Where Does Your Cath Lab Stand? A Contemporary View of Cath Labs, 2012.

Dr. Gregory Dehmer and colleagues, from the American College of Cardiology (ACC) National Cardiovascular Data Registry and the CathPCI Registry, published a report in November 2012 entitled, “The Contemporary View of Diagnostic Catheterization and PCI in the United States,” with data collected from 2010 to June 2011.¹ This remarkable report provides us with informative and helpful data, and insights to aid our understanding of the current status of cardiac cath labs in this country, along with where each of our individual labs might sit. I thought a review of this particular paper would be particularly enlightening.

The CathPCI Registry

The CathPCI registry, part of the National Cardiovascular Data Registry (NCDR), collects data from approximately 85% of cardiac catheterizations across the country. The data in the report by Dehmer et al¹ summarizes much of the information collected from January 1, 2010 to June 30, 2011. From the 1,110,150 patients undergoing diagnostic catheterization and 941,248 patients undergoing percutaneous coronary intervention (PCI), we learn a great deal about who cardiac catheterization patients are, and where, and why patients are having a cardiac catheterization. The results identified the number of labs contributing data over the many years of the Registry, the number of PCIs done in centers with and without surgery on-site, the percent of cases done at low-volume labs, the demographics, and clinical characteristics and presentations of patients undergoing cath and PCI in the United States. In addition, Dehmer et al report on the indications and use of stress testing and calcium scores from computed tomography angiography (CTA) leading to cath and PCI, and other important findings about how PCI is practiced and what complication rates are reported.

For example, the number of facilities participating in the registry has steadily increased from its inception in 1998 to 2011, with approximately 1400 facilities across the country now contributing. The number of records provided for study likewise increased over this time period to well over 13 million records, including both PCI at 4.2 million and diagnostic catheterization at 8.1 million. The current version of the data record had 253 data fields with definitions and specifications available online (see the NCDR website for more details at www.ncdr.com).  

The question of who pays for the cath and PCI procedure cannot be determined with certainty from this data, but the distribution of insurance payers according to patients undergoing PCI or diagnostic-only catheterizations indicated that private insurers covered 64% and 63% of patients, Medicare 51% and 49% of patients, and Medicaid 9.9% and 11% of patients.

PCI, on-site surgery and low-volume labs

On-site cardiac surgery was not available in 83% of low-volume cath labs (defined as those performing <200 PCIs annually). Low-volume labs represented 33% of the reporting facilities, but performed only 12% of the PCIs in the Registry report. Of labs performing between 11-200 PCIs per year, approximately 80% did not have on-site surgery (57 of 290 labs). For labs performing 201-400 PCIs per year, 30% of labs did not have on-site surgery. There were 24 labs that did more than 2000 PCIs annually and all but two had on-site surgery.

Cath and PCI patient characteristics and presentations

Patients older than 65 years old represented 39% of PCI procedures, with 12% being octogenarians undergoing PCI. Obesity was a common finding, with 80% of PCI patients having a body mass index (BMI) greater than 25 kg/m². The distribution of patients undergoing PCI by BMI told us that the median BMI was 29 kg/m2, with 80% of patients having BMI greater than 25 kg/m², 43% of patients greater than 30 kg/m2, and thin patients (BMI <19 kg/m² ) were <1% of the groups. Similar distributions were noted in the diagnostic catheterization population. 

Coronary artery disease risk factors, as one might expect, were also very common. Eighty percent had dyslipidemia, 80% had hypertension, 36% had diabetes, 28% were current or recent smokers, 13% had peripheral arterial disease, and 12% had cerebrovascular disease. Men underwent diagnostic catheterization slightly more often than women (56 vs. 44%), but were undergoing PCI much more often compared to women (67 vs. 33%).  

