The rate of concurrent right-heart catheterization (RHC) in patients undergoing left-heart catheterization (LHC) for coronary artery disease (CAD) indications or bilateral heart catheterization (BHC) is recommended as a measure of hospital quality, with higher rates suggesting over utilization. Our aim was to describe the prevalence of BHC and abnormal RHC findings in patients undergoing BHC with a primary indication for LHC. A retrospective analysis was performed for patients undergoing cardiac catheterization for CAD indications using the Department of Veterans Affairs Clinical Assessment Reporting and Tracking Program. Patients undergoing catheterization from October 2007 to September 2011 in 76 Veterans Affairs hospitals were included. Among 95,656 patients undergoing catheterization for CAD, 6,611 (6.9%) underwent BHC and 88,929 (93.0%) LHC. Among the patients undergoing BHC, 61.3% had at least 1 of the following abnormal RHC values: mean pulmonary artery (PA) pressure >25 mm Hg, pulmonary capillary wedge pressure (PCWP) >15 mm Hg, or pulmonary vascular resistance (PVR) >3 Woods units. A total of 37.5% of patients had mean PA pressures of 26 to 40 mm Hg and 11.1% had mean PA pressures >40 mm Hg. A total of 34.4% of patients had mean PCWP of 16 to 25 mm Hg and 13.6% had mean PAWP >25 mm Hg. A total of 16.5% of patients had PVR between 3 and 6 WU and 2.9% had PVR >6 WU. A total of 4.3% of patients met formal criteria for pulmonary arterial hypertension (defined as the combination of PA mean >25 mm Hg, PCWP ≤15 mm Hg, and PVR >3). In conclusion, these findings suggest that most BHC were performed for appropriate clinical reasons. Future studies should further explore BHC rate as an effective quality indicator.
Highlights
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A total of 6.9% of patients undergoing cardiac catheterization for coronary artery disease indications had bilateral heart catheterization (BHC).
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A total of 61.3% who did get a BHC had at least 1 significantly abnormal right-heart catheterization finding.
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Physicians in this study are appropriately selecting patients for BHC.
There are no reported established standards for bilateral heart catheterization (BHC) rates. Furthermore, rates may be affected by reimbursement pressures (both positive and negative), academic interest in teaching institutions, and administrative pressures to achieve a low BHC rate (perceived to be associated with better hospital quality). We hypothesize that rates of BHC in the Veterans Affairs (VA) health system, where providers are salaried and thus shielded from procedural reimbursement incentives, will provide insight into reasonable BHC rates in clinical practice. The aims of this study were (1) to describe, in the VA health care system, the incidence of BHC in patients undergoing catheterization for coronary artery disease (CAD) and (2) to describe the associated indications, findings, and complications of catheterization in these patients. These data can assist providers, administrators, and policy makers in better understanding the usefulness of BHC as a measure of hospital quality.
Methods
Launched in 2005, the Department of Veterans Affairs Clinical Assessment Reporting and Tracking (CART) program is a national clinical quality initiative for all VA cardiac catheterization laboratories. A key feature of the CART program is a clinical software application, designed to collect standardized data on all coronary angiograms and percutaneous coronary interventions (PCI) performed in the VA nationwide. The software is embedded in the VA electronic health record and allows providers to enter patient and procedural information (preprocedure assessment, cardiac catheterization, and PCI) as part of routine clinical workflow.
The CART software was designed using standardized definitions which conform to the definitions and standards of the American College of Cardiology’s National Cardiovascular Data Registry and incorporates features such as pull-down menus and automated clinical report generation to ensure uniformity of data entry by different providers and in different cardiac catheterization labs. Quality checks of the data are periodically conducted for completeness and accuracy. CART data quality has been previously documented.
All patients who underwent heart catheterization procedures for CAD indications at all 76 VA hospitals that perform cardiac catheterizations from October 1, 2007, to September 30, 2011, were included. CAD-related indications included (1) chest pain; (2) ischemic heart disease; (3) acute coronary syndromes; and (4) positive functional study. The primary analysis excluded patients with appropriate right-heart catheterization (RHC) indications (cardiac tamponade, congenital heart disease, valvular heart disease, cardiac transplant, heart failure, and cardiomyopathy), consistent with Agency for Healthcare Research and Quality (AHRQ) methods.
