This retrospective observational single-center study collected data from all the consecutive patients with chronic coronary syndromes who underwent elective PCI from October 2019 to November 2020 (1-year) in Hospital de Braga.

Patents who qualified SDD were defined by an approved institutional protocol that includes low risk clinical characteristics and favorable angiographic and sociodemographic criteria (Fig. 1).14 However, the interventional cardiologist could individualize management of the patient, based on professional knowledge and opinion.

Fig. 1.

Institutional protocol of outpatient elective percutaneous coronary intervention. CCS, chronic coronary syndrome; Cr, creatina; CrCl, creatine clearance; ECG, electrocardiogram; ID, identification; INR, international normalized ratio; LVEF, left ventricular ejection fraction; PCI, percutaneous coronary intervention.

Most patients undergoing PCI at our center stayed in a 4-bed recovery room immediately after the procedure and were afterwards transferred according to the stablished course: (a) day hospital room (3-bed plus sitting capacity) for SDD or (b) admitted in the ward for overnight stay (ONS).

Data was collected from the catheterization laboratory dedicated digital database and from patients’ medical records. Demographics and clinical characteristics were assessed. Procedural, peri-procedural and 30-day follow-up data was also collected.

Primary endpoint was a composite of adverse events (all-cause mortality, acute coronary syndrome, stent thrombosis, re-intervention, major bleeding, stroke, contrast-induced renal failure, vascular access complications) at 30 days.

Descriptive statistics included means (± standard deviation) or median [interquartile range] for continuous variables and absolute and relative frequencies for categorical variables.

Continuous variables were compared with independent samples Student t test for parametric variables, or Mann–Whitney U test for non-parametric distribution. Categorical variables were compared using Chi-square test or Fisher's exact test, as appropriate.

Statistical significance was established at a P<.05 for all tests. Statistical analysis was performed using SPSS (version 25).

All patients gave informed consent for the procedure executed. Confidentiality and anonymity of all collected data were ensured during all phases of the study. This study was approved by the local ethics committee and comply with the provisions of the Helsinki Declaration.

The manuscript has been submitted following the STROBE (Strengthening the Reporting of Observational Studies in Epidemiology) recommendations.

This study included 147 patients, 76% males with a mean age of 66±10, that underwent elective PCI during the first year after implementation of SDD protocol. Most patients undergoing elective PCI in the center were discharged in the same day (n=94, 64%).

Table 1 shows the baseline characteristics of patients submitted to elective PCI and the comparison between SDD and ONS. Clinical characteristics such as age, sex and risk factors were balanced between the 2 groups. Previous history of acute coronary syndrome was more frequent in ONS when compared to SDD (38% vs 19%, P=.01). Left ventricular dysfunction (<40%) was more frequent in ONS patients (17% vs 6%, P=.04). Lastly, SDD patients were more often submitted to a stress test before elective PCI when compared to ONS (77% vs 58%, P=.02), mostly due to a significantly higher percentage of exercise electrocardiogram in this group (34% vs 17%, P=.03).

Table 2 presents the procedural characteristics of patients submitted to elective PCI. The percentage of radial access did not differ between groups, with high percentages of radial access in the population analyzed (SDD-PCI: 100% vs ONS: 98%, P=.54). Patients admitted after elective PCI had higher Syntax I score (10 points [6–16] vs 8 points [5–12]; P=.01), were more frequently submitted to multivessel PCI (24% vs 6%, P<.01), had a higher surrogate for longer procedures – fluoroscopy time (11min [7–15] vs 8min [5–13]; P=.02) and higher post-procedural troponin I measurements (0.32ng/mL [0.1–1.1] vs 0.03ng/mL [0.02–0.05]; P<.01) when compared to SDD-PCI. Contrast volume, use of pressure wires and intracoronary imaging did not differ between groups.

Target vessel differences in single-vessel angioplasties were not detected (Table 2). A minority of patients was submitted to procedures on chronic total occlusion, and all were admitted for ONS (n=3; 2%). Only 2 patients (1%) had intervention on in-stent restenosis and were both admitted in the ward. Bifurcation lesions were well-balanced between ONS and SDD patients (41% vs 60%, P=.60), all treated with 1 stent technique. Unsuccessful procedures were rare and occurred exclusively in the ONS group (n=4; 8%). Among the patients, 5 (3%) experienced small dissections and were therefore admitted for surveillance.

Ambulatory patients were discharged after a mean surveillance period of 290±54min. Out of 113 patients meeting protocol criteria (76% eligibility), only 93 (64%) were discharged on the same day. Table 3 outlines reasons for ONS in this group of patients, with main causes being operator preference (56%, n=11) and thoracic pain during the procedure (27%, n=5).

There were no adverse events (mortality, acute coronary syndrome, stent thrombosis, re-intervention, major bleeding, stroke, contrast-induced renal failure, vascular access complications) during the 30-day follow-up period in the SDD regimen.

First, this non-randomized observational single-center study analyzing a singular protocol for SDD-PCI. Therefore, a highlighted limitation is the study's low sample size, exacerbated by a lower total number of angioplasties performed during the COVID-19 pandemic period compared to previous years.

Furthermore, the absence of events in the early discharge group was excepted due to exclusion criteria in this group and to the possibility of interventional cardiologists to vary the group assignment based on post-angioplasty evolution. Additionally, the fluoroscopy time and Syntax score are very low, indicating procedures of low complexity and, therefore, a specific selection of candidates. This may impact the external validity of the study.

Moreover, we solely present the follow-up data for SDD-PCI patients, as the comparison with ONS is unviable, given that these groups are intrinsically different and again reflect the selection of lower risk patients for SDD and higher risk patients for ONS.

Lastly, it is important to note that the implementation of the protocol coincided with the COVID-19 pandemic, potentially impacting strategy selection based on available hospital bed capacity.