For PCI, 30% of patients had an old myocardial infarction (MI) (>7 days) and for diagnostic cath only, the number was 20%. For PCI and diagnostic cath procedures, 40% and 25% of patients had a prior PCI. PCI was performed in 34% of patients who had previous PCI <1 year prior to their procedure. Bypass surgery was noted in 19% of PCI patients and in 14% of the diagnostic-only patients. Patients on dialysis were uncommon and occurred in similar percentages (2.3% and 2.5%) for both PCI and diagnostic groups.

Clinical presentation of patients in the CathPCI Registry demonstrated some important differences between PCI and diagnostic catheterizations that could be expected, but until this report, were only speculation. 

• Asymptomatic patients (i.e. those with no angina or angina-equivalent symptoms) were present in 9% of the PCI group and 18% of the diagnostic-only group. 
• Atypical symptoms were present in 3% of the PCI group and 18% of the diagnostic-only group. 
• Of course, ST-elevation MI (STEMI) patients, on the other hand, were present in 16% of the PCI group and 2% of the diagnostic cath group; non-STEMI present in 18% of the PCI group and 9% of the diagnostic cath group, and unstable angina was present in 37% of the PCI and 33% of the diagnostic-only groups. 
• Stable angina presentation occurred in 18% of the PCI group and 21% of diagnostic cath group.  

Cath and PCI indications, and stress testing

The indications for PCI provided in this review offer some perspective on why we do catheterization in the first place. One-third of patients had stable angina (32%), staged PCI (6.4%), primary PCI (14%), STEMI or unstable angina (45%), and miscellaneous indications (2.5%). Other STEMI indications included late-arriving unstable angina, or stabilized MI after fibrinolytics and rescue PCI.  

Vessels treated during PCI are also reported. The highest treated vessel was the left anterior descending coronary artery (LAD) at 37%. In descending order after the LAD was the right coronary artery (RCA) at 35%, circumflex at 24%, saphenous vein graft at 6%, left main at 2%, ramus at 2%, and the internal mammary was 0.3% of all PCI. Single-vessel disease was treated in 86%, two vessels in 13%, and three vessels in 0.7%.

Use of IVUS, FFR and stress testing

Of special notice is the use of intravascular ultrasound (IVUS) and fractional flow reserve (FFR) in the PCI patients. Approximately 13% of all stenoses treated by PCI were “intermediate” severity (40-70%). Importantly, only 25% were evaluated further by IVUS (18%) or by FFR (only 7%). In these same patients, 8% had no symptoms or a normal stress test, with 23% of these lesions going on to further evaluation. Unfortunately, we do not know if these patients had acute coronary syndromes, where use of FFR is not indicated (in the first 24-48 hours) or if they had other evidence of ischemia, making intravascular diagnostics unnecessary. 

Stress testing indications for PCI patients was lower than for diagnostic-only patients (34% vs. 46%).   Calcium scores and computed CTA were used rarely, at less than 3% for diagnostic or PCI procedures. If a stress test was performed, an abnormal positive result occurred in 82% of PCI patients. However, the abnormalities were broken down into low, intermediate, and high risk features, occurring in 20%, 50%, and 30% of the studies. In the diagnostic-only group, 46% of patients had a stress test or imaging performed, and if an abnormal test was present (in 78%), the breakdown to low, intermediate, and high risk results  was different than that of PCI patients (32%, 50%, and 19%) with about half of the high-risk results compared to the PCI population. 

Standard (ECG) stress tests were performed in about 8% and 9% of both PCI and diagnostic patients, stress echo in 11% in both groups, and stress perfusion imaging in 82% of both groups. Of interest, no disease was present in the PCI population at 2.5% and 8.6% in diagnostic-only studies.