Among our cohort, we examined clinical characteristics, findings, and complications in patients who underwent BHC, and isolated left-heart catheterization (LHC). RHC findings included: (1) pulmonary artery pressure (PA) mean ≤25, 26 to 40, and >40 mm Hg; (2) pulmonary capillary wedge pressure (PCWP) ≤15, 16 to 25, and >25 mm Hg; (3) pulmonary vascular resistance (PVR) ≤3, 3 to 6 WU, and >6 WU; and (4) right atrial mean pressure ≤10, 10 to 20, >20 mm Hg. In addition, left ventricular end-diastolic pressure (LVEDP) was categorized as ≤15, 16 to 25, and >25 mm Hg. Rates of pulmonary arterial hypertension (PAH) were measured and defined as the combination of PA mean >25 mm Hg, PCWP ≤15 mm Hg, and PVR >3 WU.
Descriptive statistics about the patient characteristics, procedural findings, and procedural complications were stratified and compared between BHC and LHC. Means and SD for continuous variables were calculated. For discrete variables, both frequency counts and percentages were determined. p values were generated using either the 1-way analysis of variance or chi-square tests as appropriate for the continuous and discrete variables.
Results
From October 1, 2007, to September 30, 2011, 95,656 patients underwent coronary catheterization for CAD. Of these, 6,611 (6.9%) underwent BHC, 88,929 (93.0%) underwent isolated LHC, and 116 (0.1%) underwent isolated RHC. The proportion of BHC as a percentage of all LHC (including BHC) procedures remained stable from 2007 to 2011 ranging from 6.5% to 7.2% over the study period ( Figure 1 ).
Table 1 lists the demographics and clinical characteristics of patients undergoing BHC and LHC. There were substantial differences between both groups. In particular, patients undergoing BHC, compared with patients undergoing LHC, were more likely to be in New York Heart Association (NYHA) class III (33.6% vs 12.4%) and IV (3.3% vs 1.1%) functional status and were more likely to be in congestive heart failure (44.1% vs 17.1%, p <0.001). Of those patients who underwent BHC, the majority (93.7%) had a femoral approach.
| Variable | LHC | BHC | p-value |
|---|---|---|---|
| (n=88929) | (n=6611) | ||
| Mean age (SD) (Years) | 63.9 ± 9.5 | 67.1 ± 9.7 | <0.001 |
| Obese | 39770 (44.8%) | 3112 (47.2%) | <0.001 |
| Overweight | 18276 (20.6%) | 1232 (18.7%) | <0.001 |
| Ever-smoked | 53506 (60.3%) | 3902 (59.2%) | 0.08 |
| Hypertension | 80732 (91%) | 6128 (93%) | <0.001 |
| Diabetes mellitus | 39916 (45%) | 3334 (50.6%) | <0.001 |
| Chronic obstructive pulmonary disease | 18990 (21.4%) | 2026 (30.7%) | <0.001 |
| Chronic renal failure | 8664 (9.8%) | 956 (14.5%) | <0.001 |
| Estimated glomerular filtration rate (ml/min) | 97.4 ± 35.4 | 89.9 ± 35.9 | <0.001 |
| Peripheral vascular disease | 17959 (20.2%) | 1597 (24.2%) | <0.001 |
| Prior coronary bypass | 20091 (22.6%) | 1744 (26.5%) | <0.001 |
| Prior myocardial infarction | 23891 (26.9%) | 1835 (27.8%) | 0.11 |
| Prior percutaneous coronary intervention | 29783 (33.6%) | 1737 (26.4%) | <0.001 |
| Prior heart failure | 17038 (19.2%) | 3169 (48.1%) | <0.001 |
| CHF Status at presentation | <0.001 | ||
| No | 19109 (80.9%) | 1047 (53.5%) | |
| Unknown | 477 (2%) | 46 (2.4%) | |
| Yes | 4032 (17.1%) | 864 (44.1%) | |
| New York Heart Association Class | <0.001 | ||
| I | 7122 (31.6%) | 237 (12.9%) | |
| II | 11143 (49.5%) | 836 (45.6%) | |
| III | 2797 (12.4%) | 615 (33.6%) | |
| IV | 250 (1.1%) | 61 (3.3%) | |
| UNKNOWN | 1213 (5.4%) | 84 (4.6%) | |
| Hemoglobin (SD) (g/dL) | 13.8 ± 1.7 | 13.3 ± 1.8 | <0.001 |
| Heart rate (SD) (beats per min) | 70.5 ± 13.8 | 73.2 ± 15.6 | <0.001 |
| Systolic blood pressure (SD) (mmHg) | 131.6 ± 19.4 | 129.2 ± 20.5 | <0.001 |
| Cardiogenic shock | 464 (0.5%) | 113 (1.7%) | <0.001 |
Table 2 lists the complications rates for both groups of patients. In general, complications were very uncommon, with any complication occurring in only 1.4% of patients. The most common complication was groin hematoma occurring 0.8% in those who underwent BHC compared with 0.4% in LHC procedures (p <0.001).
