Abstract
Background
Pulmonary function tests to estimate force vital capacity (FVC) and forced expiratory volume in the first second (FEV 1 ) have increasingly been used in patients evaluated for transcatheter aortic valve implantation (TAVI). The impact of obstructive versus restrictive lung disease on mortality remains unclear. The authors sought to identify differences in survival in patients with 2 distinct pulmonary function patterns (obstruction vs. restriction).
Methods
The authors retrospectively analyzed all patients with abnormal FEV 1 (lower than 80% of predicted) detected on the pulmonary function tests prior to TAVI from May 2011 to November 2014. Patients were divided into a group with obstructive pattern (FEV 1 /FVC < 70% of predicted) and a group with restrictive pattern (FEV 1 /FVC > 70% of predicted). Cox proportional hazards regression was used to explore the impact of FEV 1 on mortality.
Results
A total of 94 patients were included in this analysis. Forty-one percent (n = 38) had obstructive pattern, and 59% (n = 56) had restrictive pattern. FEV 1 values were similar between both groups (43 ± 19 vs. 42 ± 26, p = 0.89). Both groups had similar rates of in-hospital, 30-day, and 1-year mortality. FEV 1 was not a correlate for 1-year mortality. Patients with pulmonary obstructive and restrictive patters had similar rates of mortality. Moreover, FEV 1 value is not a correlate for 1-year mortality.
Conclusion
In the current era, the pattern on pulmonary function tests and FEV 1 values should not influence the decision on whom to offer a transcatheter option for their severe valvular disease.
1
Introduction
Spirometric lung volume measurement has increasingly been used in the screening of patients undergoing Transcatheter Aortic Valve Implantation (TAVI) because lung disease is considered a risk for morbidity and mortality after surgical aortic valve surgery . In fact, the overall estimated incidence of chronic lung disease in patients referred for TAVI is as high as 43% .
In patients with chronic lung disease, the Global Initiative for Chronic Obstructive Lung Disease fixed-ratio spirometric criteria describe two district patterns. Restriction is defined as force expiratory volume in the first second (FEV 1 ) < 80% of predicted and an FEV 1 /force vital capacity (FVC) ratio (FEV 1 /FVC) > 0.7. Obstructive pattern is defined as an FEV 1 < 80% and an FEV 1 /FVC < 0.7 .
Previously, Dvir et al. demonstrated that patients with chronic lung disease undergoing TAVI had worse outcomes than patients without lung disease. However, this study stratified chronic lung disease based on FEV 1 alone, without examining the impact of restriction and obstruction patterns. Identifying restriction is important; restrictive pattern on spirometry is associated with functional limitations, fair or poor self-reported health status, reduced physical performance, and physical impairment in older adults . Moreover, data suggest that restriction is associated with higher mortality in the elderly and deserves the same attention paid to an obstructive pattern .
The primary objective of this study was to identify differences in survival in patients with restriction and obstruction pattern on screening spirometry. Also, the authors aimed to identify the predictive value of FEV 1 on mortality in patients undergoing TAVI.
2
Methods
From May 2007 to November 2014, 94 consecutive patients with severe symptomatic aortic stenosis (AS) and reduced FEV 1 who underwent TAVI were included in this retrospective study. In this study, the authors included all patients FEV 1 lower than 80% of predicted. Patients were divided into two groups (restriction vs. obstruction) according to the pattern on the spirometric analysis. All patients were evaluated according to protocol by the multidisciplinary heart team at the authors’ institution. The heart team was composed of interventional cardiologists, general cardiologists, and cardiac surgeons who determined the eligibility and surgical risk of each patient.
The pre-TAVI evaluation was performed with coronary angiography to detect significant coronary stenosis; contrast computed tomography with standard post-processing reconstructions for aorto-iliac sizing evaluation; and transthoracic echocardiography for detailed left ventricular outflow tract measurement, aortic valve peak velocity, mean gradient, aortic valve area, dimensionless index, left ventricular function, and estimation of systolic pulmonary pressures. Additionally, spirometry was performed to measure lung volumes, in particular, the force FEV 1 and FVC.
All procedures were performed under conscious sedation or general anesthesia provided by a cardiac anesthesiologist in a hybrid catheterization laboratory. Anesthesia type was chosen on a case-by-case basis. The femoral artery was accessed percutaneously or by surgical cut-down. In the first case, the arteriotomy site was pre-closed with a Prostar or 2 Perclose 6Fr suture device (Abbott Vascular, Redwood City, CA). The transapical access was obtained via lateral thoracotomy by an experienced cardiovascular surgeon. After successful TAVI, antiplatelet therapy consisted of clopidogrel 75 mg and aspirin 81 mg for 3 to 6 months.
Demographic, clinical, imaging, and follow-up data were prospectively collected and entered into a registry by an independent cardiologist from the MedStar Cardiovascular Research Network at MedStar Washington Hospital Center, located in Washington, DC. Deaths were confirmed using the Social Security Death Index database and by careful inspection of death certificates and contacting patients at defined time intervals.
