Characteristics of Patients Undergoing Cardiac Catheterization Before Noncardiac Surgery: A Report From the National Cardiovascular Data Registry CathPCI Registry

Importance  Many patients undergo cardiac catheterization and/or percutaneous coronary intervention (PCI) before noncardiac surgery even though these procedures are not routinely indicated. Data on this cohort of patients are limited.

Objective  To describe the characteristics, angiographic findings, and treatment patterns of clinically stable patients undergoing cardiac catheterization and/or PCI before noncardiac surgery in a large national registry.

Design, Setting, and Participants  This study is a retrospective, descriptive analysis of National Cardiac Data Registry CathPCI Registry diagnostic catheterization and PCI data from July 1, 2009, through December 31, 2014. Data analysis was performed from April 21, 2015, to January 4, 2016. The study included 194 444 patients from 1046 sites who underwent coronary angiography before noncardiac surgery. Patients with acute coronary syndrome, cardiogenic shock, cardiac arrest, or emergency catheterization were excluded.

Main Outcomes and Measures  Demographic characteristics, preprocedure noninvasive testing results, angiographic findings, and treatment recommendations are summarized. Among the 27 838 patients who underwent PCI, procedural details, inpatient outcomes, and discharge medications are reported.

Results  Of the 194 444 included patients, 113 590 (58.4%) were male, the median age was 65 years (interquartile range, 57-73 years), and 162 532 (83.6%) were white. Most were overweight or obese (152 849 [78.6%]), and 78 847 (40.6%) had diabetes mellitus. Most patients were asymptomatic (117 821 [60.6%]), although 112 302 (57.8%) had been taking antianginal medications within 2 weeks of the procedure. Prior noninvasive stress testing was reported in 126 766 (65.2%), and results were positive in 109 458 (86.3%) of those with stress data. Obstructive disease was present in 93 447 (48.1%). After diagnostic angiography, revascularization with PCI or bypass surgery was recommended in 46 380 patients (23.8%) in the overall cohort, 27 191 asymptomatic patients (23.1%), and 45 083 patients with obstructive disease (48.3%). In the 27 191 patients undergoing PCI, 367 treated lesions (1.3%) were in the left main artery and 3831 (13.8%) in the proximal left anterior descending artery. A total of 11 366 patients (40.8%) received drug-eluting stents. Complications occurred in a few patients, with a catheterization-related mortality rate of 0.05%.

Conclusions and Relevance  In the largest contemporary US cohort reported to date, most patients undergoing diagnostic catheterization before noncardiac surgery are asymptomatic. The discovery of obstructive coronary artery disease is common, and although randomized clinical trials have found no benefit in outcomes, revascularization is recommended in nearly half of these patients. The overall findings highlight management patterns in this population and the need for greater evidence-based guidelines and practices.

Although routine cardiac catheterization before noncardiac surgery is rarely indicated,¹ many patients with abnormal noninvasive cardiac test results undergo elective diagnostic catheterization as part of a preoperative evaluation. For example, nearly 55 000 patients from the National Cardiovascular Data Registry (NCDR) CathPCI Registry underwent preoperative diagnostic catheterizations before noncardiac surgery in 2010 to 2011.² Although this cohort represents a small subset of overall catheterization procedures performed, to our knowledge, there is a paucity of data describing this important cohort of patients and their procedural findings.

The role of preoperative cardiac catheterization is especially complicated given randomized trial data that have demonstrated no benefit of preoperative coronary revascularization by percutaneous coronary intervention (PCI) or coronary artery bypass grafting (CABG) in most patients.³ Consequently, preoperative guidelines (http://content.onlinejacc.org/article.aspx?articleid=1893784) recommend revascularization before noncardiac surgery only in selected circumstances.¹ Furthermore, a decision to intervene with PCI needs to be weighed against the risk of deferring surgery (because of the need for prolonged antiplatelet therapy) and increased risk of adverse cardiac events if surgery is performed early after stent placement.⁴ Despite these issues, the practice of preoperative revascularization persists, with nearly 19 000 patients in the 2010-2011 CathPCI Registry having a PCI performed in this setting.² Data on these PCI procedures remain limited.

