COVID-19, caused by the severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2), is a highly contagious condition that may lead to serious respiratory illness and premature death; with up to 20% of hospitalized patients requiring mechanical ventilation and intensive care.1,2 The first cases were reported in December 2019 in Wuhan, Hubei, China but rapidly spread worldwide, being declared as a pandemic by the WHO on 11 March 2020.3 Currently, there are about 34 million cases, with more than 1 million deaths globally.4

In order to contain the COVID-19 pandemic, there was a widespread lockdown worldwide, with restrictive home confinement and social distancing measures.5,6 Overwhelmed healthcare systems were also promptly restructured, expanding intensive care units and altering or cancelling non-essential procedures.7,8

In the meantime, many countries reported a significant reduction in hospital admissions for several acute conditions that require life-saving evidence-based emergent treatment, such as acute coronary syndrome (ACS) and stroke.9–20 Moreover, patients with cardiovascular disease are at increased risk of severe COVID-19 illness, endorsing the direct and indirect consequences of delayed care of this particular group of patients.21–23 In Portugal, the first case was reported on 2 March 2020 in Porto. The mandatory national lockdown was imposed from 18 March to 2 May, amounting to 25 190 cases and 1023 deaths due to COVID-19 at the end of this period. The northern region of Portugal, mainly Porto's metropolitan area, had the highest incidence of COVID-19 cases, reaching around 14 951 cases and 585 deaths.24–27

The aim of this study was to assess the impact of the COVID-19 pandemic on ACS admissions to the Cardiology Department of the Centro Hospitalar Universitário de São João, a tertiary care hospital in Porto's metropolitan area.

This retrospective, case-controlled study included all patients admitted to the Cardiology Department of Centro Hospitalar Universitário de São João with a diagnosis of ACS, during the months of March and April of 2020 (pandemic group) and in the same period of 2019 (control group). Patients who tested positive for SARS-CoV-2, and therefore admitted to COVID-19 exclusive units, were also included.

The database used in this study was completed retrospectively using the available clinical records. Patients were selected based on the final diagnosis at the time of discharge (ST-segment elevation myocardial Infarction (STEMI), non-ST-segment elevation myocardial infarction (NSTEMI) or unstable angina (UA)). ACS was defined according to the Fourth Universal Definition of Myocardial Infarction.28

Demographic characteristics (gender, age, presence of cardiovascular risk factors, chronic kidney disease, previous vascular events and LV dysfunction), in-hospital clinical course (length of stay, Killip class, maximum troponin value, complications, prevalence of left ventricular (LV) systolic dysfunction at discharge), and short term mortality were compared between groups. Continuous variables were summarized as mean ± standard deviation or median (25, 75 percentiles) and categorical variables as proportions. Groups were compared using Student's t tests, Wilcoxon Rank Sum tests, and χ2 tests, as appropriate. Values of p<0.05 were considered significant. All statistical analyses were performed using IBM SPSS statistics 25 (New York, United States).

In the early COVID-19 pandemic, the number of patients requiring hospitalization and intensive care overwhelmed the healthcare facilities in numerous countries. Meanwhile, a major decline in hospital admissions with ACS in several medical centers was observed, possibly due to the quarantine and other large-scale public health measures.9–17 Some centers in highly affected regions, like Northern Italy and China, implemented early fibrinolysis protocols in STEMI treatment, with a direct decrease in the number of primary PCIs.32,33 Afterwards, position statements reinforced that during the COVID-19 pandemic, the standard of care for STEMI patients at PCI-capable hospitals remained primary PCI when it could be provided in a timely manner.29–34 During the first phase of the COVID-19 pandemic in Portugal, the population of Porto and the surrounding urban area was the most affected by SARS-COV-2 disease. Contrary to what was seen in other countries, we did not see a clear reduction in hospitalization but presentations were more severe, with a larger proportion of STEMIs, higher maximum troponin values and greater prevalence of LV systolic dysfunction at discharge. The fear of becoming infected by SARS-Cov-2 may have discouraged patients that experienced milder symptoms to seek urgent medical care. In fact, previous studies in other countries noted a deferred search for urgent medical care during the pandemic.17,29 Although not statistically significant, our data suggests that there was a delay between the onset of symptoms and search for medical care during the pandemic. The non-significance of this finding may be related to the small sample size. This delay may explain the larger number of STEMIs admitted and consequently the higher prevalence of LV systolic dysfunction at the time of discharge. It is of relevance that during the pandemic there was a significantly higher prevalence of atherosclerosis among patients and this may have had some impact on the differences seen in the outcomes of the two groups.

In-hospital and 30-day mortality were numerically higher in patients admitted during the pandemic, similar to those observed in other studies.15 Our study was innovative since it also assessed complications related to ACS; the rate was overall low but a higher proportion of complications occurred during the pandemic. This may translate into higher mortality and higher morbidity in the near future. Our concern also extends to patients that did not reach out for medical care during the pandemic, which may negatively affect long-term cardiovascular health. This may partially explain the higher revascularization rates, since milder cases may not have come to medical attention. More studies should be designed to explore these events.

Importantly, there was no evidence of significant delay in the healthcare response to STEMI patients, including in cases initially admitted to hospitals without the ability to perform primary PCI. Revascularization rates were not precluded and fibrinolysis use was residual. These data may be explained since Portugal did not reach a situation in which the health care system was overwhelmed or began to collapse.34

This analysis has some limitations. Only patients admitted to one center were included. Additionally, acute morbidity and mortality may be underestimated, since patients who died in the pre-hospital phase/emergency room or were admitted at other intensive care units were not included.

During the lockdown phase of the COVID-19 pandemic, there were fewer admissions for ACS but more serious presentations in a tertiary hospital center in the region most affected by COVID-19 in Portugal, possibly due to a deferred search for healthcare by the population. As ACS requires prompt in-hospital assessment and treatment in order to prevent significant morbidity and mortality, the general population should be made aware of this problem. Also, a public healthcare safety message addressing non-COVID emergencies must be transmitted. The global healthcare policy focused on addressing the current pandemic must not disregard other serious medical emergencies. More studies are needed to assess the long term repercussion of the COVID-19 pandemic in acute cardiovascular patients.

The authors have no conflicts of interest to declare.