All definitions of clinical end points used (in-hospital death, 30-day and 1-year all-cause mortality, stroke, vascular complications, bleeding complications, and acute kidney injury) were in concordance with the Valve Academic Research Consortium-2 (VARC-2) definitions . For this study, the spirometric data were analyzed. Pulmonary restriction pattern was defined as FEV 1 /FVC ratio > 0.7, and pulmonary obstruction was defined as FEV 1 /FVC < 0.7. Aortic regurgitation post TAVI, pacemaker implantation, and new onset post op atrial fibrillation (AF) were also collected prospectively during the index hospitalization.
The study complied with the principles of the Declaration of Helsinki regarding investigation in humans and was approved by the institutional review board of MedStar Washington Hospital Center (Washington, DC).
Statistical analyses were performed using SAS 9.2 (SAS Institute, Cary, NC). Continuous variables are expressed as mean ± SD for normally distributed variables. Categorical variables are expressed as percentages. Analyses of the differences between the two groups were performed using the chi-square or Fisher exact test for categorical variables. Cox proportional hazard analysis was performed to detect predictors of 1-year all-cause mortality. Variables were selected on the basis of overall clinical relevance. Variables included were gender, age, diabetes mellitus, hypertension, prior AF, left ventricular ejection fraction, prior coronary bypass surgery, chronic obstructive lung disease, chronic kidney disease, peripheral vascular disease, Society of Thoracic Surgeons score, transfemoral access, prior cancer, post-operative new onset AF, post-TAVI pacemaker implantation, post-TAVI moderate aortic regurgitation (AR), VARC-2 major vascular complication, VARC-2 life-threatening bleeding complication, VARC-2 major bleeding, in-hospital stroke, and FEV 1 . The results are presented as hazard ratios (HRs) with their 95% confidence intervals (CIs) and p values. Because of the small number of events, only the univariate model is presented at 12 months. Death-free survival rates of the overall population and in selected subgroups were calculated using the Kaplan–Meier method. The log-rank test was used to compare the differences in curves among groups. A p value of ≤ 0.05 was considered to be statistically significant.
2
Methods
From May 2007 to November 2014, 94 consecutive patients with severe symptomatic aortic stenosis (AS) and reduced FEV 1 who underwent TAVI were included in this retrospective study. In this study, the authors included all patients FEV 1 lower than 80% of predicted. Patients were divided into two groups (restriction vs. obstruction) according to the pattern on the spirometric analysis. All patients were evaluated according to protocol by the multidisciplinary heart team at the authors’ institution. The heart team was composed of interventional cardiologists, general cardiologists, and cardiac surgeons who determined the eligibility and surgical risk of each patient.
The pre-TAVI evaluation was performed with coronary angiography to detect significant coronary stenosis; contrast computed tomography with standard post-processing reconstructions for aorto-iliac sizing evaluation; and transthoracic echocardiography for detailed left ventricular outflow tract measurement, aortic valve peak velocity, mean gradient, aortic valve area, dimensionless index, left ventricular function, and estimation of systolic pulmonary pressures. Additionally, spirometry was performed to measure lung volumes, in particular, the force FEV 1 and FVC.
All procedures were performed under conscious sedation or general anesthesia provided by a cardiac anesthesiologist in a hybrid catheterization laboratory. Anesthesia type was chosen on a case-by-case basis. The femoral artery was accessed percutaneously or by surgical cut-down. In the first case, the arteriotomy site was pre-closed with a Prostar or 2 Perclose 6Fr suture device (Abbott Vascular, Redwood City, CA). The transapical access was obtained via lateral thoracotomy by an experienced cardiovascular surgeon. After successful TAVI, antiplatelet therapy consisted of clopidogrel 75 mg and aspirin 81 mg for 3 to 6 months.
Demographic, clinical, imaging, and follow-up data were prospectively collected and entered into a registry by an independent cardiologist from the MedStar Cardiovascular Research Network at MedStar Washington Hospital Center, located in Washington, DC. Deaths were confirmed using the Social Security Death Index database and by careful inspection of death certificates and contacting patients at defined time intervals.
All definitions of clinical end points used (in-hospital death, 30-day and 1-year all-cause mortality, stroke, vascular complications, bleeding complications, and acute kidney injury) were in concordance with the Valve Academic Research Consortium-2 (VARC-2) definitions . For this study, the spirometric data were analyzed. Pulmonary restriction pattern was defined as FEV 1 /FVC ratio > 0.7, and pulmonary obstruction was defined as FEV 1 /FVC < 0.7. Aortic regurgitation post TAVI, pacemaker implantation, and new onset post op atrial fibrillation (AF) were also collected prospectively during the index hospitalization.
The study complied with the principles of the Declaration of Helsinki regarding investigation in humans and was approved by the institutional review board of MedStar Washington Hospital Center (Washington, DC).
