The use of percutaneous aortic balloon balvotomy (PABV) in high surgical risk patients has resurged because of development of less invasive endovascular therapies. We compared outcomes of concomitant PABV and percutaneous coronary intervention (PCI) with PABV alone during same hospitalization using nation’s largest hospitalization database. We identified patients and determined time trends using the International Classification of Diseases, Ninth Revision, Clinical Modification, procedure code for valvulotomy from Nationwide Inpatient Sample database 1998 to 2010. Only patients >60 years with aortic stenosis were included. Primary outcome included in-hospital mortality, and secondary outcomes included procedural complications, length of stay (LOS), and cost of hospitalization. Total 2,127 PABV procedures were identified, with 247 in PABV + PCI group and 1,880 in the PABV group. Utilization rate of concomitant PABV + PCI during same hospitalization increased by 225% from 5.1% in 1998 to 1999 to 16.6% in 2009 to 2010 (p <0.001). Overall in-hospital mortality rate and complication rates in PABV + PCI group were similar to that of PABV group (10.3% vs 10.5% and 23.4% vs 24.7%, respectively). PABV + PCI group had similar LOS but higher hospitalization cost (median [interquartile range] $30,089 [$21,925 to $48,267] versus $18,421 [$11,482 to $32,215], p <0.001) in comparison with the PABV group. Unstable condition, occurrence of any complication, and weekend admission were the main predictors of increased LOS and cost of hospital admission. Concomitant PCI and PABV during the same hospitalization are not associated with change in in-hospital mortality, complications rate, or LOS compared with PABV alone; however, it increases the cost of hospitalization.
Coronary artery disease (CAD) and aortic stenosis (AS) share similar atherosclerosis risk factors and, therefore, coexist in up to 50% of the patients who present with symptomatic AS. The traditional management option of surgical aortic valve replacement with coronary artery bypass graft is not feasible in up to 60% of the patients with severe symptomatic AS because of high operative risk owing to their multiple co-morbidities. With the development of transcatheter aortic valve replacement (TAVR), studies have noted percutaneous aortic balloon balvotomy (PABV) as a bridge to valve replacement in up to 37% of the patients who were initially considered inoperable. Percutaneous management of CAD and AS with percutaneous coronary intervention (PCI) and PABV is now increasingly performed in these high-risk patients as a bridge to TAVR. Currently, there is paucity of data regarding feasibility and safety of combined PABV and PCI with previous studies being limited by small sample size. The aim of this study was to determine in-hospital outcomes of concomitant PABV plus PCI and compare them with PABV alone using the nation’s largest hospitalization database.
Methods
Data were obtained from the Nationwide Inpatient Sample (NIS), which is the largest available database of hospital inpatient stays in the United States. The 2010 NIS contains all discharge data from 1,051 hospitals located in 45 states, approximating a 20% stratified sample of US community hospitals. Data from the NIS have previously been used to identify, track, and analyze national trends in health care usage, patterns of major procedures, access, disparity of care, trends in hospitalizations, charges, quality, and outcomes. Each individual hospitalization is de-identified and maintained in the NIS as a unique entry with 1 primary discharge diagnosis and <24 secondary diagnoses during that hospitalization. Each entry also carries information on demographic details, insurance status, co-morbidities, primary and secondary procedures, hospitalization outcome, and length of stay (LOS) with safeguards to protect the privacy of individual patients, physicians, and hospitals. Annual data quality assessments are performed to assure the internal validity of the database. To maintain the external validity, database is compared with the following data sources: the American Hospital Association Annual Survey Database, the National Hospital Discharge Survey from the National Center for Health Statistics, and the MedPAR inpatient data from the Centers for Medicare and Medicaid Services.
We queried the Health Care Cost and Utilization Project’s NIS between 1998 and 2010 using the International Classification of Diseases, Ninth Revision, Clinical Modification ( ICD-9-CM ) procedure codes of 35.96 for percutaneous valvuloplasty, 36.06 for non–drug-eluting coronary artery stents, 36.07 for drug-eluting coronary artery stents, and 00.4× in any of the procedural fields. Only patients >60 years with AS (424.1, 395.0, 395.2, 396.2, and 746.3) were included. Patients with concomitant mitral, tricuspid, or pulmonary stenosis were excluded (394.0, 394.2, 396.0, 396.1, 396.8, 397.0, 397.1, 746.0, 746.1, 746.5, 424.2, and 424.3).
We defined severity of co-morbid conditions using Deyo modification of Charlson comorbidity index (CCI). This index contains 17 co-morbid conditions with differential weights. The score ranges from 0 to 33, with higher scores corresponding to greater burden of co-morbid diseases ( Supplementary Table 1 ).
