Success in treating acute myocardial infarction with ST-segment elevation (STEMI) is time-dependent, requiring access to emergency services, prompt identification of the problem, and immediate medical intervention.¹ This cardiovascular event is one of the most severe pathologies, with high mortality and varying sequelae depending on the delay time to intervention.² Only 20% of patients with acute chest pain reach the emergency department within 2 hours of symptom onset.³

At the onset of the COVID-19 pandemic, patients with significant risk factors for cardiovascular diseases faced difficulties seeking medical attention due to the increased risk of severe virus infection. Fear of COVID-19, the implementation of lockdowns, and a shift in healthcare priorities influenced the entire chain of organization for cardiovascular emergencies.⁴ Additionally, it is important to note the potential exacerbating effect of COVID-19 on cardiovascular diseases and the psychological impact generated by isolation.

The lack of knowledge about the changes brought about by COVID-19 in cardiovascular diseases can have a negative impact on already known complications. Thus, new studies are needed to understand how the pandemic has modified healthcare, aiming for constant improvements in service. The objective of this study was to analyze the clinical profile, delay times, and clinical outcomes of patients with STEMI undergoing primary percutaneous coronary intervention (PPCI) before and during the COVID-19 pandemic.

A total of 157 patients were initially included. Ten patients were excluded for undergoing cardiac catheterization in a non-urgent fashion (1 excluded during the pre-pandemic period and 9 during the pandemic period). Thus, the final sample consisted of 147 patients, comprising 40 (27.2%) in the pre-pandemic period, 17 (11.5%) in pandemic I, and 90 (61.2%) in pandemics II and III combined. Only 5 patients were concurrently diagnosed with COVID-19 during the STEMI episode (4 cases in pandemic I and 1 in pandemic II). Overall, 100 patients (68.0%) had a prior diagnosis of arterial hypertension, and a higher prevalence of this risk factor was observed among patients affected during pandemic I. There was no significant difference in the prevalence of other risk factors between the compared periods (Table 1).

Table 1

Clinical variables	Pre-pandemic	Pandemic I	Pandemic II	Pandemic III	p value (p1 / p2)*
Male, n (%)	28 (70%)	11 (64.7%)	19 (65.5%)	43 (70.4%)	0.6 / 0.7
Female, n (%)	12 (30%)	6 (35.3%)	10 (34.4%)	18 (29.5%)	0.6 / 0.7
Age, n	62.2	65.9	58.9	60.4	0.9 / 0.9
Arterial hypertension, n (%)	29 (72.5%)	16 (94.1%)	20 (68.9%)	35 (57.3%)	0.05 / 0.004
Diabetes mellitus, n (%)	10 (25%)	7 (41.1%)	11 (37.9%)	18 (29.5%)	0.2 / 0.1
Dyslipidemia, n (%)	14 (35%)	6 (35.2%)	9 (31%)	15 (24.5%)	0.9 / 0.46
Chronic kidney failure, n (%)	1 (2.5%)	0	1 (3.4%)	3 (4.9%)	0.7 / 0.49
Current smoking, n (%)	17 (42.5%)	5 (29.4%)	9 (31%)	13 (21.3%)	0.15 / 0.2
Previous smoking, n (%)	5 (12.5%)	1 (5.8%)	2 (6.8%)	9 (14.7%)	0.31 / 0.28

*p1: Comparison of clinical variables between pre-pandemic and pandemic I; p2: Comparison between pandemic I and the sum of pandemic II and pandemic III. * p: chi-square test and Fisher’s exact test.

There was a trend towards an increase in delta T (time from symptom onset to PPCI), onset-to-door time, and FMC-to-balloon time during pandemic I; however, statistical significance was not reached. On the other hand, door-to-balloon time exhibited a more uniform behavior across the analyzed periods (Figure 1).

Figure 1 FMC: first medical contact.

Throughout the pandemic, there was a decrease in the occurrence of cardiopulmonary arrest during the PPCI procedure, following an initial increase in this outcome during pandemic I. In-hospital mortality increased significantly from the pre-pandemic period to pandemic I. The intraprocedural complications and clinical outcomes are detailed in Table 2.

Table 2

Complications and outcomes	Pre-pandemic	Pandemic I	Pandemic II	Pandemic III	p value (p1 / p2)*
No reflow, n (%)	2 (5%)	3 (17.6%)	1 (3.4%)	6 (9.83%)	0.12 / 0.14
Acute stent thrombosis, n (%)	0	1 (5.8%)	0	0	0.29 / 0.15
Atrioventricular block, n (%)	0	0	0	4 (6.5%)	NA / 0.49
Cardiogenic shock, n (%)	0	0	2 (6.8%)	1 (1.6%)	NA / 0.59
Cardiorespiratory arrest during procedure, n (%)	1 (2.5%)	3 (17.6%)	2 (6.8%)	1 (1.6%)	0.06 / 0.04
Death during procedure, n (%)	0	1 (5.88%)	0	0	0.29 / 0.15
Procedure success, n (%)	37 (92.5%)	14 (82.3%)	28 (96.5%)	58 (95%)	0.18 / 0.06
Acute renal failure, n (%)	6 (15%)	3 (17.6%)	3 (10.3%)	2 (3.2%)	0.28 / 0.09
In-hospital death, n (%)	2 (5%)	5 (29.4%)	5 (17.2%)	6 (9.8%)	0.01 / 0.05

*p1: Comparison of clinical variables between pre-pandemic and pandemic I; p2: Comparison between pandemic I and the sum of pandemic II and pandemic III. * p: chi-square test and Fisher's exact test.

