The “obesity paradox” that patients with high body mass index (BMI) have good prognoses remains controversial. This study aimed to assess the impact of BMI on clinical outcomes in patients who underwent transcatheter aortic valve implantation (TAVI). Data from the French national TAVI registry were collected for 3,072 patients who underwent TAVI from January 2010 to October 2011. The patients were categorized into 4 groups according to BMI (kg/m 2 ): underweight (<18.5 kg/m 2 ), normal weight (18.5 to 25 kg/m 2 ), overweight (25 to 30 kg/m 2 ), and obese (>30 kg/m 2 ). Thereafter, clinical outcomes were compared among the 4 groups. The BMI distribution was 3.1% (n = 95), 44.1% (n = 1,355), 34.2% (n = 1,050), and 18.6% (n = 572). Although the 4 groups greatly differed in baseline clinical background, they had similar procedural success rates (95.8%, 97.1%, 97.3%, and 95.6%, p = 0.23). Major vascular complication was significantly associated with the underweight patients after adjusting for the other potential confounders (odds ratio 2.33, 95% confidence interval 1.17 to 4.46, p = 0.016). The cumulative postoperative survival rates were increasing across the 4 groups at 30 days (83.2%, 88.9%, 91.6%, and 93.0%, p = 0.003) and 1 year (67.9%, 73.6%, 77.4%, and 80.3%, p = 0.006). In a multivariate Cox regression analysis, the overweight and obese patients were independently associated with superior cumulative survival rate at 1 year (hazard ratios 0.74 and 0.71, 95% confidence intervals 0.57 to 0.97 and 0.59 to 0.87, p = 0.050 and 0.029, respectively). In conclusion, major morbidity and 1-year mortality were less in overweight and obese patients than those classified as normal weight even in a TAVI cohort.
Transcatheter aortic valve implantation (TAVI) has emerged as an alternative to conventional surgical aortic valve replacement for high-risk patients with severe aortic stenosis. Patients eligible for TAVI mainly comprise populations with a mean age of >80 years. Thus, most patients in the TAVI cohort are characterized with multiple co-morbidities and old age compared with conventional catheter or surgical candidates. To date, there are no available data demonstrating the relation between body mass index (BMI) and clinical outcomes in very elderly patients who underwent surgery. Recent results of the FRench Aortic National CoreValve and Edwards 2 (FRANCE 2) registry have been reported under the establishment of the French Society of Cardiology and French Society of Thoracic and Cardiovascular Surgery. This study, a subanalysis of the FRANCE 2 registry, compared clinical outcomes according to differences in BMI categories and investigated whether the protective role of obesity existed in very elderly patients who underwent TAVI.
Methods
At the beginning of January 2010, a national TAVI coordination and monitoring program was established in France to analyze patient characteristics and clinical outcomes in 33 medical centers in France and 1 center in Monaco, with the capability of performing TAVI using 1 of the following surgical approaches: transfemoral, transapical, subclavian, or other techniques such as direct transaortic or carotid routes. Each multidisciplinary team performing the procedure consisted of an interventional cardiologist, cardiothoracic surgeon, cardiologist, echocardiographer, anesthetist, imaging specialist, and geriatrician. The multidisciplinary teams identified symptomatic patients requiring TAVI for severe aortic stenosis and who were at high risk and ineligible for surgical aortic valve replacement owing to co-morbidities. In all the centers, each team determined the eligibility for TAVI based on systematic clinical, angiographic, multislice computed tomographic, and echocardiographic assessments. In the FRANCE 2 registry, TAVI was performed in 3,195 patients in 34 hospitals from January 2010 to October 2011. However, BMI information could not be obtained from 123 patients (3.8%). Hence, the data for the remaining 3,072 patients were analyzed in this study. The patients were divided into 4 groups according to the World Health Organization BMI categories (kg/m 2 ): underweight (<18.5 kg/m 2 ), normal weight (18.5 to 25 kg/m 2 ), overweight (25 to 30 kg/m 2 ), and obese (>30 kg/m 2 ). All the patients gave written informed consent before the procedure and agreed to anonymous processing of their data. The registry was approved by the Institutional Review Board of the French Ministry of Health.
The TAVI procedures have been previously described in detail. The following commercially available valves were used: the balloon-expandable prosthesis known as the Edwards SAPIEN valve (Edwards Lifesciences, Irvine, California) and the self-expandable prosthesis known as the Medtronic CoreValve ReValving system (Medtronic, Minneapolis, Minnesota). Valve choice was made by the individual teams; 30 centers implanted both devices, and 4 centers used only the Edwards valve. The Edwards valve devices were mainly implanted using the transfemoral, transapical, or transaortic routes. The Medtronic CoreValve was implanted using the transfemoral, subclavian, or carotid routes.
