Abstract

Study Design and Setting

This retrospective, observational study was conducted at Hartford Hospital, an 890-bed tertiary care medical center in Hartford, Connecticut. The study was approved by the Hartford Hospital institutional review board, with waiver of the requirement to obtain informed consent.

Study Population and Definitions

Data from all consecutive patients with STEMI referred for primary PCI between January 1, 2019, and December 31, 2021, were analyzed. Patients were classified either as direct presenters, who presented directly or were transported from home to the emergency department (ED) by emergency medical services, or as transfer patients, who were initially diagnosed with STEMI at an outlying hospital and emergently transferred for PCI. Standard definitions of door-to-balloon (DTB) and first medical contact–to–device (FMC-D) times for STEMI direct presenters and FMC-D times for STEMI transfer patients were used. Late STEMI presentation was defined as hospitalization beginning more than 12 hours after symptom onset.

Statistical Analysis

Continuous variables are expressed as mean (SD) or median (IQR) and were compared using an analysis of variance or the Kruskal-Wallis test, respectively, followed by post hoc comparisons with Bonferroni corrections. Categorical variables were analyzed using the χ² test or Fisher exact test, as appropriate. All outcomes were considered significant at P < .05. The statistical analyses were performed with SPSS, version 21.0 (IBM Corporation).

STEMI Treatment Times

For direct presenters, median DTB time increased from 37 minutes (IQR, 25–54 minutes) in 2019 to 53 minutes (IQR, 36–73 minutes) in 2020 and then decreased to 48 minutes (IQR, 35–59 minutes) in 2021 (P < .001; P < .001 for 2019 vs 2020). Similarly, median FMC-D time increased from 70 minutes (IQR, 57.5–85 minutes) in 2019 to 82 minutes (IQR, 66–93 minutes) in 2020 and then decreased to 75 minutes (IQR, 64–86 minutes) in 2021 (P = .002; P = .001 for 2019 vs 2020). Although decreases in DTB and FMC-D times between 2020 and 2021 were not significant in post hoc comparisons, increases in 2020 treatment times followed by subsequent decreases in 2021 were directly related to median ED evaluation time (30 minutes in 2019, 41 minutes in 2020, 22 minutes in 2021; P < .001) and not to median time of coronary revascularization after transfer to the cardiac catheterization laboratory.

For transfer patients, the median FMC-D time increased from 110 minutes (IQR, 96–145 minutes) in 2019 to 133 minutes (IQR, 109.5–163 minutes) in 2020 and then decreased to 118 minutes (IQR, 102–143 minutes) in 2021 (P = .005; P = .004 for 2019 vs 2020). Treatment times are summarized in Table II and illustrated in Figures 1 and 2.

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TABLE II Median STEMI Treatment Times ^a

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STEMI In-Hospital Mortality

Observed in-hospital mortality increased from 3.6% in 2019 to 5.2% in 2020 and 6.4% in 2021 (P = .352). Death occurred secondary to COVID-19 illness in 1 patient in 2020; there were no COVID-19 deaths in 2019 and 2021 (P = .384). Patients in 2020 and 2021 had the highest rates of late presentation (P = .028; P =.036 for 2019 vs 2021) and late mechanical complications (P = .021). Four patients in 2020 died from late mechanical complications, with ventricular septal rupture in 1 patient, free-wall rupture in 2 patients, and ruptured papillary muscle in 1 patient; no mechanical complications were observed in 2019 and 2021. In addition, 2020 and 2021 rates of preprocedure cardiac arrest and the 2020 rate of presentation with cardiogenic shock increased compared to 2019 rates, although these differences were not statistically significant. Table III lists the mortality rates and underlying clinical risk factors for patients during the 3 time periods.

TABLE III In-Hospital Mortality Risk Factors and Outcomes

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Impact on STEMI Volumes

The first case of COVID-19 in Connecticut was diagnosed on March 6, 2020, and “Stay Safe, Stay Home” lockdown orders were issued on March 24, 2020.⁸ Subsequent dramatic increases in COVID-19 cases, hospitalizations, and deaths peaked in April 2020 and again in January 2021. An early decrease was reported in STEMI activations by 38% during March 2020.⁹ This early decrease was offset by increasing STEMI volume through 2020 and a persistent increase in 2021.

Several reports from healthcare systems have demonstrated different data regarding the rates of admission and PCI use for patients presenting with STEMI, especially early during the pandemic.^10–16 In a study by Wilson et al¹¹ from a single center in the United Kingdom, weekly PCI referrals decreased by 42.8% and STEMI presentations by 53% in the early phases of the pandemic. A study by Rinfret et al¹² that used a countrywide survey in Canada from all cardiac catheterization laboratories found a 16% reduction of STEMI PCI during the first wave of the pandemic compared with the control period. These reports have been updated by other studies showing an actual increase in STEMI volume following the initial wave of the pandemic. Indeed, a study by Trabattoni et al¹⁶ from Italy demonstrated that the total acute coronary syndrome volume increased in 2020 by 55% and STEMI volume by 46%.¹⁶ These findings are in contrast to initial data from the Italian experience showing a decrease in acute coronary syndrome presentations during the country's initial lock-down period.¹⁰

Impact on STEMI Treatment Times

Multiple studies have reported on the impact of the pandemic on quality metrics, including DTB and FMC-D times.^17–21 In a study by Fardman et al¹⁷ from Israel, the median time from hospital admission to reperfusion in patients with STEMI increased significantly by 7 minutes in the COVID-19 era. In another study by Kite et al¹⁸ that compared data from the International COVID-ACS Registry with 2018–2019 data from the British Cardiovascular Intervention Society, mean DTB time increased significantly by 46 minutes in the COVID-STEMI population. Last, in a study by Garcia et al,¹⁹ data from 18 STEMI centers in the United States were collected before and after the initiation of pandemic mitigation measures. The study demonstrated that DTB time increased on average by 20%. The present study results are in agreement with these previous reports, with initial increases in both DTB and FMC-D times in direct presenters and an increase in FMC-D time in transfer patients in 2020, followed by improvement in all treatment times in 2021.

