Discussion
In this study, we have analyzed the outcomes of patients whose non-emergency cardiac intervention had been postponed due to the COVID-19 crisis. We found that the deferral of scheduled cardiac interventions was associated with increased emergency cardiovascular hospitalization or death in the first 365 days, suggesting the progression of disease. This hypothesis is substantiated by our finding of significantly more pronounced symptoms and significantly higher levels of cardiac biomarkers in the study group after 12 months of follow-up. Remarkably, subgroup analyses showed that patients suffering from valvular heart disease, rather than patients scheduled for coronary catheterization or an electrophysiological intervention, experience early emergency cardiovascular hospitalization if their non-emergency intervention is deferred.
Due to the rapidly rising numbers of SARS-CoV-2 infected in spring 2020, hospital resources had to be allocated to sustain IMC and ICU capacities. Consequently, cardiologic societies developed strategies to identify patients who are in a condition allowing to safely defer non-emergency procedures [
1,
3,
4].
For example, coronary artery disease patients were deemed suitable for initial medical treatment only in the presence of stable angina up to CCS class III [
1,
5]. Furthermore, the deferral of patients with severe aortic stenosis scheduled for transcatheter aortic valve implantation was felt appropriate for compensated patients with an aortic valve area above 0.5 cm
2 and without recent hospitalization [
1,
5]. Postponement of percutaneous mitral valve repair procedures was mostly accepted in the absence of recent heart failure hospitalization [
1,
5]. As for patients suffering from arrhythmic heart disease, most procedures were considered to be deferrable, except for immediate life-threatening conditions such as recurrent therapy-refractory ventricular tachycardia, battery replacement in the case of end-of-life in pacing dependency, or the extraction of infected devices [
1,
6]. However, recommendations vary depending on the publishing cardiac society.
In our study, we observed that deferred cardiac patients, despite being classified as postponable, show progression of symptoms and experience emergency hospitalizations significantly more often [
1]. In contrast, patients who underwent their intervention as scheduled showed an improvement of symptoms at the 12-month follow-up. These findings suggest that the current strategy to manage patients with cardiovascular disease during the COVID-19 pandemic needs refinement and, furthermore, underscores the difficulty of the task shouldered by cardiologic societies to develop general recommendations to avoid overburdened healthcare systems amidst the COVID-19 crisis, while preserving medical care for cardiac patients.
A study evaluating the number of hospitalizations for the different types of cardiac interventions during the first ‘wave’ of the COVID-19 pandemic showed declined interventions in all areas. While the authors observed a reduction in the weekly procedure rate of 20% for transcatheter aortic valve implantations and 28% for percutaneous coronary interventions, the number of pacemaker-, ICD- and CRT (cardiac resynchronization therapy)-implantations declined by approximately 45%. Remarkably, ablations for atrial fibrillation even dropped by more than 80% [
7]. These observations possibly reflect the recommendations of the cardiac societies which state that patients with arrhythmic heart disease rather than those with severe valvular heart disease are deferrable [
1]. However, studies evaluating the effect of prolonged waiting times on the patients’ course of disease, particularly taking into account the different types of heart disease, are sparse.
Since our study population comprised cardiac arrhythmia patients, patients with severe valvular heart disease and patients with ischemic heart disease, we performed subgroup analyses to evaluate which subgroup predominantly suffered from the prolonged waiting time. Intriguingly, we found that particularly patients with severe valvular heart disease experience early emergency cardiovascular hospitalization if their elective appointment is postponed, while we could not observe significant differences for both coronary artery disease and arrhythmic heart disease patients. These findings are in accordance with the literature.
With regard to arrhythmic heart disease patients, in general, non-emergency interventions for supraventricular tachycardia were considered as being deferrable, since their outcome is rather favourable [
1,
6,
8]. Even for patients with documented ventricular tachycardia, it has been demonstrated in the BERLIN VT trial that preventive ventricular tachycardia (VT) ablation before ICD implantation had not reduced mortality or hospitalization for arrhythmia [
9]. Interestingly, in the EU-CERT-ICD study, it has been shown that primary prophylactic ICD implantation had been associated with a 27% lower mortality rate [
10]. Nevertheless, recommendations did not classify primary prophylactic ICD implantation as either ‘urgent’ or ‘emergency’ and, thus, approved patients’ deferral during the COVID-19 crisis [
1]. However, the aforementioned interventions only comprised the minority of arrhythmic heart disease patients included in our study. Most patients were scheduled for catheter ablation for atrial fibrillation and were categorized as ‘lower priority’ during the COVID-19 pandemic [
1]. This recommendation is, for instance, referable to the intention-to-treat analysis of the CABANA trial where the authors could not detect a difference in mortality rates between patients undergoing catheter ablation and conservatively treated patients. In contrast, regarding the combined endpoint mortality or cardiovascular hospitalization, they observed a higher event rate in the drug-therapy-only group [
11]. In our study, we could only detect a trend towards higher hospitalization rates in patients whose rhythmological intervention had been cancelled. This might be related to the heterogeneity of the cardiac arrhythmia subgroup, their number and the limited follow-up period of 12 months. However, we observed that symptoms of dyspnoea, as measured by NYHA class, significantly increased in the study group and decreased in the control group, underscoring the beneficial effect of a timely rhythmological intervention. Nevertheless, the rather benign outcome suggests that it is possible and reasonable to reschedule non-emergency appointments of patients with arrhythmic heart disease during a pandemic depending on the trend of infection numbers.
Studies evaluating the outcome of coronary artery disease patients with stable angina showed that the outcome of stable CAD patients on a wait list or who are managed conservatively is rather benign [
12,
13]. For example, the ISCHEMIA trial demonstrated that an additional invasive intervention is not superior to medical therapy alone regarding both time-to-death and time-to-myocardial infarction [
13]. Therefore, stable CAD patients were considered as deferrable during the COVID-19 pandemic [
1,
3,
4]. Although we found that the symptoms of patients who underwent coronary catheterization as scheduled improved, and troponin T levels declined significantly compared to patients whose intervention had been postponed, we could not detect a difference in the primary outcome. Consequently, our results suggest that coronary catheterization procedures for patients with stable CAD can be postponed if necessary, however, at the cost of persistent angina pectoris symptoms.
As for patients with severe valvular heart disease, there have been reports that a longer waiting time leads to higher morbidity and mortality. Previous studies have shown that waiting times of 30–80 days are associated with mortality of 2–4.9% in patients scheduled for TAVI [
12,
14,
15]. Additionally, after a wait time of almost three months, about 12% of TAVI patients experienced heart failure hospitalization [
15]. In patients pending on percutaneous mitral valve repair, studies reported mortality rates of 8% after one and a half months and ≈10% after 180 days [
12,
16]. Furthermore, ≈50% of patients were hospitalized for heart failure after 180 days [
16]. Here, we demonstrate that patients with severe valvular heart disease are prone to an event of early emergency cardiovascular hospitalization if their non-emergency intervention is deferred. Since the 30-day and 60-day Kaplan–Meier event rates were 34.7% and 53.7%, respectively, our results suggest that especially the first few months following the deferral display the most critical phase in this population. Additionally, the significant increase in symptoms and NT-pro BNP levels during the wait time insinuates relevant disease progression. Consequently, our results substantiate the hypothesis that valvular heart disease patients are especially susceptible to adverse events and the progression of disease if heart valve repair or replacement is delayed, and, thus, might not be suitable for deferral during the ongoing pandemic.