Better outcomes have been reported after percutaneous cardiac intervention in obese patients (“obesity paradox”). However, limited information is available on the effect of the body mass index on the outcomes after transcatheter aortic valve implantation (TAVI). We, therefore, sought to determine the effect of the body mass index on the short- and long-term outcomes in patients who underwent TAVI. The population consisted of 940 patients, of whom 25 (2.7%) were underweight, 384 had a (40.9%) normal weight, 372 (39.6%) were overweight, and 159 (16.9%) were obese. Overall, the obese patients were younger (79.7 ± 6.4 years vs 81.7 ± 7.3 and 80.8 ± 7.0 years, p = 0.008) and had a greater prevalence of preserved left ventricular and renal function. On univariate analysis, obese patients had a greater incidence of minor stroke (1.3% vs 0 and 0.3%, p = 0.03), minor vascular complications (15.7% vs 9.1% and 11.6%, p = 0.028) and acute kidney injury stage I (23.3% vs 10.7% and 16.1%, p <0.001). After adjustment, body mass index, as a continuous variable, was associated with a lower risk of mortality at 30 days (odds ratio 0.93, 95% confidence interval 0.86 to 0.98, p = 0.023) and no effect on survival after discharge (hazard ratio 1.01, 95% confidence interval 0.96 to 1.07, p = 0.73). In conclusion, obesity was associated with a greater incidence of minor, but no major, perioperative complications after TAVI. After adjustment, obesity was associated with a lower risk of 30-day mortality and had no adverse effect on mortality after discharge, underscoring the “obesity paradox” in patients undergoing TAVI.
Transcatheter aortic valve implantation (TAVI) has become an established treatment of patients with aortic stenosis who are at high risk of surgical aortic valve replacement. Given the endemic nature of obesity in developed countries, one might expect an increasing number of such patients being referred for TAVI. However, although obesity has been associated with greater mortality in the general population and in patients with coronary artery disease, a number of studies have revealed better outcomes after percutaneous and surgical coronary intervention and after surgical aortic valve replacement, termed the “obesity paradox.” Patients who currently undergo TAVI are older and have more co-morbid conditions than those who undergo percutaneous coronary intervention or cardiac surgery. This, combined with the use of large indwelling delivery catheters, could expose obese patients to a particular high risk of perioperative complications. Currently, no information is available on an eventual protective or adverse effect of body weight on the procedural and long-term outcomes in patients undergoing TAVI, which was the subject of the present study.
Methods
The Pooled-RotterdAm-Milano-Toulouse In Collaboration Plus (PRAGMATIC Plus) Initiative is a collaboration of 4 European institutions with established TAVI experience. The baseline patient characteristics, procedural details, and clinical outcomes data from a series of 944 consecutive patients were prospectively collected from San Raffaele Scientific Institute, Milan, Italy (n = 330); Clinique Pasteur, Toulouse, France (n = 224); Thoraxcenter, Erasmus Medical Center, Rotterdam, The Netherlands (n = 206); and Hôpital Rangueil, Toulouse, France (n = 184). After the Valve Academic Research Consortium (VARC) consensus document was made public, the VARC end point definitions were adopted, and the respective local databases were modified accordingly. All data were then pooled into a dedicated global multicenter database, after which a post hoc analysis was performed. Patient eligibility for TAVI has been previously described and is comparable across the 4 centers. All patients with symptomatic severe aortic stenosis who underwent TAVI had been judged to be at high operative risk by multidisciplinary heart team consensus. The body mass index (BMI) was defined as the weight in kilograms divided by the square of the height in meters. The weight and height of all the patients were collected at hospital admission before the TAVI procedure. Categorization of the BMI was adopted from the World Health Organization and National Institutes of Health and defined as underweight (<18.5 kg/m 2 ), normal weight (18.5 to 24.9 kg/m 2 ), overweight (25.0 to 30.0 kg/m 2 ), or obese (>30 kg/m 2 ). The primary end point of the present study was all-cause mortality at 30 days and during follow-up. The secondary end points included death, myocardial infarction, cerebrovascular complications, vascular and bleeding complications, and acute kidney injury (AKI), in accordance with the VARC end point definitions.