The aim of this study was to use the only national registry that captures catheterization and PCI data in clinically stable patients before noncardiac surgery to perform the largest descriptive analysis of this population from July 1, 2009, through December 31, 2014. Our analysis had 2 major goals. First, we aimed to report the noninvasive testing, angiographic results, and treatment recommendations in patients undergoing any diagnostic catheterization before noncardiac surgery. Second, in patients undergoing PCI, we aimed to describe procedural decisions, discharge medications, and in-hospital outcomes.

The NCDR CathPCI Registry, cosponsored by the American College of Cardiology and the Society for Cardiovascular Angiography and Interventions, is a large, contemporary national registry of patients undergoing diagnostic cardiac catheterizations and/or PCI that captures approximately 85% of PCI procedures performed at more than 1400 hospitals (approximately 92% of nonfederal hospitals performing PCI⁵). Details of the registry, data collection, and monitoring have been previously described.^2,6 This study used version 4.0 of the CathPCI Registry, which had complete data for July 1, 2009, through December 31, 2014, at the time of analysis. Data analysis was performed from April 21, 2015, to January 4, 2016.

The institutional review board of Duke University Medical Center in Durham, North Carolina, approved the study after determining that the study met the definition of research not requiring informed consent. All the data in the NCDR are deidentified.

We included all 269 972 patients from the registry who had a procedure performed as part of a site-reported preoperative evaluation before noncardiac surgery. We then excluded 60 230 patients undergoing catheterization with suspected acute coronary syndrome, those who had unstable angina symptoms, and patients undergoing catheterization as part of a cardiac transplant evaluation (Figure 1). To minimize reporting bias, we further excluded patients from 509 sites not reporting any diagnostic catheterizations or PCIs. The final cohort therefore included 194 444 patients from 1046 sites.

All demographic and procedural data were defined by the most recent CathPCI Registry data dictionary.⁷ Obstructive coronary artery disease (CAD) was reported in multiple ways: per vessel, number of vessels, and per patient. A vessel was defined as having obstructive disease if there was more than 50% luminal stenosis in the left main artery or more than 70% stenosis for all other arteries or grafts. Number of diseased vessels included only the native circulation (range, 0-3), with a left main stenosis considered equivalent to 2 obstructive vessels. Patients were defined as having obstructive CAD if they had at least 1 vessel with obstructive disease. Because the use or findings of functional intravascular testing (eg, fractional flow reserve) were not routinely collected for diagnostic catheterizations, these were not used in defining obstructive CAD.

For this descriptive analysis, we summarized patient characteristics and symptoms, procedural details, angiographic findings, treatment recommendations, intraprocedure and postprocedure events, and discharge information. Where appropriate, patients undergoing diagnostic catheterization were compared with those undergoing PCI. In these cases, categorical variables are presented as frequencies, and differences between the column groups were assessed using the χ² or Fisher exact test, depending on sample size. Continuous variables are presented as median (interquartile range) and were compared where appropriate with the Kruskal-Wallis test. All analyses were performed using SAS statistical software, version 9.4 (SAS Institute Inc).

The study cohort included 194 444 patients, of whom 27 838 (14.3%) also underwent PCI. Of the overall cohort, 113 590 (58.4%) were male, the median age was 65 years (interquartile range, 57-73 years), and 162 532 (83.6%) were white. Nearly half the patients (93 766 [48.2%]) were clinically obese. Compared with the patients undergoing only diagnostic catheterization, patients undergoing PCI were significantly older, more likely to be male, and of white race (Table 1). A few patients had a history of CAD events in the overall cohort, including prior myocardial infarction (34 422 [17.7%]), prior PCI (36 725 [18.9%]), or prior CABG (23 487 [12.1%]), and these events were more prevalent in patients undergoing PCI (P < .001 for all). Diabetes was present in 78 847 (40.6%) and was significantly increased in patients undergoing PCI (13 244 [47.6%] vs 65 603 [39.4%], P < .001). Other cardiac risk factors and high-risk comorbidities (eg, peripheral vascular disease) were not routinely recorded for patients undergoing diagnostic catheterization but were highly prevalent in the PCI cohort.