This study assessed the impact of the COVID-19 pandemic on delay times and clinical outcomes of patients with STEMI undergoing urgent cardiac catheterization and PPCI. It is well established that delay time until reperfusion significantly influences the clinical outcomes of these patients, and prolonged delays are associated with a higher likelihood of complications. We observed a trend toward increased delay times, particularly delta T, onset-to-door time, and FMC-to-balloon time during the initial COVID-19 outbreak compared to the pre-pandemic period, along with a significant increase in mortality. Several indirect and direct effects have been advocated to explain the increased in-hospital mortality associated with SARS-CoV-2 positivity in patients presenting with STEMI. Among the indirect effects, the fear of contagion may have affected patients’ willingness to present to hospital, resulting in a substantial delay in cardiac catheterization laboratory activations. Similar findings were observed in other studies, as a longer door-to-balloon time in SARS-CoV-2–positive patients with STEMI, reflecting the in-hospital delay. This has been attributed, especially during the first part of the pandemic, to the different triaging systems for STEMI patients suspected of COVID-19, to the use of COVID-19–dedicated pathways, and to the time spent donning personal protective equipment.⁵

The prolongation of these times may be linked to factors such as patients delaying seeking hospital services from the onset of symptoms due to fear of contamination, as well as delays in the healthcare system’s response. Although the reason for the delay was not investigated in this study, these data suggest challenges in adapting to manage the system amidst the global outbreak.⁶ One of the findings of our study was the high percentage of procedures performed during weekends and after business hours: 82.5% in the pre-pandemic period, 64.6% in pandemic I, 89.2% in pandemic II, and 70.4% in pandemic III. According to a meta-analysis, patients who presented outside of business hours were less likely to undergo PPCI within 90 or 120 minutes after FMC. A longer delay was observed from chest pain to the first contact with medical services until coronary angiography was performed. PPCI for STEMI performed outside working hours may be associated with higher periprocedural mortality compared to procedures performed during regular working hours. The longer delay in transferring patients outside business hours may partially account for this finding.⁷

During the early phase of the pandemic, there was an estimated 38% reduction in procedures across 9 interventional centers in the United States.⁸ Xiang et al. reported a 62% reduction in the number of procedures performed in China during the pandemic, and a 40% reduction was noted in an analysis of 73 centers in Spain.^8,9 Reporting this analysis to our environment, it can be said that there was a decrease in elective cariological procedures, which could therefore provide an increase in the treatment of acute cases.¹⁰

Another possibility is that later presentation during pandemic I led to more severe clinical conditions, hence a higher risk of complications and death. Patients who initially refrained from seeking medical attention, likely due to the fear of contracting the infection in the hospital setting, probably presented to the hospital later and in a worse clinical condition.¹¹ Additionally, it is possible that, at the beginning of the pandemic, many patients with less severe clinical presentations avoided seeking medical attention due to fear of COVID-19,¹² thus selecting more severe patients actually treated during this period. Regarding the healthcare system, the protocols adopted by hospitals to minimize the chances of coronavirus spread may have resulted in delays in the transfer and diagnosis processes of STEMI.

The door-to-balloon time remained stable in the various analyzed periods, indicating the team’s attention to STEMI care protocols at the institution. Public education and systems-level changes might be crucial in minimizing total myocardial ischemia time and improving healthcare of patients with STEMI during the COVID-19 pandemic.¹³ However, concerning the increase in in-hospital deaths, occurrences of cardiopulmonary arrest, and complications during PPCI, one may conclude that they likely represent a consequence of delays in other points of care, including the patients’ delay in seeking urgent care, as well as the poorer clinical condition (Central Illustration). A shorter time until opening the culprit artery in STEMI remains crucial for reducing mortality and preserving myocardial viability.¹⁴

The higher proportion of patients with COVID-19 is another presumed cause of increased severity in STEMI at the beginning of the pandemic. It is known that the virus has direct cardiovascular effects, with myocardial injury occurring in 8% to 12% of COVID-19 cases. Direct myocardial injury, systemic inflammation, imbalance between myocardial oxygen supply and demand, hypercoagulability, and endothelial dysfunction seem to be the most common mechanisms responsible for cardiac injuries.¹⁵ The high incidence of acute renal failure during this period may also be partially driven by the repercussions of the viral infection. A systematic review with meta-analysis¹⁶ conducted with 2,266 patients showed increased rates of acute renal failure and vascular complications among patients undergoing PPCI during the COVID-19 pandemic. However, the direct action of the COVID-19 virus does not seem to have been the primary cause of the worse outcomes in pandemic I, as fewer than a quarter of patients had a confirmed diagnosis of the infection. Thus, the main reason we find to explain this outcome is the worse clinical setting and, probably, higher incidence of contrast-induced nephropathy.

We must acknowledge some study limitations, mainly the small sample size and the retrospective nature, which hinder a broader analysis and comparison of outcomes during different periods. Possible information biases are inherent to this type of study, especially regarding the time of onset of clinical symptoms. These characteristics, along with the dynamic nature of sanitary conditions in different locations throughout the COVID-19 pandemic, limit the generalizability of these data. Although the study representativeness is single-center, it is essential to note that it was conducted at a local reference service, receiving the majority of its STEMI patients referred by the Mobile Emergency Care Service, which may significantly impact delay times and generate influence from multiple non-measurable variables.

There was a trend towards an increase in delta T, onset-to-door time, and FMC-to-ballon time during the pandemic compared to the pre-pandemic period, reflecting greater delays at various levels of assistance for STEMI before reaching the referral service. There was a significant increase in in-hospital mortality for STEMI at the onset of the pandemic, with a tendency to decrease over time, but not returning to pre-pandemic levels. This study is of great relevance to reaffirm the importance of minimizing delays in the diagnosis and treatment of STEMI and to highlight the impact that the COVID-19 pandemic had on patients in the context of this disease.