| Variable | LHC | BHC | p-value |
|---|---|---|---|
| (n=88929) | (n=6611) | ||
| Any complication | 566 (0.6%) | 94 (1.4%) | <0.001 |
| Groin Hematoma | 322 (0.4%) | 54 (0.8%) | <0.001 |
| Death | 8 (0%) | 3 (0%) | 0.04 |
| Stroke | 18 (0%) | 1 (0%) | 0.99 |
| Coronary bypass | 3 (0%) | 0 (0%) | 0.99 |
| Retroperitoneal Hematoma | 7 (0%) | 0 (0%) | 0.99 |
| New cardiac tamponade | 0 (0%) | 1 (0%) | 0.09 |
| Acute cardiogenic shock | 18 (0%) | 8 (0.1%) | <0.001 |
| Acute pulmonary edema | 16 (0%) | 7 (0.1%) | <0.001 |
| Dysrhythmia | 173 (0.2%) | 24 (0.4%) | 0.006 |
| Acute respiratory distress | 21 (0%) | 8 (0.1%) | <0.001 |
Table 3 lists the distribution of RHC findings, based on the previously defined categories, in patients who underwent BHC. The left ventricular end-diastolic pressure was higher in the BHC group compared with the LHC group (18.0 mm Hg vs 15.8 mm Hg, p <0.001, respectively). Compared with the LHC group, patients undergoing BHC were less likely to undergo PCI (5% vs 11.2%, p <0.001), but more likely to receive an intra-aortic balloon pump (1.6% vs 4.3%, p <0.001).
| Variable (SD) | LHC (N=88929) | BHC (N=6611) | p-value |
|---|---|---|---|
| Abnormal right heart catheterization (n) | – | 4328 (61.3%) | |
| Left ventricular end-diastolic pressure (mmHg) | 15.82 (7.9) | 18.0 ± 8.8 | <0.001 |
| Right atrial mean pressure (mmHg) | – | 9.4 ± 6.4 | |
| Right ventricular systolic pressure (mmHg) | – | 41.4 ± 14.5 | |
| Pulmonary artery systolic pressure (mmHg) | – | 41.0 ± 14.9 | |
| Pulmonary artery mean pressure (mmHg) | – | 27.0 ± 10.8 | |
| Pulmonary artery mean >40mmHg (n) | – | 668 (11.1%) | |
| Mean pulmonary capillary wedge pressure (mmHg) | – | 16.6 ± 8.4 | |
| Thermodilution cardiac output (L/min) | – | 5.3 ± 1.6 | |
| Fick cardiac output (L/min) | – | 5.2 ± 1.4 | |
| Thermodilution cardiac index (L/min) | – | 2.6 ± 1.0 | |
| Fick cardiac index (L/min) | – | 2.6 ± 0.7 | |
| Arterial saturation (%) | – | 94.1 ± 4.7 | |
| Mixed venous Saturation (%) | – | 65.09 (8.45) | |
| Systemic vascular resistance (dyne*sec/cm 5 ) | – | 1362.02 (482.33) | |
| Pulmonary vascular resistance (Woods units) | – | 2.21 (1.6) |
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