Mortality was adjudicated by an independent clinical events committee at 30 days, 6 months, and 1 year of the study follow-up period. All the adverse events were assessed according to the Valve Academic Research Consortium classification. In particular, bleeding complications were categorized as life threatening, major, or minor. Stroke and vascular complications were also categorized as major or minor. Postprocedural aortic and mitral regurgitations were assessed by echocardiography. Data were recorded on a standardized electronic case report form and sent to a central database (Axonal, Nanterre, France) through the Internet.
All statistical analyses were performed using the SPSS software (version 19; SPSS Inc., Chicago, Illinois). Continuous variables are expressed as mean ± SD, depending on the variable distribution. Categorical data are expressed as percentages of the total. Comparisons among the 3 age groups were performed using the Pearson bivariate and chi-square tests for categorical covariates and 1-way analysis of variance for continuous covariates. The Kaplan-Meier method was used to estimate the cumulative mortality rates in the groups. The mortality rates in each group were compared using the log-rank test. A univariate logistic regression analysis was performed to obtain the odds ratio (OR) for procedural complications. Thereafter, a multivariate logistic regression analysis was performed using the variables with p <0.10 in the univariate analysis for examining their independent association with procedural complications. A univariate Cox regression analysis was performed to obtain hazard ratios (HRs) for cumulative mortality rates 30 days and 1 year after TAVI. The covariates selected for the Cox regression multivariate model were (1) baseline clinical and procedural characteristics with p <0.10 (age, gender, hypertension, dyslipidemia, diabetes, previous cardiac surgery, aortic regurgitation, mitral regurgitation, and valve type) and (2) variables with p <0.10 in the univariate analysis (previous myocardial infarction, chronic obstructive pulmonary disease, New York Heart Association classification, renal insufficiency, ejection fraction, and logistic European System for Cardiac Operative Risk Evaluation [EuroSCORE]). In the logistic and Cox regression analyses, each BMI group (i.e., the underweight, overweight, and obese patients) was compared with the normal-weight group as the reference category. All the statistical tests were 2-sided, and a p <0.05 was considered significant.
Results
Of the 3,072 patients with BMI data (mean age: 82.8 ± 7.2 years, BMI: 26.1 ± 5.0 kg/m 2 , and logistic EuroSCORE score: 22.0 ± 14.3), 3.1% were underweight (n = 95), 44.1% were normal-weight (n = 1,355), 34.2% were overweight (n = 1,050), and 18.6% were obese (n = 572). There were several significant differences in age, BMI, gender, diabetes, dyslipidemia, hypertension, coronary artery disease, and other baseline patient characteristics among the 4 groups ( Table 1 ). The procedural characteristics and outcomes are listed in Table 2 . The valve types and approach routes were not statistically significantly different among the groups. High procedural success was achieved in all the groups (95.8% vs 97.1% vs 97.3% vs 95.6%, p = 0.23). The durations of stay in the intensive care unit were similar in all the groups, whereas the length of hospital stay was increasing across the 4 groups. No significant differences were observed in the incidence of Valve Academic Research Consortium–defined myocardial infarction, stroke, and bleeding complications or other procedural complications, except for major vascular complication (11.6% vs 4.4% vs 4.8% vs 5.4%, p = 0.018), among the 4 groups. The risk of major vascular complication in each group compared with the normal weight as the reference is presented in Figure 1 . Major vascular complications significantly occurred in the patients who were underweight (OR 2.83, 95% confidence interval [CI] 1.43 to 5.58, p = 0.003) and were similar after the adjustment for other influential factors (OR 2.32, 95% CI 1.16 to 4.61, p = 0.017). The underweight patients were also associated with increased risk of life-threatening and major bleedings (OR 2.01, 95% CI 1.00 to 4.03, p = 0.049), although this result does not indicate an independent association but a statistical trend in a multivariate model (OR 1.97, 95% CI 0.98 to 3.98, p = 0.058).