Before catheterization, 117 821 (60.6%) of the inclusion cohort was reported by site as clinically asymptomatic, 34 936 (18.0%) had atypical chest pain symptoms considered unlikely to be ischemic, and 41 687 (21.4%) had stable angina symptoms. The severity of angina was significantly increased in patients undergoing PCI compared with those undergoing diagnostic catheterization alone (eTable in the Supplement). Antianginal medication use within 2 weeks of catheterization was present in 112 302 (57.8%) of the overall cohort and was more common in the PCI cohort. In contrast, the presence of heart failure symptoms, symptom severity, and left ventricular dysfunction was more common in the cohort undergoing diagnostic catheterization alone (eTable in the Supplement).

Preoperative stress testing was performed in 126 766 (65.2%), not performed in 2484 (1.3%), and unknown in 65 194 (33.5%) of the overall cohort. Among patients who underwent preoperative stress tests, myocardial perfusion imaging (MPI) accounted for most tests performed (108 932 [85.9%]) followed by stress echocardiography (12 928 [10.2%]) (Table 2). Among patients with stress tests performed, 109 458 (86.4%) of the test results were positive, 9477 (7.5%) were negative, and 5205 (4.1%) were equivocal. The risk severity was available in 75 539 patients (71.4%) with positive MPI or stress echocardiography results; it was reported as low in 19 395 (25.7%), intermediate in 39 089 (51.7%), and high in 17 055 (22.6%). Patients undergoing PCI were more likely to have a positive stress test result compared with patients undergoing diagnostic catheterization alone (Table 2). Overall, patients with stable angina symptoms were more likely to have a positive stress test result (26 788 [88.8%]) compared with asymptomatic patients (65 233 [86.4%]) or those with atypical chest pain (17 437 [82.7%]) (P < .001 for comparison).

Most diagnostic procedures (166 060 [85.4%]) were performed on outpatients. Catheterization was classified by the operator as elective in 178 375 patients (91.7%) and urgent in 16 069 (8.3%). Obstructive disease was present in 93 447 (48.1%) of the overall cohort, 66 334 (39.8%) of those undergoing diagnostic catheterization only, and 27 113 (97.4%) of the PCI cohort. Left main disease (≥50% stenosis) was present in 11 753 (6.1%) of the overall cohort. Two or 3 vessel disease combined was present in 54 764 (28.2%) of the overall cohort and in 13 906 (50.0%) of the cohort undergoing PCI (Figure 2).

In the overall cohort, obstructive disease was present in 56 688 patients (48.1%) who were asymptomatic, 12 959 patients (37.1%) with atypical chest pain, and 23 800 (57.1%) with stable angina symptoms (P < .001). Of those with data available for analysis, prior stress test results were positive in 59 411 patients (90.4%) with obstructive disease and in 49 760 (82.0%) with nonobstructive disease. Obese patients (body mass index [calculated as weight in kilograms divided by height in meters squared] ≥30) were significantly more likely than nonobese patients to have a false-positive stress test result with no obstructive CAD by diagnostic angiography (30 092 [84.7%] vs 19 587 [78.1%], P < .001).

After diagnostic catheterization, conservative treatment was recommended in 134 723 patients (69.3%) in the overall cohort (23 756 [12.2%] receiving no treatment and 110 967 [57.1%] receiving medical therapy), PCI in 30 390 (15.6%), CABG (including hybrid approaches) in 15 990 (8.2%), and other cardiac therapy in 13 212 (6.8%). Revascularization (with PCI or CABG) was recommended in 27 191 asymptomatic patients (23.1%), 5602 patients (16.0%) with atypical chest pain, and 13 587 patients (32.6%) with stable angina symptoms (P < .001). Revascularization procedures were recommended in nearly half of patients with obstructive disease and rarely in patients with nonobstructive disease (45 083 [48.3%] vs 1249 [1.3%], P < .001). Among patients with positive stress test results and reported risk severity, revascularization was more frequently recommended in those with increased risk severity (eFigure in the Supplement). Treatment recommendations varied considerably by angiographic findings (Table 3).