After hospital discharge, mortality data were collected by contacting the civil registries or the referring physician or general practitioner. Follow-up data were complete for 99.5% of the patients who survived the first 30 days.
Categorical variables are presented as frequencies with percentages and compared using the Pearson’s chi-square test or Fisher’s exact test, as appropriate. To assess the presence of a linear association between BMI and outcome, linear-by-linear association was used. Continuous variables are presented as the mean ± SD in the case of a normal distribution or median and interquartile range in the case of a skewed distribution and compared using analysis of variance. The normality of the distributions was assessed using the Shapiro-Wilks test. Superiority testing was only performed between the normal weight, overweight, and obese groups owing to the low sample size in the underweight group (n = 25). Univariate and multivariate logistic regression analysis was used to assess the effect of BMI on 30-day mortality. Cox proportional hazard regression analysis was performed to determine the relation between BMI (category) and mortality during follow-up. All BMI categories, except for the underweight category, were entered into the model, with the normal weight patients (BMI 18.5 to 24.9 kg/m 2 ) as the reference group. Multivariate analysis was adjusted for all differences in baseline and procedural characteristics (age, gender, diabetes, chronic obstructive pulmonary disease, coronary disease, learning effect (first vs latter ½ of cohort), sheath size (18Fr or 19Fr vs >19Fr), percutaneous versus surgical access, peripheral vascular disease, logistic European System for Cardiac Operative Risk Evaluation (logistic EuroSCORE; [LES]), left ventricular ejection fraction ≤35%, and glomerular filtration rate ≤60 ml/min/1.73 m 2 ). Additionally, univariate and multivariate (logistic or Cox) regression analysis was performed, with BMI as a continuous variable to determine the relation of an increase in 1 kg/m 2 and the primary end point. Survival curves for time-to-event variables were constructed for patients who survived the first 30 days after TAVI (landmark analysis) using Kaplan-Meier estimates and compared using the log-rank test. A 2-sided α level of 0.05 was used for all superiority testing. All statistical analysis were performed using the Statistical Package for Social Sciences software, version 17.0 (SPSS, Chicago, Illinois).
Results
A total of 940 patients with complete information on weight and height were included in the present study. Four patients were excluded because of missing data for either height or weight. The baseline characteristics and procedural details of the population according to the 4 predefined BMI categories are summarized in Tables 1 and 2 . Overall, 57% of the patients were either overweight or obese. The latter constituted 17% of the population. These patients were in general younger, with a greater prevalence of preserved left ventricular systolic and renal function but more diabetes. The first 2 characteristics explained the lower LES (18.7%, IQR: 10.9% to 26.4%]) in obese patients. No differences were seen in the procedural details among the different categories ( Table 2 ).