| Variable | BMI (kg/m 2 ) | p | |||
|---|---|---|---|---|---|
| <18.5 (n = 95) | 18.5–25 (n = 1,355) | 25–30 (n = 1,050) | >30 (n = 572) | ||
| Baseline clinical characteristics | |||||
| Age (yrs) | 84.0 ± 9.2 | 83.9 ± 6.9 | 82.6 ± 7.0 | 80.6 ± 7.1 | <0.001 |
| BMI (kg/m 2 ) | 17.4 ± 1.0 | 22.5 ± 1.7 | 27.2 ± 1.3 | 33.8 ± 4.0 | <0.001 |
| Body surface area (m 2 ) | 1.44 ± 0.11 | 1.65 ± 0.16 | 1.81 ± 0.16 | 1.93 ± 0.18 | <0.001 |
| Women | 75/95 (78.9) | 700/1,355 (51.7) | 445/1,050 (42.4) | 288/572 (50.3) | <0.001 |
| Diabetes mellitus | 9/95 (9.5) | 247/1,341 (18.4) | 296/1,036 (28.6) | 232/567 (40.9) | <0.001 |
| Dyslipidemia | 27/95 (28.4) | 594/1,341 (44.3) | 525/1,036 (50.7) | 333/567 (58.7) | <0.001 |
| Hypertension | 54/95 (56.8) | 870/1,341 (87.1) | 754/1,036 (72.8) | 441/567 (77.8) | <0.001 |
| New York Heart Association (III or IV) | 72/95 (75.8) | 1,022/1,355 (75.4) | 787/1,050 (75.0) | 138/572 (75.9) | 0.98 |
| Coronary artery disease | 25/95 (26.3) | 642/1,341 (47.9) | 520/1,036 (50.2) | 280/567 (49.4) | <0.001 |
| Peripheral artery disease | 14/95 (14.7) | 265/1,341 (19.8) | 232/1,036 (22.4) | 123/567 (21.7) | 0.18 |
| Renal insufficiency ∗ | 6/95 (6.3) | 140/1,349 (10.4) | 123/1,045 (11.6) | 48/569 (8.4) | 0.10 |
| Hemodialysis | 3/95 (3.2) | 38/1,341 (2.8) | 30/1,036 (2.9) | 11/567 (1.9) | 0.67 |
| Previous myocardial infarction | 5/95 (5.3) | 197/1,341 (14.7) | 181/1,036 (17.5) | 108/567 (19.0) | 0.002 |
| Previous stroke | 9/95 (9.5) | 138/1,341 (10.3) | 103/1,036 (9.9) | 51/567 (9.0) | 0.86 |
| Previous cardiac surgery | 6/95 (6.3) | 224/1,353 (16.6) | 255/1,047 (21.5) | 134/570 (23.5) | <0.001 |
| Chronic pulmonary artery disease | 26/95 (27.4) | 314/1,341 (25.5) | 264/1,036 (25.5) | 175/567 (30.9) | 0.008 |
| Permanent pacemaker | 9/95 (9.6) | 181/1,346 (13.4) | 154/1,041 (14.8) | 88/565 (15.6) | 0.33 |
| Logistic EuroSCORE | 23.3 ± 13.4 | 23.0 ± 14.8 | 21.7 ± 14.1 | 20.0 ± 13.4 | 0.20 |
| Echocardiographic data | |||||
| Ejection fraction (%) | 54.3 ± 16.3 | 52.4 ± 14.5 | 53.2 ± 14.0 | 55.1 ± 12.8 | 0.002 |
| Ejection fraction ≥50% | 63/94 (67.0) | 837/1,331 (62.9) | 687/1,026 (67.0) | 418/561 (74.5) | |
| Ejection fraction 30%–49% | 24/94 (25.5) | 406/1,331 (30.5) | 282/1,026 (27.5) | 122/561 (21.7) | <0.001 |
| Ejection fraction <30% | 7/94 (7.4) | 88/1,331 (6.6) | 57/1,026 (5.6) | 21/561 (3.7) | |
| Aortic valve area (cm 2 ) | 0.58 ± 0.18 | 0.65 ± 0.18 | 0.69 ± 0.18 | 0.73 ± 0.18 | <0.001 |
| Corrected aortic valve area (cm 2 /m 2 ) | 0.42 ± 0.17 | 0.40 ± 0.15 | 0.42 ± 0.10 | 0.39 ± 0.17 | 0.79 |
| Mean gradient (mm Hg) | 52.2 ± 21.6 | 47.8 ± 17.0 | 48.2 ± 16.0 | 48.0 ± 15.6 | 0.1 |
| Aortic regurgitation grade ≥2 | 24/90 (26.7) | 259/1,272 (20.4) | 172/981 (17.5) | 75/534 (14.0) | 0.002 |
| Mitral regurgitation grade ≥2 | 29/89 (32.6) | 301/1,282 (23.5) | 222/992 (22.4) | 93/540 (17.2) | 0.002 |