Among the 27 838 patients who underwent PCI, the procedure was classified by the operator as elective in 23 798 (85.5%), urgent in 3980 (14.3%), and emergency in 46 (0.2%). A total of 1267 PCI procedures (4.6%) were classified as staged (planned PCI based on prior catheterization findings). Femoral access was most common (23 198 [83.3%]) followed by radial access (4422 [15.9%]). The use of mechanical support was rare (122 [0.4%]) as were adjunctive therapies, such as intravascular ultrasonography (656 [2.3%]) or fractional flow reserve (972 [3.5%]).

Drug-eluting stents were used in 11 366 patients (40.8%), bare metal stents in 13 576 patients (48.8%), and no stent in 2896 patients (10.4%) undergoing PCI. Most patients had 1 (20 382 [73.2%]) or 2 (5960 [21.4%]) lesions treated during the procedure. A few lesions were at the site of a former stent (2237 [8.5%]) or within a bypass graft (1357 [4.9%]). Overall, 367 (1.3%) of the treated lesions were located in the left main artery, and 3831 (13.8%) were in the proximal left anterior descending artery. Site-reported procedural success was achieved in 26 070 patients (93.7%).

Complications related to PCI occurred in a few patients. Coronary artery dissection occurred in 355 (1.3%), periprocedural myocardial infarction in 466 (1.7%), vascular complications in 121 (0.4%), stroke in 38 (0.1%), and renal failure in 31 (0.1%). Fourteen patients (0.05%) died the same day as the procedure, and 8 deaths occurred in the catheterization laboratory. Bleeding events within 72 hours occurred in 371 patients (1.3%), with most occurring at the access site.

Among the patients undergoing PCI, 27 738 (99.6%) were discharged alive, with cardiac or valvular causes being the most common cause of death. Coronary artery bypass grafting was performed during the hospitalization in 158 patients (0.6%). The most common CABG indication was PCI failure (71 operations [45.0%]) followed by PCI complication (46 operations [29.1%]). Additional major surgery was performed in 1019 patients (3.7%). Most patients were discharged to home (26 840 [96.8%]) after a mean postprocedure length of stay of 2 days.

After PCI, 26 272 patients (95.9%) were discharged with aspirin and 23 055 (85.2%) with a statin medication. Most patients (26 234 [95.2%]) were discharged with antiplatelet medications, with clopidogrel bisulfate (22 724 [82.7%]) and prasugrel (2585 [9.4%]) being the most common. β-Blockers were prescribed in 20 367 patients (75.3%) and angiotensin-converting enzyme inhibitors or angiotensin receptor blockers in 16 637 (61.6%).

In this large, contemporary US registry, we found that most clinically stable patients undergoing diagnostic catheterization before noncardiac surgery are asymptomatic. However, there is a high prevalence of cardiac risk factors and prior CAD, and most patients have had a positive stress test result. Obstructive CAD by angiography is common, and revascularization is recommended in nearly half of these patients. The subset of patients undergoing preoperative PCI had a higher disease burden, and bare metal stents were most commonly used. To our knowledge, this is the largest descriptive analysis of this selected but understudied population to date, and it highlights many dilemmas in diagnosing and managing CAD in the preoperative setting.

Current preoperative guidelines recommend a stepwise approach that incorporates clinical risk stratification and the selective use of noninvasive imaging to detect myocardial ischemia in patients with uncertain or limited exercise capacity.¹ If noninvasive test results are abnormal, cardiac catheterization and revascularization should be considered according to general revascularization guidelines.^8,9 Routine diagnostic cardiac catheterization (including the use of cardiac computed tomographic angiography) for risk stratification is not recommended.¹