An important factor underlying prolonged treatment times has been the necessary assessment of admitted patients by ED personnel to diagnose and treat possible COVID-19 illness, including nasopharyngeal testing for the virus and possible additional testing, including chest x-ray, echocardiogram, and chest computed tomography examination. By definition, this obligatory pre-PCI ED evaluation has eliminated the time saved through catheterization laboratory preactivation. Before the onset of the COVID-19 pandemic, routine STEMI care included obtaining a prehospitalization electrocardiogram by emergency medical services personnel, notification of an incoming STEMI case, and potential bypass of the ED. As documented in the present study, increases in DTB and FMC-D times in direct presenters in 2020 were related to an increase in the time of ED evaluation, with no significant change in the time of coronary revascularization following entry into the cardiac catheterization laboratory. Moreover, with ongoing standardization of viral testing and patient triage, decreases in ED evaluation time in 2021 were associated with improvements in all treatment times.

Another important factor that may have affected an institution's ability to respond to patients with STEMI in an appropriate format in 2020 and 2021 is the impact of COVID-19 illness or quarantine on hospital personnel, resulting in critical staff shortages; however, this factor was not relevant to the current study because ED and cardiac catheterization staffing at the hospital remained unchanged from 2019 to 2021.

Impact on Mortality

Although the increase in observed mortality in 2020 and 2021 compared with 2019 was not statistically significant, several important observations should be made. First, death secondary to COVID-19 illness was documented in only 1 patient in 2020, accounting for a small percentage of the 40 patients who died during the 3 time periods. Second, apart from the fact that longer DTB and FMC-D times have been associated with increasing STEMI mortality, late patient presentation after the onset of symptoms, preprocedure cardiac arrest, and presentation with cardiogenic shock have all been identified as independent predictors of in-hospital death. Finally, late mechanical complications were noted in the 2020 subgroup, with a P = .021 compared with 2019 and 2021.

The results of the current study support these observations and are in agreement with previous reports describing the impact of the COVID-19 pandemic on STEMI mortality.^{3,11,14,17,22–25} A study by Wilson et al¹¹ from the United Kingdom showed a trend toward higher in-hospital mortality, although this trend was not statistically significant (14.5% vs 11.0%; P = .47) in a comparison of before and during the COVID-19 pandemic. In a German registry report,¹⁵ there was a higher prevalence of cardiogenic shock and preprocedure cardiac arrest (21.9% vs 14.2 and 14.3% vs 11.1% respectively; P < .01) in a comparison of 2020 data and 2006–2019 data. Moreover, mortality increased from 8.4% to 12.8% (P < .01).¹⁵ Similarly, Fardman et al found not only a significant increase in both cardiogenic shock and in-hospital mortality during the pandemic but also a 4-fold increase in mechanical complications (free-wall rupture, ventricular septal defect, or moderate or severe mitral regurgitation).

Potential Factors Underlying STEMI Outcomes in 2021

Several possible explanations may account for the observed improvements in STEMI treatment times without significant improvement in mortality during 2021. As discussed above, obligatory treatment pathways were established early in the pandemic for the ED clinical assessment, nasopharyngeal polymerase chain reaction testing, and triage with possible isolation for all patients presenting to the hospital. Although an immediate effect of this policy was to invalidate the potential time benefit of catheterization laboratory preactivation with bypass of the ED, the efficiency of this process has improved with a decreasing amount of time spent in the ED. A proposal to potentially further improve this process is to perform initial patient assessment with viral testing in the catheterization laboratory, allowing for the return of prepandemic catheterization laboratory preactivation with complete bypass of the ED and transport of the patient directly to the catheterization suite.

Despite improving treatment times in 2021, observed in-hospital mortality has not significantly decreased. One possible explanation for this finding is the persistence of increased late presentation in 2021 patients. An increase in late presentation and preprocedure complications as a result of patient reluctance to seek emergency medical care has been documented during the pandemic.^26–28 Despite decreasing numbers of COVID-19 infections, the availability of improved COVID-19 treatment modalities, increasing patient vaccinations, and efforts to increase public awareness of the consequences of delaying urgent care, the results of this study suggest that patient delays in seeking urgent evaluation and treatment are still widespread.

Study Limitations

This study has multiple important limitations. First, this is a single-center, retrospective study, and the data might not be generalizable especially with the previously mixed results from other published reports. Second, the small volume of studied patients and their adverse outcomes did not provide sufficient power to detect statistically significant differences with respect to preprocedure events, including cardiac arrest and cardiogenic shock, and subsequent mortality. Future studies with increased patient volume allowing for appropriate statistical power are required to confirm these results. Third, patient mortality was not risk stratified. Finally, a full understanding of the impact of COVID-19 on patients with acute coronary syndromes must include data on patients with unstable angina and non-STEMI, as well as the STEMI population.