Impact of COVID‐19 pandemic on the management of nonculprit lesions in patients presenting with ST‐elevation myocardial infarction: Outcomes from the pan‐London heart attack centers

Abstract Background The impact of COVID‐19 on the diagnosis and management of nonculprit lesions remains unclear. Objectives This study sought to evaluate the management and outcomes of patients with nonculprit lesions during the COVID‐19 pandemic. Methods We conducted a retrospective observational analysis of consecutive primary percutaneous coronary intervention (PPCI) pathway activations across the heart attack center network in London, UK. Data from the study period in 2020 were compared with prepandemic data in 2019. The primary outcome was the rate of nonculprit lesion percutaneous coronary intervention (PCI) and secondary outcomes included major adverse cardiovascular events. Results A total of 788 patients undergoing PPCI were identified, 209 (60%) in 2020 cohort and 263 (60%) in 2019 cohort had nonculprit lesions (p = .89). There was less functional assessment of the significance of nonculprit lesions in the 2020 cohort compared to 2019 cohort; in 8% 2020 cohort versus 15% 2019 cohort (p = .01). There was no difference in rates of PCI for nonculprit disease in the 2019 and 2020 cohorts (31% vs 30%, p = .11). Patients in 2020 cohort underwent nonculprit lesion PCI sooner than the 2019 cohort (p < .001). At 6 months there was higher rates of unplanned revascularization (4% vs. 2%, p = .05) and repeat myocardial infarction (4% vs. 1%, p = .02) in the 2019 cohort compared to 2020 cohort. Conclusion Changes to clinical practice during the COVID‐19 pandemic were associated with reduced rates of unplanned revascularization and myocardial infarction at 6‐months follow‐up, and despite the pandemic, there was no difference in mortality, suggesting that it is not only safe but maybe more efficacious.


| INTRODUCTION
The COVID-19 pandemic necessitated an unprecedented restructuring of clinical pathways in cardiac centers globally. In the UK, there was a significant reduction in elective admissions in an effort to create capacity lacking for COVID-19 patients. For interventional cardiology, this culminated in reduced capacity for elective procedures. 1 Concomitantly, patients with COVID-19 presenting with ST-elevation myocardial infarction (STEMI) were shown to have increased incidence and burden of thrombotic culprit lesions. 2 However, it is not known whether COVID-19 has impacted the diagnosis and management of nonculprit lesions. Of note, randomized trials involving more than 6300 patients over the last decade all agree that revascularization of noculprit lesions at STEMI is superior to medical therapy alone. 3 However, the role of coronary physiology in this setting for the assessment of nonculprit lesions remains unclear.
Recently, the FLOWER-MI study attempted to answer this question by utilization of coronary physiology to adjudicate stenosis severity in the setting of STEMI. It showed that there was no difference in the primary endpoint which was a composite of all-cause death, nonfatal myocardial infarction, or unplanned hospitalization leading to urgent revascularization at 1 year between fractional flow reserve (FFR)-and angiography-based management. 4 We hypothesized that the rate of interventional treatment of nonculprit lesions during the pandemic would be lower than it was beforehand, and that rate of coronary physiology utilization would decrease.

| Study design and patient population
We conducted a retrospective observational analysis of consecutive primary percutaneous coronary intervention (PPCI) pathway activations to all seven heart attack centers in London, UK. The PPCI programme in London is the largest urban network of seven heart attack centres in the UK using a single ambulance triggered service and providing 24/7 treatment for STEMI to a population of 9 million.

| Outcomes
The primary outcome was the rate of nonculprit lesion PCI and secondary outcomes included major adverse cardiovascular events (at 30 days and 6 months) and procedural timing and characteristics.
Major adverse cardiovascular events and all-cause mortality during STEMI-related hospitalization were determined from electronic patient records and discharge summaries. In addition, baseline demographic characteristics were also retrieved. All events are reported cumulatively at respective time points.

| Statistical analysis
Normality of data was assessed by the histogram, normal Q-Q plot, and Shapiro-Wilk test. Continuous normal data are expressed as mean ± standard deviation and compared using paired Student's t tests. Nonnormal data are expressed as median (interquartile range) and compared using the Mann-Whitney test. Categorical data were presented as numbers with percentages and compared using the χ 2 test. A p < 0.05 was deemed to be of statistical significance. Data analysis was performed using SPSS 27 (IBM Corp).

| RESULTS
A total of 788 patients undergoing primary PCI were identified, 348 during 2020 and 440 during 2019 study periods. Of these, 209 (60%) in 2020 cohort and 263 (60%) in 2019 cohort had nonculprit lesions (p = .89). No differences between 2019 and 2020 cohorts were identified in terms of baseline characteristics or the delays from onset of chest pain to the first call for help or door-to-balloon time (Table 1). However, first-call-to-door time was significantly longer in the 2020 cohort compared with the 2019 cohort (p = .001).
Nonculprit lesion characteristics were similar, including number, location, and severity of the lesion(s) ( Table 2). There was the less functional assessment of the significance of nonculprit lesions in the 2020 cohort compared to the 2019 cohort; a pressure wire or a noninvasive ischemia test was utilized in 8% 2020 cohort versus 15% 2019 cohort (p = .01) ( Table 1). There was no difference in rates of PCI for nonculprit disease in the 2019 and 2020 cohorts (31% vs.   This may have contributed to the reduction seen in PPCI activations worldwide in 2020. Fourth, its observational design includes potential selection bias due to a reduction in STEMI admission in 2020 compared to 2019, whereby higher-risk patients potentially did not make it to the hospital. Fifth, the relatively small size of the two cohorts with nonculprit lesions may have impacted findings in this study.
Finally, the outcome of those patients who did not present to the PPCI service is unknown. They may have significantly worse late outcomes, with heart failure, arrhythmia, and death as yet unmeasured in the community.

| CONCLUSION
In our study, changes to clinical practice during the COVID-19 pandemic were associated with reduced rates of unplanned revascularization and myocardial infarction at 6-months follow-up, and despite the pandemic, there was no difference in mortality, suggesting that it is not only safe but may be more efficacious. This could also have significant resource implications even beyond the pandemic.