital delays that implied considerable non-PPCI patients rejected basic reperfusion therapy. This might be due to frequent informed risks and excessive protective measures in hospital, which further increased anxiety and insecurity of patients and reduced medical compliance. The absence of thrombolysis as supplement for PPCI would greatly increase the risk of life-threatening adverse events, thus it is essential for STEMI rescue to optimize in-hospital procedure . Moreover, our study further indicated whether STEMI or NSTE-ACS, the pandemic increased the probability of non-invasive therapy in a non-epicenter. This surge in non-invasive strategy derived from both patient-level and hospital-level. On the one hand, patient's decision on treatment become more negative subjected to individual psychology affected by the pandemic; on the other hand, decision-making from hospital tended to be cautious in treatment based on prevention of nosocomial infections and lack of medical resources. As a non-hot-spot region under the first-wave epidemic, our findings might provide references for emergency ACS practice to other current non-epicenters.
Our study had several limitations. First, this study was subject to the biases inherent to its retrospective design. Second, clinical characteristics and timeline parameters were assessed by trained physicians in each center without central reconfirmation, potentially resulting biases and errors. Third, our study had a relatively small sample size and no longitudinal analysis. Fourth, the absence of PPCI parameters limited further analysis for mechanical reperfusion procedure. Last, it remained unclear how local policies of each hospital had altered due to the first-wave pandemic that might affect emergency procedure for chest pain.