Clinical outcomes after transcatheter aortic valve replacement stratified by hemoglobin levels: A retrospective cohort pilot study

Retaj Al Haroun; Mohammed Al Jarallah; Rajesh Rajan; Raja Dashti; Nader Alasousi; Vladimir Kotevski; Ahmed Said Taha Mousa; Joud Al Balool; Gary Tse; Kobalava Davidovna Zhanna; Ahmad Al-Saber; Parul Setiya; Peter A Brady; Adham Hassan Ali Almowafy

doi:10.4103/ACCJ.ACCJ_19_22

ORIGINAL ARTICLE

Year : 2022 | Volume : 4 | Issue : 2 | Page : 66-70

Clinical outcomes after transcatheter aortic valve replacement stratified by hemoglobin levels: A retrospective cohort pilot study

Retaj Al Haroun¹, Mohammed Al Jarallah², Rajesh Rajan³, Raja Dashti², Nader Alasousi², Vladimir Kotevski², Ahmed Said Taha Mousa², Joud Al Balool⁴, Gary Tse⁵, Kobalava Davidovna Zhanna⁶, Ahmad Al-Saber⁷, Parul Setiya⁸, Peter A Brady⁹, Adham Hassan Ali Almowafy²
¹ Department of Medicine, Faculty of Medicine, Royal College of Surgeons, Dublin, Ireland
² Department of Cardiology, Sabah Al Ahmed Cardiac Centre, Al Amiri Hospital, Kuwait City, Kuwait
³ Department of Cardiology, Sabah Al Ahmed Cardiac Centre, Al Amiri Hospital, Kuwait City, Kuwait; Department of Internal Medicine with the Subspecialty of Cardiology and Functional Diagnostics Named after V.S. Moiseev, Institute of Medicine, Peoples' Friendship University of Russia (RUDN University), Moscow, Russia
⁴ Department of Medicine, Faculty of Medicine, Kuwait University, Jabriya, Kuwait
⁵ Cardiovascular Analytics Group, Hong Kong; Department of Cardiology, Tianjin Key Laboratory of Ionic-Molecular Function of Cardiovascular Disease, Tianjin Institute of Cardiology, Second Hospital of Tianjin Medical University, Tianjin, China
⁶ Department of Internal Medicine with the Subspecialty of Cardiology and Functional Diagnostics Named after V.S. Moiseev, Institute of Medicine, Peoples' Friendship University of Russia (RUDN University), Moscow, Russia
⁷ Department of Mathematics and Statistics, University of Strathclyde, Glasgow, United Kingdom
⁸ Department of Agrometeorology, College of Agriculture, G.B. Pant University of Agriculture and Technology, Pantnagar, Uttarakhand, India
⁹ Department of Cardiology, Illinois Masonic Medical Center, Chicago, IL, USA

Date of Submission	17-Sep-2022
Date of Decision	17-Oct-2022
Date of Acceptance	27-Oct-2022
Date of Web Publication	17-Nov-2022

Correspondence Address:
Dr. Rajesh Rajan
Department of Cardiology, Sabah Al Ahmed Cardiac Centre, Al Amiri Hospital, Kuwait City - 15003

Source of Support: None, Conflict of Interest: None

DOI: 10.4103/ACCJ.ACCJ_19_22

Abstract

Background: Anemia is a prevalent comorbidity in patients undergoing aortic valve replacement. Objectives: The objectives of this study were to define baseline parameters of patients with severe aortic stenosis (AS) undergoing transcatheter aortic valve replacement (TAVR) to determine procedural risk and mortality outcomes stratified by hemoglobin (Hb) levels. Methods: Retrospective study of a population of patients with severe AS undergoing TAVR with the Edwards SAPIEN 3 valve between 2018 and 2021 at Sabah Al-Ahmad Cardiac Centre, Al Amiri Hospital, Kuwait. Two cohorts were identified based on Hb level: Hb <13 and Hb ≥13 g/dl. Results: A total of 61 patients were included. The mean age was 73.5 ± 9.0 years, with a higher prevalence of females. The cohort with lower Hb had lower body surface area (2.0 ± 0.1 vs. 1.8 ± 0.2, P = 0.035) and bioprosthesis size (26.5 ± 1.8 vs. 24.4 ± 1.8, P = 0.001). Based on echocardiography, patients with higher Hb levels had a higher prevalence of aortic regurgitation in addition to stenosis (P = 0.029). Conclusions: Baseline anemia is a common comorbidity in patients with severe AS undergoing TAVR. However, in terms of procedural outcomes and mortality, Hb levels were not a predictor of post-TAVR complications or in-hospital death.