Our findings reveal the consequences and downstream effects of applying the aforementioned algorithm to preoperative risk assessment. Although we cannot be certain, it is reasonable to surmise that the high rate of asymptomatic patients referred for catheterization reflects, at least in part, a high frequency of patients with poor or unknown exercise tolerance undergoing recommended pharmacologic stress testing. Poor exercise tolerance correlates with a higher burden of medical comorbidities,¹⁰ many of which are also risk factors for CAD.¹¹ The confluence of these risk factors increases the likelihood of a positive noninvasive stress test result¹² and subsequent referral to invasive angiography for definitive coronary assessment. Furthermore, the high prevalence of obesity may increase the rate of positive stress test results because this condition has been associated with a higher rate of artifact-related false-positive stress test results (a finding similarly observed in our cohort), unless corrective imaging techniques are used.^13-15 Our study indicates that the ensuing population referred for diagnostic catheterization therefore has a high prevalence of obstructive CAD and a high rate of false-positive stress test results.

Given these patient characteristics, it is plausible that many physicians refer patients directly to diagnostic catheterization, which may in part explain the lack of stress test data in one-third of our study sample. Relatedly, an alternative approach using preoperative cardiac computed tomographic angiography to noninvasively identify or exclude high-risk obstructive CAD appears attractive and has generated research.^16-18 However, the cost-effectiveness of this strategy has been questioned given the low prevalence of high-risk CAD in the studied populations.^16-18 It is also unclear whether the identification of obstructive CAD by cardiac computed tomographic angiography would avert or rather prompt referral to invasive angiography, as has been seen in other populations.^19,20

The dilemma in identifying obstructive CAD in the preoperative setting is that randomized clinical trials have not identified a benefit of subsequent revascularization. The Coronary Artery Revascularization Prophylaxis trial was the largest randomized clinical trial to address this question. In that trial of 510 patients scheduled for elective high-risk vascular operations, neither preoperative CABG nor PCI reduced postoperative myocardial infarction or mortality at 2.7 years.³ A post hoc analysis of patients with unprotected left main artery disease (who were screened but not randomized in the Coronary Artery Revascularization Prophylaxis trial) suggested potential benefit from revascularization in this limited subset.²¹ On the basis of the findings of this trial, guidelines do not recommend routine revascularization to reduce perioperative events.¹ Furthermore, preoperative PCI is advised only for left main artery disease in patients who are ineligible for CABG and those with acute coronary syndrome.¹

There are sparse contemporary registry data of preoperative angiography and/or PCI in patients with stable CAD. To our knowledge, the only previous study²² described 2592 preoperative PCI procedures performed during 7 years in a Michigan registry. Compared with patients undergoing elective PCI, preoperative patients had greater comorbidities and were more likely to receive bare metal stents. Left main artery disease was present in 3% of patients and 3-vessel disease in 19.1%, but specific anatomical information or diagnostic catheterization findings were not reported. In contrast, our study provides pre-PCI diagnostic catheterization findings, treatment recommendations, and PCI details in a much larger, nationally representative population. With regard to revascularization, most patients who were advised to undergo CABG did not have left main artery disease. Although our data cannot assess the appropriateness of PCIs performed, only 1% of those reported were for left main artery lesions.

Our findings emphasize an inherent conflict between diagnostic and revascularization guideline recommendations. Physicians performing the preoperative evaluation are encouraged to follow an algorithm that will discover obstructive CAD in many patients but to proceed with a revascularization strategy in only a few. Such restraint of the oculostenotic reflex may be difficult to achieve,²³ especially if referring physicians are unaware of the lack of evidence of benefit of routine revascularization on postoperative outcomes. A decision to proceed with revascularization could be furthered by the expectations of anesthesiologists and surgeons, some of whom may feel uneasy proceeding to an operation with unrevascularized CAD despite the lack of evidence of benefit. To mitigate this diagnostic-therapeutic cascade,²⁴ future revisions to the guidelines may need to reexamine the use of noninvasive imaging and reemphasize the primacy of clinical risk scores to guide management, a process that occurs well before the patient is in the catheterization laboratory.

