Outcomes of Patients Undergoing Elective Percutaneous Coronary Interventions in the Ambulatory Versus In-Hospital Setting

Abstract: Objectives. To compare outcomes of elective percutaneous coronary interventions (PCI) in same-day discharge and overnight hospital stays. Background. Advances in PCI techniques and equipment have allowed same-day discharge after elective PCI. In this study, we investigated the safety of same-day discharge ambulatory PCI in patients according to age, creatinine, and ejection fraction (ACEF) scores. Methods. The ambulatory PCI group consisted of all PCIs with same-day discharge, while the overnight-stay group consisted of all elective PCIs with in-hospital observation and discharge the following day. Patients were stratified into tertiles based on ACEF score: low (<1.08), mid (≥1.08 and <1.31), and high (≥1.31). The primary endpoint was 30-day major adverse cardiac events, defined as readmission, all-cause mortality, non-fatal myocardial infarction, and target lesion revascularization. Propensity score matching was done to evaluate outcomes based on similar baseline characteristics. Results. There were 16,407 elective PCIs, of which 21.2% were in the ambulatory group. Patients who stayed overnight had similar 30-day composite outcomes as their same-day discharge counterparts in the high ACEF score (odds ratio [OR], 1.213; 95% confidence interval [CI], 0.625-2.355; P=.57) and mid ACEF score (OR, 0.636; 95% CI, 0.356-1.134; P=.13) comparisons, but had worse outcomes in the low ACEF score comparison (OR, 1.867; 95% CI, 1.134-3.074; P=.01). Conclusions. In this single-center registry, patients who underwent same-day discharge ambulatory PCI had no worse outcomes, and in some cases better outcomes, than overnight-stay patients; this result was found in the group as a whole, as well as in all ACEF score subcategories.

J INVASIVE CARDIOL 2014;26(3):106-113

Key words: ambulatory PCI, complications, elective PCI, same-day discharge 

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Close to 1 million percutaneous coronary interventions (PCIs) are performed in the United States (US) annually, with health-care costs approaching $10 billion.^1,2 With an overall aging population, there are increasing demands for fewer hospital beds. Advances in surgery have resulted in day surgery as the standard of care for many surgical procedures, such as cholecystectomy and transurethral prostatectomy.^3,4 Likewise, substantial advances in interventional cardiology techniques and equipment have allowed same-day discharge for elective PCI procedures. 

The Early Discharge After Transradial Stenting of Coronary Arteries (EASY) study was one of the first to show the safety and non-inferiority of same-day home discharge after uncomplicated coronary intervention in patients receiving abciximab and transradial PCI.⁵ The safety and non-inferiority of same-day discharge were extended to patients receiving transfemoral PCI in the Elective PCI in Outpatient Study (EPOS).⁶ This study suggested that in a select patient population, PCI by femoral approach does not lead to additional complications of death, myocardial infarction, coronary bypass graft surgery, repeat PCI, or puncture-related complications within 24 hours. An analysis of consecutive same-day discharges of 2400 patients at one center showed very low rates of major adverse cerebral events (0.33%), Thrombolysis in Myocardial Infarction (TIMI) minor bleeding (0.58%), and pseudoaneurysm (0.04%).⁷

Despite the initial demonstration of the feasibility and safety of post-PCI same-day discharge in a select patient population, there are few data that examine outcomes for patients stratified by baseline risk. In part, this may be due to the increasing number of scoring systems. The age, serum creatinine, and left ventricular ejection fraction (ACEF) score uses a simple, validated scoring tool that predicts mortality risk in elective cardiac operations, with higher scores denoting a higher risk.⁸ The ACEF score has also been used to stratify risk in patients undergoing PCI with respect to mortality and risk of myocardial infarction.⁹ In this study, we describe and compare the overall outcomes for patients undergoing elective same-day discharge PCI versus those admitted for overnight observation post PCI, and also examine outcomes for various ACEF scores.

Methods

Study design and patient selection. This was a retrospective study of all elective PCIs. The cardiac catheterization laboratory, as part of routine care, maintains a database of all patients who receive PCI with 30-day follow-up to assess for subsequent outcomes. Available data included patient demographics, medical history, medication use, laboratory findings, procedural findings, and cardiovascular outcomes. All standards of the institutional review board (IRB) were met by this study. 

All elective PCIs with follow-up data during the study period of January 1, 2003 to March 31, 2011 were included. For patients with multiple PCIs, all data were included as long as a repeat PCI did not fall within the 30-day follow-up period. The only exclusion criteria were a lack of prior echocardiogram for ejection fraction estimation, lack of serum creatinine measurements, and lack of follow-up data. Ambulatory PCI was defined as PCI with same-day discharge, whereas overnight-stay PCI was defined as an outpatient elective PCI in which the patient was admitted post PCI and discharged the following day.