Procedural techniques:  

vascular access and closure

The procedural details reported also told us that the majority of patients were having femoral access at 91-93%, brachial access at 0.4%, and radial access at 7% and 8%, between PCI and diagnostic studies. As expected, mean fluoro time in the PCI group was 15 +/- 12 minutes. In the diagnostic only group, it was 5 +/- 6 minutes. In patients with bypass surgery and PCI of more than one vessel, the mean fluoro time was 20 minutes. In patients with bypass surgery, diagnostic fluoro time was 8 minutes. Contrast volume for PCI studies was about 197 +/- 90 mL, and 103 +/- 49 mL for diagnostic catheterizations only. Increases in contrast for multivessel PCI in patients with coronary artery bypass graft surgery (CABG) were about 20% over the mean volume of contrast.

Primary PCI was performed for STEMI with a median door-to-balloon time of 65 minutes for non-transfer patients and 121 minutes for transfer patients. The in-hospital adjusted mortality in STEMI patients was 5.2%. 

Current hemostasis techniques used in procedures came as a surprise to me. Comparing PCI with diagnostic-only procedures, results showed:

• Manual compression was used in 37% (PCI) versus 38% (diagnostic) of cases; 
• Sealants were used in 27% versus 29% of cases; 
• Mechanical compressors were used in 12% versus 10% of cases; 
• Suture closure was used in 8% versus 4% of cases;
• Patch closure was used in 7% versus 10% of cases; and
• Staple closure was used in less than 0.01% of cases.

Complications of cath and PCI: CABG and bleeding

Complications are updated in this manuscript, with the separation of complications between PCI and diagnostic cath (without STEMI patients). For diagnostic catheterization, any complication occurring is 1.35%, very low and consistent with historical numbers. For PCI, as expected, any complication rate is 4.53%. Death, cerebrovascular accident (CVA) and shock rates for diagnostic cath are 0.06%, 0.17% and 0.24%, and for PCI, rates are 0.62%, 0.17% (twice as many hemorrhagic strokes) and 0.47%.    

For diagnostic caths, CABG performed during admission was 7.5%, but emergency (0.27%) and urgent CABG rates (5%) likely reflected cases of severe disease and rarely, complication requiring surgical intervention. In the PCI groups without STEMI (787,980 patients), any adverse event was reported at 4.5%. CABG during admission of 0.81% was strikingly lower than that of diagnostic procedures. Bleeding complications differed between the PCI and diagnostic groups, with any bleeding event in 1.4% of the PCI group versus 0.49% in the diagnostic; this is consistent with the more intense anticoagulation used for PCI. Types of bleeding complications were also reported, and those having PCI with STEMI had the highest rates of all bleeding complications for any hematoma, hematoma greater than 5%, bleeding at access site, retroperitoneal bleeding, gastrointestinal (GI) bleeding, genitourinary (GU) bleeding, or other bleeding. Diagnostic-only cath without STEMI had bleeding rates of any hematoma at access site of 0.18%, bleeding at access site 0.1% and retroperitoneal bleeding of 0.04%, very low numbers.

PCI mortality

The unadjusted PCI mortality in our modern era demonstrates that salvage PCI (e.g. shock) had a mortality rate of 51.3%, emergency STEMI procedures a mortality rate of 4.7%, emergency procedures that are not STEMI a mortality rate of 5.8%, urgent procedures a mortality rate of 0.8% and elective procedures a mortality rate of 0.2%. These rates are lower than historical reports from the 1980s and 1990s.  

The value of the registry is in helping us understand the practice of invasive cardiology and direct our attention to areas requiring higher levels of quality input for the physician and hospital practices. The practice characteristics of invasive and interventional cardiology can be determined from review of these data, as well as our use of different devices. Why the rates of use are different requires more detail, and will serve to spur our curiosity and share practice experiences. I hope this review of U.S. current cath lab statistics will let you see where your lab matches up with the current national trends and if it is not aligned, stimulate you to ask why.

Reference

1. Dehmer GJ, Weaver D, Roe MT, et al. A contemporary view of diagnostic cardiac catheterization  and percutaneous coronary intervention in the United States. A report from the CathPCI Registry of the National Cardiovascular Data Registry, 2010 through June 2011. J Am Coll Cardiol. 2012;60:2017-2031.