Procedural complications were identified by Patient Safety Indicators (PSIs), version 4.4, March 2012, which have been established by the Agency for Healthcare Research and Quality to monitor preventable adverse events during hospitalization. These indicators are based on ICD-9-CM codes and Medicare severity Diagnosis-Related Groups, and each PSI has specific inclusion and exclusion criteria. Procedural complications not included in PSI were identified using ICD-9-CM codes ( Supplementary Table 2 ). To prevent classification of a pre-existing condition (e.g., stroke or heart block) as a complication, cases with the ICD-9-CM code for a complication listed as the principal diagnosis were excluded. Unstable patients were defined as those having a listed code for shock ( ICD-9-CM code 785.5) or ventilator dependence ( ICD-9-CM code V461). This methodology of identifying patients who underwent procedures, co-morbid conditions, and associated complications has previously been used in several studies.
Stata IC 11.0 (Stata-Corp, College Station, Texas) and SAS 9.2 (SAS Institute Inc, Cary, North Carolina) was used for analyses, which accounted for the complex survey design and clustering. All analyses were performed using hospital-level discharge weights provided by the NIS to minimize biases. Differences between categorical variables were tested using the chi-square test, and differences between continuous variables were tested using Student’s t test, continuous variables with Gaussian distributions, and Kruskal-Wallis rank-sum tests for continuous variables with non-Gaussian distributions. p-Value less than 0.05 was considered significant.
Hierarchical mixed-effects models were generated to identify the independent multivariate predictors of in-hospital mortality, postprocedural complications, LOS, and cost of hospitalization. Two-level hierarchical models (with patient-level factors nested within hospital-level factors) were created with the unique hospital identification number incorporated as random effects within the model. Hierarchical mixed-effects logistic regression models were used for categorical dependent variables like in-hospital mortality and postprocedural complications, and hierarchical mixed-effects linear regression models were used for continuous dependent variables like LOS. LOS and cost of care were not normally distributed in the population and were, therefore, converted into logarithmic scale.
Variables with >10% missing data (race and type of admission) were not included in the multivariate model. Because majority of the procedures were performed in urban hospitals, we did not include rural or urban location of hospital in the model. In all multivariate models, we included hospital-level variables, such as hospital region, teaching versus nonteaching hospital, admission over the weekend, and patient-level variables like age, gender, CCI, unstable patient, and primary payer (with Medicare or Medicaid considered as referent). All interactions were thoroughly tested. Collinearity was assessed using variance inflation factor.
Results
A total of 2,127 (weighted n = 10,641) PABV procedures were identified, of which 247 (weighted n = 1,230) were PABV + PCI (PABV + PCI group) and 1,880 (weighted n = 9,411) were PABVs alone (PABV group). Table 1 demonstrates the baseline characteristics of the study population; 69% of the patients were >80 years in both groups. At baseline, the patients in the PABV + PCI group were noted to have significantly higher incidence of hypertension, diabetes, peripheral vascular disease, anemia, or coagulopathy compared with the PABV group. The PABV + PCI group also had significantly more emergent admissions and patients with CCI ≥2. Hemodynamic support with devices, such as intra-aortic balloon pump, Impella or TandemHeart, was used in 95 procedures: 32 (12.7%) in the PABV + PCI group and 63 (3.3%) in the PABV group. The utilization rate of concomitant PABV + PCI during the same hospitalization increased by 225% from 5.1% of PABVs in 1998 to 1999 to 16.6% of PABVs in 2009 to 2010 in the United States (p <0.001) ( Figure 1 ).
| PABV Only | PABV + PCI | P-Value | |
|---|---|---|---|
| Demographic variable | |||
| Total no. of procedures (Unweighted no.) | 1880 | 247 | |
| Total no. of procedures (Weighted no) | 9411 | 1230 | |
| Patient level variables | |||
| Age (years) | 0.9 | ||
| Median | 83 (78-88) | 84 (78-88) | |
| 65-79 | 28.9% | 26.4% | |
| ≥80 | 68.6% | 69.4% | |
| Gender | <0.001 | ||
| Male | 45.5% | 50.8% | |
| Female | 54.5% | 49.2% | |
| Race ∗ | 0.5 | ||
| White | 66.9% | 65.9% | |
| Non-white | 8.1% | 9.1% | |
| Missing | 25.0% | 25.0% | |
| Co-morbidities † | |||
| Charlson/Deyo co-morbidity index ‡ | <0.001 | ||
| 0 | 12.3% | 7.4% | |
| 1 | 28.5% | 22.0% | |
| ≥2 | 59.2% | 70.6% | |
| Obesity § | 4.0% | 3.6% | 0.1 |
| History of hypertension | 44.2% | 53.5% | 0.02 |
| History of diabetes | 20.8% | 31.5% | <0.001 |
| History of congestive heart failure | 6.6% | 2.8% | <0.001 |
| History of chronic pulmonary disease | 20.7% | 23.1% | 0.7 |
| Peripheral vascular disease | 11.1% | 20.1% | <0.001 |
| Renal failure | 29.3% | 35.4% | 0.1 |
| Neurological disorder or paralysis | 3.7% | 1.5% | <0.001 |
| Anemia or coagulopathy | 18.2% | 25.8% | <0.001 |
| Hematological or oncological malignancy | 6.4% | 3.9% | <0.001 |
| Weight loss | 3.0% | 2.9% | 0.4 |
| Rheumatoid arthritis or other collagen vascular Disease | 2.0% | 3.4% | 0.02 |
| Admission types | <0.001 | ||
| Emergent/Urgent | 53.9% | 55.9% | |
| Elective admission | 35.0% | 25.1% | |
| Unstable Patient ¶ | 7% | 12.4% | 0.003 |
| Admission day | 0.03 | ||
| Weekdays | 88.7% | 86.6% | |
| Weekend | 11.3% | 13.4% | |
| Length of stay [Median (interquartile range)] | 5 (2-12) | 7 (3-14) | 0.06 |
| Mortality, cost and outcome | |||
| Total charges ($)[Median (interquartile range)] | 18,421 (11,482-32,215) | 30,089 (21,925-48,267) | <0.01 |
| Disposition | 0.003 | ||
| Home | 63.3% | 59.7% | |
| Facility/others | 26.1% | 30.1% | |
| Death | 10.5% | 10.3% | 0.8 |
∗ Race was missing in 25% of the study population and hence excluded in the multivariable analysis.