| Variable | Overall (n = 940) | BMI (kg/m 2 ) | p Value | |||
|---|---|---|---|---|---|---|
| <18.5 (n = 25) | 18.5–24.9 (n = 384) | 25–29.9 (n = 372) | >30 (n = 159) | |||
| Age (yrs) | 81.0 ± 7.03 | 81.4 ± 6.5 | 81.7 ± 7.3 ∗ | 80.8 ± 7.0 | 79.7 ± 6.4 ∗ | 0.008 |
| Men | 506/940 (54%) | 8/25 (32%) | 205/384 (53%) | 228/372 (61%) | 65/159 (41%) | <0.001 |
| Body mass index (kg/m 2 ) | 26.26 ± 4.34 | 17.50 ± 0.88 | 22.54 ± 1.61 | 27.06 ± 1.34 | 33.38 ± 3.48 | <0.001 |
| New York Heart Association class III or IV | 761/938 (81%) | 18/24 (75%) | 305/383 (80%) | 299/372 (80%) | 139/159 (87%) | 0.09 |
| Logistic European System for Cardiac Operative Risk Evaluation | 20.9 (13.0–29.9) | 20.5 (11.9–29.1) | 21.0 (13.8–28.3) | 21.6 (12.9–30.3) | 18.7 (10.9–26.4) | 0.002 |
| Previous cerebrovascular accident | 147/940 (16%) | 2/25 (8%) | 61/384 (16%) | 64/372 (17%) | 20/159 (13%) | 0.41 |
| Previous myocardial infarction | 158/940 (17%) | 3/25 (12%) | 59/384 (15%) | 73/372 (20%) | 23/159 (15%) | 0.20 |
| Previous coronary bypass grafting | 207/940 (22%) | 3/25 (12%) | 69/384 (18%) | 100/372 (27%) | 35/159 (22%) | 0.013 |
| Previous percutaneous coronary intervention | 277/940 (30%) | 4/25 (16%) | 114/384 (30%) | 121/372 (33%) | 38/159 (24%) | 0.14 |
| Coronary artery disease | 425/940 (45%) | 6/25 (24%) | 164/384 (43%) | 193/372 (52%) | 62/159 (39%) | 0.007 |
| Diabetes mellitus | 268/940 (29%) | 6/25 (24%) | 86/384 (22%) | 107/372 (29%) | 69/159 (43%) | <0.001 |
| Hypertension | 656/940 (70%) | 14/25 (56%) | 265/384 (69%) | 265/372 (71%) | 112/159 (70%) | 0.80 |
| Serum creatinine level (μmol/L) | 99.0 (72.4–125.7) | 83.1 (67.2–99.0) | 99.5 (74.1–124.9) | 101.3 (70.0–132.6) | 108.1 (87.3–128.8) | 0.06 |
| Glomerular filtration rate (ml/min/1.73 m 2 ) † | 57.6 (41.0–74.2) | 71.2 (54.8–87.6) | 56.9 (41.1–72.6) | 57.3 (39.3–75.3) | 59.9 (45.2–74.5) | 0.57 |
| Glomerular filtration rate <60 ml/min/1.73 m 2 | 591/937 (63%) | 20/25 (80%) | 275/383 (72%) | 221/372 (59%) | 75/157 (48%) | <0.001 |
| Chronic obstructive pulmonary disease | 323/940 (34%) | 8/25 (32%) | 128/384 (33%) | 126/372 (34%) | 61/159 (38%) | 0.51 |
| Peripheral vascular disease | 234/936 (25%) | 8/24 (33%) | 96/383 (25%) | 100/370 (27%) | 30/159 (19%) | 0.14 |
| Permanent pacemaker | 105/940 (11%) | 0/25 | 49/384 (13%) | 46/372 (12%) | 10/159 (6%) | 0.08 |
| Echocardiography | ||||||
| Aortic valve annulus (mm) | 23.11 ± 2.11 | 22.21 ± 2.30 | 23.02 ± 2.26 | 23.30 ± 1.97 | 23.01 ± 1.95 | 0.15 |
| Left ventricular ejection fraction ≤35% | 160/940 (17.0) | 6/25 (24%) | 79/384 (21%) | 57/372 (15%) | 18/159 (11%) | 0.019 |
| Aortic valve area (cm 2 ) | 0.71 ± 0.19 | 0.63 ± 0.18 | 0.68 ± 0.19 | 0.73 ± 0.20 ∗ | 0.73 ± 0.19 ∗ | 0.001 |
∗ Statistically significant from each other using Bonferroni’s correction.