Statistical analyses were performed using SAS 9.2 (SAS Institute, Cary, NC). Continuous variables are expressed as mean ± SD for normally distributed variables. Categorical variables are expressed as percentages. Analyses of the differences between the two groups were performed using the chi-square or Fisher exact test for categorical variables. Cox proportional hazard analysis was performed to detect predictors of 1-year all-cause mortality. Variables were selected on the basis of overall clinical relevance. Variables included were gender, age, diabetes mellitus, hypertension, prior AF, left ventricular ejection fraction, prior coronary bypass surgery, chronic obstructive lung disease, chronic kidney disease, peripheral vascular disease, Society of Thoracic Surgeons score, transfemoral access, prior cancer, post-operative new onset AF, post-TAVI pacemaker implantation, post-TAVI moderate aortic regurgitation (AR), VARC-2 major vascular complication, VARC-2 life-threatening bleeding complication, VARC-2 major bleeding, in-hospital stroke, and FEV 1 . The results are presented as hazard ratios (HRs) with their 95% confidence intervals (CIs) and p values. Because of the small number of events, only the univariate model is presented at 12 months. Death-free survival rates of the overall population and in selected subgroups were calculated using the Kaplan–Meier method. The log-rank test was used to compare the differences in curves among groups. A p value of ≤ 0.05 was considered to be statistically significant.
3
Results
A total of 94 patients were included. Of the 94 patients, 56 (59%) had a restrictive pattern and 38 (41%) an obstructive pattern. The average age of the entire population was 80 ± 8 years. Patients with restrictive pattern had a higher prevalence of diabetes (39% vs. 15%, p = 0.02), particularly insulin-dependent diabetes (19% vs. 3%, p = 0.04). However, this group had a strong trend toward lower rates of prior AF (35% vs. 50%, p = 0.07). There was no significant difference in mean FEV 1 values between the restrictive versus the obstructive pattern groups (42 ± 26 vs. 43 ± 19, p = 0.89). The prevalence of other co-morbid conditions was statistically similar between restriction and obstruction pattern groups. The patients’ baseline characteristics and pre- and post-procedural echocardiographic assessments are listed in Table 1 . Left ventricular ejection fraction was similar in the restriction and obstruction groups (50 ± 14% vs. 53 ± 14% p = 0.32). The aortic valve area and mean gradient measurement were also comparable: (0.67 ± 0.1 cm 2 vs. 0.68 ± 0.1 cm 2 , p = 0.83 and 44 ± 14 mmHg vs. 48 ± 12 mmHg, p = 0.14). Eighty-five percent of patients in the restriction group underwent TAVI via transfemoral approach, and 73% of patients in the obstruction group (p = 0.14) underwent this approach. In contrast, 12.5% had TAVI via transapical approach in the restriction group versus 21% in the obstruction group (p = 0.26). Seventy-four percent were deemed inoperable/extreme risk, and 26% were deemed high-risk. The proportion of inoperable and high-risk patients was distributed equally between groups. Procedural outcomes are outlined in Table 2 .
| Variable | Obstruction (n = 38) | Restriction (n = 56) | p value |
|---|---|---|---|
| Age (years) | 81 ± 6 | 80 ± 9 | 0.84 |
| Men | 21(55%) | 28 (50%) | 0.61 |
| Mean Society of Thoracic Surgeons score | 8.5 ± 3.5 | 8.3 ± 5.2 | 0.86 |
| BMI (m 2 ) | 28 ± 5 | 30 ± 7 | 0.16 |
| Hypertension | 26 (68%) | 47 (83%) | 0.17 |
| Diabetes mellitus | 6 (15%) | 22 (39%) | 0.02 |
| Hyperlipidemia | 24 (63%) | 39 (69%) | 0.87 |
| Peripheral arterial disease | 12 (31%) | 13(23%) | 0.27 |
| Prior coronary artery bypass surgery | 7 (18%) | 17 (30%) | 0.26 |
| Prior percutaneous coronary intervention | 12 (31%) | 15 (26%) | 0.44 |
| Atrial fibrillation/atrial flutter | 19 (50%) | 20 (35%) | 0.07 |
| Prior myocardial infarction | 6 (18%) | 13 (23%) | 0.52 |
| Chronic kidney disease | 11 (28%) | 20 (35%) | 0.68 |
| Hemodialysis | 0 (0%) | 7 (12%) | 0.04 |
| FEV1 | 43 ± 19 | 42 ± 26 | 0.89 |
| Pre-procedural echocardiogram | |||
| Mean left ventricular ejection fraction (%) | 53 ± 14 | 50 ± 14 | 0.32 |
| Mean transvalvular gradient (mm Hg) | 48 ± 12 | 44 ± 10 | 0.14 |
| Peak transvalvular gradient (mm Hg) | 73 ± 14 | 67 ± 15 | 0.07 |
| Aortic valve area (cm 2 ) | 0.68 ± 0.1 | 0.67 ± 0.1 | 0.83 |
| Peak aortic velocity (m/s) | 4.38 ± 0.5 | 4.19 ± 0.5 | 0.11 |
| Mean pulmonary artery systolic pressure | 43 ± 16 | 46 ± 14 | 0.34 |
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