Our findings draw attention to a further challenge in preoperative PCI: the choice of stent and subsequent dual antiplatelet therapy (DAPT). As expected, our study indicates that drug-eluting stents are used much less often in the preoperative setting than in elective PCI,² likely because the succeeding 12 months of DAPT can lead to an unacceptable deferral of surgery. Still, the placement of a bare metal stent will defer most operations for 4 to 6 weeks until DAPT can be safely discontinued.¹ Furthermore, there are observational data that suggest that the risk of increased adverse cardiac events persists up to 6 months regardless of stent type.⁴ Our study highlights the need for further outcomes data and prospective trials to guide these decisions.

Our findings have several limitations. First, we did not know the surgical procedures that prompted cardiac evaluation, their urgency, or their surgical risk. We also did not know the timing, performance, or outcome of surgery after the catheterization and/or PCI or conversely the occurrence or timing of any PCI after surgery. Some patients may have undergone catheterization and/or PCI before solid-organ transplant, in which preoperative cardiac guidelines differ slightly but not materially with regard to the routine use of these procedures.²⁵ Second, because reporting to the NCDR is voluntary, it is possible that some centers do not report all catheterizations performed, particularly diagnostic studies without PCI. However, NCDR data audits have demonstrated good quality for diagnostic angiograms reported.⁶ To further mitigate this potential bias, we focused on centers that routinely provide diagnostic and interventional catheterization data. Third, the NCDR does not capture complete data about the presence or timing of CABG procedures performed. Fourth, the presence or absence of preoperative stress testing was not reported in nearly a third of patients. However, there is little reason to suspect the missing data would substantially change the robust trends we observed. Finally, the recommended duration of post-PCI antiplatelet therapy is not collected by the CathPCI Registry, although there is little reason to postulate a wide deviation from standard DAPT recommendations.⁹

In what we believe to be the largest contemporary US registry, most patients referred for catheterization before noncardiac surgery are described as asymptomatic, but they are commonly found to have obstructive CAD. Although randomized clinical trials have not found a benefit, revascularization is recommended in nearly half of these patients. Treatment recommendations in those with obstructive CAD are split nearly evenly between medical or conservative therapy and revascularization. These data highlight the dilemmas of management in this population and the need for better evidence-based guidelines and practices.

Accepted for Publication: January 9, 2016.

Corresponding Author: Rajesh V. Swaminathan, MD, Greenberg Division of Cardiology, Weill Cornell Medical College, 520 E 70th St, Starr 431, New York, NY 10021 (rvs9001@med.cornell.edu).

Published Online: March 28, 2016. doi:10.1001/jamainternmed.2016.0259.

Author Contributions: Drs Schulman-Marcus and Swaminathan had full access to all the data in the study and take responsibility for the integrity of the data and the accuracy of the data analysis.

Study concept and design: Schulman-Marcus, Feldman, Rao, Prasad, Kim, Wong, Mohsen, Swaminathan.

Acquisition, analysis, or interpretation of data: Schulman-Marcus, Feldman, Prasad, McCoy, Garratt, Minutello, Vora, Singh, Wojdyla, Mohsen, Bergman, Swaminathan.

Drafting of the manuscript: Schulman-Marcus, Feldman, Mohsen, Swaminathan.

Critical revision of the manuscript for important intellectual content: All authors.

Statistical analysis: Schulman-Marcus, McCoy, Minutello, Vora, Wojdyla.

Administrative, technical, or material support: Feldman, Kim, Wong, Mohsen, Bergman.

Study supervision: Schulman-Marcus, Feldman, Rao, Prasad, Singh, Mohsen, Swaminathan.

Conflict of Interest Disclosures: Dr Feldman reported consulting for and/or receiving speaker’s fees from Eli Lilly and Company, Daiichi-Sankyo, Bristol-Myers Squibb, Pfizer, and Abbott Vascular. No other disclosures were reported.

Funding/Support: This research was supported by the National Cardiovascular Data Registry (NCDR).

Role of the Funder/Sponsor: The manuscript was reviewed by the NCDR for compliance with registry description and representation but the sponsor had no role in the design and conduct of the study, analysis and interpretation of the data, preparation of the manuscript, or decision to submit the manuscript for publication.

Disclaimer: The views expressed in this article represent those of the authors and do not necessarily represent the official views of the NCDR or its associated professional societies (http://cvquality.acc.org/NCDR).