Endpoints. The primary endpoint of this study was a 30-day composite of readmissions, non-fatal myocardial infarction (MI), death from any cause, and target lesion revascularization (TLR). TLR was defined as a repeat PCI of the original lesion site. Secondary endpoints included 30-day outcomes of individual cardiovascular components, bleeding events, development of a hematoma, and development of a pseudoaneurysm. The bleeding endpoints were comprised of TIMI major and minor bleeding.¹⁰

Laboratory assessments. All patients had venous blood samples obtained on the day of PCI. Serum creatinine and the most recent echocardiogram were used to calculate the ACEF score, which was defined as age/left ventricular ejection fraction + 1 (if creatinine >2 mg/dL). 

Statistical analysis. PCI data over the entire cohort were divided into tertiles reflecting patient ACEF scores: low (<1.08), mid (≥1.08 and <1.31), and high (≥1.31). Results are reported as mean ± standard deviation for continuous variables and as percentages for categorical variables. Baseline characteristics were compared with Pearson chi-square or Student’s t-test as appropriate. Outcomes were assessed by using a multivariate logistic regression analysis, and odds ratios with adjusted P-values are reported. Initially, univariate logistic regression modeling was used to define characteristics that were significant with P<.10, which were subsequently entered into the multivariate analysis. An additional analysis was done with propensity score matching in order to create a cohort with similar baseline characteristics with similar ACEF scores and for evaluation of the relationship between the type of PCI and outcomes. Propensity score was done by using a nearest neighbor algorithm with a 1:1 match, no replacement, and ±0.03 caliper.

Results

There were 16,407 elective PCIs during the study period with follow-up data. Of these, 3479 were ambulatory PCIs and 12,928 were PCIs with overnight hospital stays. Table 1 shows the baseline characteristics of the groups and Table 2 shows catheterization information. The groups were similar across various ACEF scores, although in the high ACEF groups, age was the factor that increased the ACEF scores in the overnight-stay group, while elevated creatinine and depressed left ventricular ejection fraction did so in the ambulatory group. Most patients underwent catheterization via femoral approach. Patients with complex catheterizations (such as left main coronary artery interventions, multiple interventions, or complications during the procedure) were more likely to stay overnight. 

Thirty-day cardiovascular outcomes. Patients who had post-PCI overnight stays had similar 30-day composite outcomes vs their ambulatory counterparts in the high ACEF score (odds ratio [OR], 1.213; 95% confidence interval [CI], 0.625-2.355; P=.57) and mid ACEF score (OR, 0.636; 95% CI, 0.356-1.134; P=0.13) comparisons, but had worse outcomes in the low ACEF score comparison (OR, 1.867; 95% CI, 1.134-3.074; P=.01). Additionally, there were no differences in hospitalizations, death, non-fatal MI, and TLR for ACEF tertiles, although there were no 30-day MI and TLR events for ambulatory PCI in the high ACEF score group and no 30-day deaths for ambulatory PCI in the low ACEF score group (Table 3). For the total cohort, there were fewer TLRs in the ambulatory group when compared to the overnight-stay group (OR, 2.851; 95% CI, 1.179-6.894; P=.02).

Thirty-day bleeding outcomes. Bleeding outcomes were low regardless of ACEF score and type of PCI. For all ACEF score comparisons, there were no differences in TIMI major or minor bleeding events, hematoma formation, GI bleeding, and other types of bleeding, except for the formation of pseudoaneurysm. There was a statistically higher incidence of pseudoaneurysm formation in the ambulatory PCI group for mid ACEF scores (0.7% vs 0.2%; OR, 0.166; 95% CI, 0.042-0.657; P=.01), high ACEF scores (0.4% vs 0.1%; OR, 0.118; 95% CI, 0.017-0.795; P=.03) and the total cohort (0.2% vs 0.1%; OR, 0.236; 95% CI, 0.082-0.683; P=.01), but no difference in low ACEF scores. For mid and high ACEF scores, there was no statistically significant difference in any other bleeding outcome between groups. 

Analysis of primary endpoint for ambulatory PCI and the total cohort. A univariate analysis (Table 4) was performed to assess the independent predictors of the primary endpoint in the ambulatory PCI group and in the total PCI cohort. The presence of chronic obstructive pulmonary disease was the only baseline characteristic independently associated with an increased risk of the primary endpoint, while an intervention on the left main coronary artery or multiple interventions per catheterization increased the risk of the primary endpoint. For the total cohort, an ACEF score of >1.31 was the only baseline characteristic that was independently associated with an increased risk of the primary endpoint, whereas an intervention on a bifurcation lesion or multiple interventions per catheterization were associated with a greater risk of the primary endpoint.

Propensity score matching. In the propensity-matched population, which included 2993 patients in each group, patient and procedure characteristics are shown in Table 5. Mean ACEF scores were 1.16 in both ambulatory PCI and overnight PCI groups. As shown in Table 6, overnight PCI was not associated with a decreased risk of the primary endpoint when compared to ambulatory PCI (OR, 1.025; 95% CI, 0.661-1.590; P=.91). For secondary cardiovascular endpoints, there was no difference between groups. Bleeding events were low between groups, with 1 TIMI minor bleeding event, 1 gastrointestinal bleeding event, and 2 other bleeding events. 