† Variables are AHRQ co-morbidity measures, which were only available from 2002 through 2010.
‡ Charlson/Deyo co-morbidity index was calculated as per Deyo classification.
§ Obesity was defined as (Body Mass Index >30).
¶ Unstable was defined as (DX1-DX25) having a listed code for shock (ICD-9-CM code 785.5) or ventilator dependence (ICD-9-CM code V461).
Overall in-hospital mortality rate in the PABV + PCI group was not statistically different from that of the PABV group (10.3% vs 10.5%). The significant predictors of in-hospital mortality in the PABV + PCI group were increasing co-morbidities (odds ratio [OR] 1.17; 95% confidence interval [CI] 1.01 to 1.35, p = 0.03), unstable patient (OR 6.19; 95% CI 3.45 to 11.09, p <0.001), occurrence of any complication (OR 2.81; 95% CI 1.85 to 4.28, p <0.001), and admission over the weekend (OR 2.12; 95% CI 1.23 to 3.67, p = 0.007; Supplementary Table 3 ).
The overall complications rates were also similar in PABV + PCI group versus PABV group (23.4% vs 24.7%, p = 0.80). Figure 2 demonstrates the comparison of various complications in the 2 groups. Most common complications in the PABV + PCI group were postprocedure respiratory failure (8.3%), vascular (7.5%), and cardiac (6.7%). Unstable patients were a significant predictor of higher complications (OR 5.09; 95% CI 2.97 to 8.70, p <0.001; Supplementary Table 3 ).
Overall, there were no significant differences in clinically relevant end points when PABV + PCI group was compared with the PABV group ( Tables 2 and 3 ). However, patients in the PABV + PCI group had significantly increased cost of hospitalization (median [interquartile range] $30,089 [$21,925 to $48,267] versus $18,421 [$11,482 to $32,215], p <0.001) compared with those of the PABV group ( Table 3 ). The significant predictors of increased LOS and cost of hospital admission were unstable condition, occurrence of any complication, weekend admission, and increasing co-morbidities ( Table 4 ).
| Complications | PABV + PCI | PABV only | P Value |
|---|---|---|---|
| Mortality | 10.3% | 10.5% | 0.9 |
| Any complications | 23.4% | 24.7% | 0.8 |
| Mortality + any complications | 28.7% | 29.5% | 0.9 |
| Death + Vascular + Stroke + Cardiac + Requirement of Open heart surgery | 24.1% | 24.3% | 0.1 |
| Vascular complications | 7.5% | 6.7% | 0.6 |
| 1) Postop-hemorrhage requiring transfusion † | 2.5% | 2.8% | 0.8 |
| 2) Vascular injury | 5.1% | 4.3% | 0.5 |
| Cardiac complications | 6.7% | 7.4% | 0.8 |
| 1) Iatrogenic cardiac complications including periprocedural myocardial infarction | 4.6% | 4.5% | 0.8 |
| 2) Pericardial complications | 0.4% | 0.8% | 0.5 |
| 3) Complete Heart Block | 1.6% | 3.2% | 0.2 |
| Requiring CABG | 1.5% | 2.5% | 0.4 |
| Respiratory complications | 8.3% | 7.6% | 0.6 |
| Postop – Stroke/TIA/Stroke effects | 1.7% | 3.2% | 0.2 |
| Renal and metabolic complications | 0.8% | 1.9% | 0.2 |
| 1) Acute renal failure requiring dialysis | 0.8% | 1.8% | 0.2 |
| 2) Acute severe metabolic derangement | 0% | 0.1% | 0.7 |
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