† Glomerular filtration rate was calculated using the Modification of Diet in Renal Disease equation.
| Variable | Overall (n = 940) | BMI (kg/m 2 ) | p Value | |||
|---|---|---|---|---|---|---|
| <18.5 (n = 25) | 18.5–24.9 (n = 384) | 25–29.9 (n = 372) | >30 (n = 159) | |||
| Prosthesis type and size | ||||||
| Medtronic CoreValve 26-mm | 152/940 (16%) | 8/25 (32%) | 59/384 (15%) | 59/372 (16%) | 26/159 (16%) | 0.96 |
| Medtronic CoreValve 29-mm | 348/940 (43%) | 5/25 (20%) | 142/384 (37%) | 132/372 (36%) | 69/159 (43%) | 0.22 |
| Medtronic CoreValve 31-mm | 5/940 (1%) | 0/25 | 0/384 | 5/372 (1%) | 0/159 | 0.025 |
| Edwards Sapien 23-mm | 155/940 (17%) | 9/25 (36%) | 74/384 (19%) | 46/372 (12%) | 26/159 (16%) | 0.034 |
| Edwards Sapien 26-mm | 274/940 (29%) | 3/25 (12%) | 106/384 (28%) | 127/372 (34%) | 38/159 (24%) | 0.032 |
| Edwards Sapien 29-mm | 6/940 (1%) | 0/25 | 3/384 (1%) | 3/372 (1%) | 0/159 | 0.53 |
| Sheath size | ||||||
| 18Fr Medtronic | 500/940 (53%) | 11/25 (44%) | 200/384 (52%) | 196/372 (53%) | 93/159 (59%) | 0.37 |
| 18–19Fr Edwards | 242/940 (26%) | 9/25 (36%) | 106/384 (28%) | 88/372 (24%) | 39/159 (25%) | 0.44 |
| >19Fr | 198/940 (21%) | 5/25 (20%) | 78/384 (20%) | 88/372 (24%) | 27/159 (17%) | 0.20 |
| Vascular access | ||||||
| Surgical | ||||||
| Femoral artery | 94/940 (10%) | 2/25 (8%) | 41/384 (11%) | 38/372 (10%) | 13/159 (8%) | 0.67 |
| Subclavian artery | 57/940 (6%) | 0/25 | 27/384 (7%) | 17/372 (5%) | 13/159 (8%) | 0.20 |
| Transapical | 89/940 (10%) | 3/25 (12%) | 38/384 (10%) | 40/372 (11%) | 5/159 (5%) | 0.11 |
| Percutaneous | ||||||
| Femoral artery | 696/940 (74%) | 20/25 (80%) | 277/384 (72%) | 275/372 (74%) | 124/159 (78%) | 0.37 |
| Transaortal | 4/940 (0.4%) | 0/25 | 1/384 (0.3%) | 2/372 (1%) | 1/159 (1%) | 0.78 |
| Therapy-specific results | ||||||
| Concomitant percutaneous coronary intervention | 21/940 (2%) | 0/25 | 9/384 (2%) | 7/372 (2%) | 5/159 (3%) | 0.73 |
| Postimplantation balloon dilation | 115/940 (12%) | 3/25 (12%) | 45/384 (12%) | 47/372 (13%) | 20/159 (13%) | 0.73 |
| Valve-in-valve implantation | 31/940 (3%) | 1/25 (4%) | 13/384 (3%) | 12/372 (3%) | 5/159 (3%) | 0.87 |
| Coronary obstruction | 3/940 (0.3%) | 0/25 | 1/384 (0.3%) | 1/372 (0.3%) | 1/159 (1%) | 0.51 |
The in-hospital outcomes (VARC definitions) are summarized in Table 3 . Obese patients had a greater incidence of minor stroke (1.3% vs 0% and 0.3% in normal weight and overweight patients, respectively; p = 0.03), minor vascular complications (15.7% vs 9.1% and 11.6%, respectively, p = 0.028), and AKI stage I (23.3% vs 10.7% and 16.1%, respectively, p <0.001) Long-term follow-up data were complete for 99.5% of all patients, and follow-up ranged from 1 to 72 months (median 12, interquartile range 6 to 18). Kaplan-Meier estimates of survival after hospital discharge disclosed no difference in survival in the various patient categories (log-rank, p = 0.76; Figure 1 ).