Discussion

This is the largest study to date looking at outcomes of ambulatory patients compared to in-hospital patients stratified by ACEF score at a high-volume center. The main findings of the present studies are as follows: (1) independent of ACEF score, patients with same-day-discharge did not have an increased risk for 30-day readmission, all-cause death, non-fatal MI, and TLR compared to patients who were admitted as inpatients post PCI; (2) patients with the lowest ACEF scores performed better than their overnight counterparts; and (3) adverse outcomes are rare even in the highest ACEF score patients. 

The current standard of care for patients undergoing uncomplicated elective PCI is an overnight stay for observation.¹¹ The most common complications in the first 48 hours after PCI include periprocedural MI, abrupt vessel closure, bleeding, acute stent thrombosis, and renal failure.¹² Advances in stents, antithrombotics, and arterial closure devices have increased the feasibility and safety of same-day discharge post PCI. The Society for Cardiovascular Angiography and Interventions has proposed criteria for patients eligible for same-day discharge post PCI.¹¹ Our institution uses similar criteria based on these guidelines (Table 7) with excellent safety endpoints, although as shown in this study, some criteria may not be necessary for overnight hospitalization, such as creatinine level and ejection fraction.⁷ While many trials have involved a transradial approach^5,11,13-19 for same-day discharge post PCI, most of our patients had transfemoral access, which in general portends a higher risk of vascular complications. Despite this, we report a very low vascular complication rate of 0.2% pseudoaneurysms and 0.08% hematomas. Our vascular complication rate is lower than those reported in previous studies.^6,19 This may be due to fixed heparin dosing and reliance of IIb/IIIa inhibitors in those studies and the use of bivalirudin in the majority of our patients. 

One surprising finding was that patients with the lowest ACEF scores with same-day discharge performed better than their overnight-stay counterparts. This may be due to operator judgment leading to bias, since patients who underwent more complex interventions had more complex angiography, or had complications that may have been sent to stay overnight for observation. However, in the mid and high ACEF cohorts, there was no significant difference in events, except in the formation of pseudoaneurysms, which was higher in the same-day discharge group. Also, in a propensity-matched cohort, there was no significant difference in the primary endpoint between the two groups collectively. While many may instinctively want to observe higher ACEF score patients because of fear of complications, our data do not support this.

The recent SCAI/ACC guidelines for same-day discharge post PCI are largely based on expert consensus and studies outside the US. They also are heavily based on studies that used transradial approaches, which have less risk for bleeding complications.^5,6,19 There may be some reluctance to adopt these guidelines because of this. In a study by Rao et al, only 1.25% of older patients had same-day discharge post PCI.¹² Our study is based on mainly transfemoral PCI at a high-volume US medical center with the heavy utilization of bivalirudin and vascular closure devices. Even in the highest-risk patients who were discharged, the composite event rate was low at 1.8%, which was mainly driven by repeat hospitalization of 1.6%. Our study’s findings mirror those of Muthusamy et al, who showed that their same-day discharge patients had a very low event rate of 0.5% using similar criteria for in-hospital admission.²⁰ Their study also had a relatively low number of low-risk patients at 12.1%. A recent meta-analysis of 12,803 patients showed similar findings that the event rate of death, MI, and TLR was statistically non-significant between same-day discharge and overnight-stay patients.²¹

In the current US health-care environment, cost-saving measures are going to be inevitable. An analysis by Rinfret et al showed significant savings with same-day discharge PCI.²² This was mainly due to the costs associated with an overnight stay. If half of the 1 million PCIs performed in the US were eligible for same-day discharge, it is estimated that this could result in a savings between $200 and $500 million using marginal cost and observation according to one analysis. 

Study strengths and limitations. Our study is a retrospective single-center experience at a high-volume academic medical center. We have safely adopted same-day discharge PCI for several years already using our institutional criteria. We studied a large cohort of patients across different ACEF score classes and showed no significant differences in major clinical outcomes, with low event rates.

There are some limitations to our study. It was retrospective and not randomized; the decision to either admit the patient for observation or to discharge the same day was left to operator discretion. This likely led to proportionally more patients in the same-day discharge group with low ACEF scores and comparatively more patients with mid and high ACEF scores in the overnight-stay group, since operators perceived those with higher-risk features to require observation. There were additional biases in the selection process for overnight stays. Complications may have already occurred or the operator may have noted other factors periprocedurally that put the patient at increased risk. The timing of the procedure may have influenced the decision to observe overnight; for example, late cases may have stayed overnight as a convenience factor. These data were unfortunately not available for analysis. However, a large majority of patients were admitted and did not have complications, suggesting we are perhaps overly cautious with who we monitor. Our study consisted of a low number of transradial cases, which are becoming more widely adopted. We would expect, however, that the addition of more transradial cases would be associated with an even lower event rate, especially those related to vascular injury. Ultimately, an adequately powered multicenter randomized trial is needed to truly have same-day discharge become the standard of care.

Conclusion

Our study is the largest to date looking at patient outcomes across a range of ACEF levels. Our results show that same-day PCI is safe and can even be extended to a higher-risk population.

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