| Pulmonary artery pressure (mm Hg) | 47.4 ± 12.7 | 45.5 ± 14.4 | 45.1 ± 13.9 | 46.2 ± 13.9 | 0.41 |
| Variable | BMI (kg/m 2 ) | p | |||
|---|---|---|---|---|---|
| <18.5 (n = 95) | 18.5–25 (n = 1,355) | 25–30 (n = 1,050) | >30 (n = 572) | ||
| Valve type | |||||
| Medtronic CoreValve | 25 (26.3) | 426 (31.4) | 360 (34.3) | 208 (36.4) | 0.070 |
| Edwards SAPIEN valve | 70 (73.7) | 929 (68.6) | 690 (65.7) | 364 (63.6) | |
| Approach site | |||||
| Transfemoral | 74 (77.9) | 997 (73.6) | 785 (74.8) | 434 (75.9) | 0.62 |
| Transapical | 18 (18.9) | 249 (18.4) | 186 (17.7) | 93 (16.3) | 0.72 |
| Subclavian | 25 (2.1) | 82 (6.1) | 60 (5.7) | 36 (6.3) | 0.66 |
| Other approaches | 1 (1.1) | 27 (2.0) | 19 (1.8) | 9 (1.6) | 0.87 |
| Postprocedural variables | |||||
| Procedural success | 91 (95.8) | 1,316 (97.1) | 1,022 (97.3) | 547 (95.6) | 0.23 |
| Stay in hospital (day) | 9.6 ± 5.1 | 9.8 ± 7.8 | 10.0 ± 7.5 | 10.9 ± 9.2 | 0.034 |
| Stay in intensive care unit (day) | 4.0 ± 3.5 | 3.8 ± 4.9 | 4.0 ± 4.6 | 4.0 ± 4.9 | 0.50 |
| VARC-defined complication | |||||
| Myocardial infarction | 1 (1.1) | 23 (1.7) | 8 (0.8) | 6 (1.0) | 0.21 |
| Major stroke | 1 (1.1) | 34 (2.5) | 27 (2.6) | 8 (1.4) | 0.34 |
| Minor stroke | 3 (3.2) | 21 (1.5) | 10 (1.0) | 5 (0.9) | 0.16 |
| Major vascular complication | 11 (11.6) | 60 (4.4) | 50 (4.8) | 31 (5.4) | 0.018 |
| Minor vascular complication | 6 (6.3) | 69 (5.1) | 44 (4.2) | 42 (7.3) | 0.053 |
| Life-threatening and major bleedings | 10 (10.5) | 75 (5.5) | 57 (5.4) | 30 (5.2) | 0.21 |
| Minor bleeding | 8 (8.4) | 103 (7.6) | 80 (7.6) | 41 (7.2) | 0.97 |
| Other procedural complication | |||||
| New pacemaker implantation ∗ | 12/86 (14.0) | 148/1,129 (13.1) | 140/887 (15.6) | 75/477 (15.7) | 0.35 |
| 2-Valve implantation | 2 (2.1) | 27 (2.0) | 27 (2.6) | 13 (2.3) | 0.82 |
| Need for hemodialysis | 2 (2.1) | 21 (1.5) | 22 (2.1) | 7 (1.2) | 0.56 |
| Postprocedural aortic regurgitation | 0.60 | ||||
| 0 | 25/74 (33.8) | 435/1,128 (38.6) | 367/897 (40.9) | 203/483 (42.0) | |
| 1 | 33/74 (44.6) | 513/1,128 (45.5) | 407/897 (45.4) | 215/483 (44.5) | |
| 2 | 15/74 (20.3) | 169/1,128 (15.0) | 118/897 (13.2) | 61/483 (12.6) | |
| 3 | 1/74 (1.4) | 11/1,128 (1.0) | 5/897 (0.6) | 4/483 (0.8) | |
| Postprocedural mitral regurgitation (grade) | 0.10 | ||||
| 0 | 21/68 (30.9) | 432/1,101 (39.2) | 359/871 (45.6) | 212/465 (45.6) | |
| 1 | 30/68 (44.1) | 491/1,101 (44.6) | 373/871 (42.6) | 198/465 (42.6) | |
| 2 | 15/68 (22.1) | 164/1,101 (14.9) | 129/871 (14.8) | 51/465 (11.0) | |
| 3 | 2/68 (2.9) | 14/1,101 (1.3) | 10/871 (1.1) | 4/465 (0.9) | |
| Cardiac tamponade | 3 (3.2) | 26 (1.9) | 18 (1.7) | 10 (1.7) | 0.79 |
| Vascular surgery | 6 (6.3) | 53 (3.9) | 37 (3.5) | 23 (4.0) | 0.59 |
| Any cardiac surgery | 2 (2.1) | 20 (1.5) | 10 (1.0) | 3 (0.5) | 0.22 |
| Surgical aortic valve replacement | 1 (1.1) | 17 (1.3) | 9 (0.9) | 3 (0.5) | 0.48 |
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