| Overall (n = 940) | BMI (kg/m 2 ) | p Value | ||||
|---|---|---|---|---|---|---|
| <18.5 (n = 25) | 18.5–24.9 (n = 384) | 25–29.9 (n = 372) | >30 (n = 159) | |||
| Device success | 885/940 (94%) | 23/25 (92%) | 362/384 (94%) | 350/372 (94%) | 150/159 (94%) | 1.00 |
| All-cause 30-day or in-hospital death | 68/940 (7%) | 5/25 (20%) | 33/384 (9%) | 21/372 (6%) | 9/159 (6%) | 0.13 |
| Cerebrovascular complication | ||||||
| Major stroke | 22/940 (2%) | 0/25 | 9/384 (2%) | 10/372 (3%) | 3/159 (2%) | 0.86 |
| Minor stroke | 3/940 (0.3%) | 0/25 | 0 | 1/372 (0.3%) | 2/159 (1%) | 0.03 |
| Transient ischemic attack | 13/940 (1%) | 0/25 | 5/384 (1%) | 4/372 (1%) | 4/159 (3%) | 0.40 |
| Myocardial infarction | ||||||
| Periprocedural (<72 h) | 9/940 (1%) | 1/25 (4%) | 3/384 (1%) | 4/372 (1%) | 1/159 (1%) | 0.99 |
| Spontaneous (>72 h) | 6/940 (1%) | 0/25 | 3/384 (1%) | 2/372 (1%) | 1/159 (1%) | 0.77 |
| Bleeding complications | ||||||
| Life-threatening | 129/940 (14%) | 4/25 (16%) | 50/384 (13%) | 56/372 (15%) | 19/159 (12%) | 0.97 |
| Major | 198/940 (21%) | 6/25 (24%) | 73/384 (19%) | 84/372 (23%) | 159/35 (22%) | 0.31 |
| Minor | 102/940 (11%) | 3/25 (12%) | 43/384 (11%) | 37/372 (10%) | 19/159 (12%) | 0.96 |
| Vascular complications | ||||||
| Major | 101/940 (11%) | 3/25 (12%) | 40/384 (10%) | 41/372 (11%) | 17/159 (11%) | 0.87 |
| Minor | 107/940 (11%) | 4/25 (16%) | 35/384 (9%) | 43/372 (12%) | 25/159 (16%) | 0.028 |
| Acute kidney injury | ||||||
| Stage I | 139/940 (15%) | 1/25 (4%) | 41/384 (10%) | 60/372 (16%) | 37/159 (23%) | <0.001 |
| Stage II | 34/940 (4%) | 1/25 (4%) | 12/384 (3%) | 12/372 (3%) | 9/159 (6%) | 0.21 |
| Stage III | 43/939 (5%) | 2/25 (8%) | 17/383 (4%) | 19/372 (5%) | 5/159 (3%) | 0.67 |
| Total hospital stay (days) | 8.0 (5.5–10.5) | 7.0 (4.0–10.0) | 8.0 (5.5–10.5) | 8.0 (5.5–10.5) | 8.0 (5.5–10.5) | 0.84 |
| Red blood cell transfusion required | 363/937 (39%) | 12/25 (48%) | 143/382 (37%) | 144/371 (39%) | 64/159 (40%) | 0.53 |
| Prosthetic valve-associated complication (permanent pacemaker requirement) | 145/938 (16%) | 3/25 (12%) | 54/382 (14%) | 60/372 (16%) | 28/159 (18%) | 0.28 |
| Combined safety end point | 248/940 (26%) | 9/25 (36%) | 101/384 (26%) | 106/372 (29%) | 32/159 (20%) | 0.29 |
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