Keywords: Anemia, aortic stenosis, hemoglobin, transcatheter aortic valve replacement

How to cite this article:
Al Haroun R, Al Jarallah M, Rajan R, Dashti R, Alasousi N, Kotevski V, Taha Mousa AS, Al Balool J, Tse G, Zhanna KD, Al-Saber A, Setiya P, Brady PA, Ali Almowafy AH. Clinical outcomes after transcatheter aortic valve replacement stratified by hemoglobin levels: A retrospective cohort pilot study. Ann Clin Cardiol 2022;4:66-70

How to cite this URL:
Al Haroun R, Al Jarallah M, Rajan R, Dashti R, Alasousi N, Kotevski V, Taha Mousa AS, Al Balool J, Tse G, Zhanna KD, Al-Saber A, Setiya P, Brady PA, Ali Almowafy AH. Clinical outcomes after transcatheter aortic valve replacement stratified by hemoglobin levels: A retrospective cohort pilot study. Ann Clin Cardiol [serial online] 2022 [cited 2023 Jun 4];4:66-70. Available from: http://www.onlineacc.org/text.asp?2022/4/2/66/361487

Introduction

Aortic stenosis (AS) is the most common valvular abnormality in the elderly and contributes to morbidity and mortality in this population.^[1],[2] Often other medical conditions coexist such that traditional surgical aortic valve replacement is deemed to be high risk.^[3] In these higher risk patients, transcatheter aortic valve replacement (TAVR) has been widely adopted.^[4] Baseline medical comorbidities heavily contribute to all procedural outcomes, and thereby, their identification and treatment are prompt in the management of a complex pathology such as AS.^[5] Anemia is a prevalent comorbidity in patients undergoing aortic valve replacement.^[6] Contributing factors include aging, anticoagulant therapy, and acquired coagulopathy.^[7] The additive burden of low hemoglobin (Hb) levels further limits the oxygen supply additionally induced by the valvular obstruction, potentially worsening their overall symptomatology and survival.^[8] Prior studies on elderly cohorts have delineated an increased risk of mortality risk in patients with anemia.^[9] Notably, low Hb levels (Hb <13 in males and Hb <12 in females) confer an increased risk of short-term mortality following TAVR.^[10] Since baseline anemia is prevalent in patients undergoing TAVR,^[11] it is essential to distinguish prognostic parameters implicated in the overall procedural outcomes. Therefore, this study aims to define baseline characteristics, echocardiographic, and CT parameters of patients with low Hb levels along with their overall procedural complications and mortality.

Methods

A retrospective study of patients with severe AS undergoing TAVR between 2018 and 2021 with the Edwards SAPIEN 3 valve in Sabah Al-Ahmad Cardiac Centre, Al Amiri Hospital, Kuwait. Patient demographics including pre-, intra-, and postprocedural data were included in the study. Patients were grouped into two groups based on preoperative Hb level: Hb <13 g/dl and Hb ≥13 g/dl. Analysis of patients' baseline characteristics, electrocardiographic, and echocardiographic parameters including peak gradient (PG), peak aortic velocity (V_max), mean pressure gradient, aortic valve area, and the presence of left ventricular hypertrophy or other valvular lesions were additionally explored. In terms of postoperative outcomes, conduction disturbances, pacemaker implantation, and in-hospital mortality following TAVR were captured. The ethics committee at the Ministry of Health approved the study protocol.

Statistical analysis

Baseline characteristics of patients were presented as mean ± standard deviation for continuous variables, and frequency with percentages for categorical variables. Cross-sectional associations of demographic, medical, and laboratory factors with Hb cohort were performed using χ² analysis or analysis of variance as appropriate. P =0.05 was considered to examine the significance of the test. The statistical analysis was performed using Jamovi software.

Results

Clinical and demographic characteristics are shown in [Table 1]. A total of 61 patients were included, of who 66% were male. A significant difference was observed in male and female patients for blood Hb levels (P < 0.001). Approximately 76% (n = 38) of the female patients had Hb levels <13, while 82% (n = 9) of male patients had Hb levels more than 13. Further, a noticeable difference was observed between the Hb cohorts with respect to the body surface area (BSA). Patients under the cohort Hb >13 had a mean BSA of 2.0 ± 0.1 ranging from 1.8 to 2.2, and those under the cohort Hb <13 had a mean BSA of 1.8 ± 0.2 ranging from 1.4 to 2.3. In addition, a significant difference was observed in the mean bioprosthesis size among the two subgroups (P ≤ 0.001).

Table 1: Demographic and clinical characteristics of the study population (n=61)

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[Table 2] summarizes the comparison of echocardiographic parameters stratified by Hb levels. There was a significant association between the presence of aortic regurgitation and higher Hb level. This was noted in around 55% (n = 6) of patients with Hb >13 and 22% (n = 11) with Hb <13; other echocardiographic parameters did not differ between the two subgroups.

Table 2: Baseline echocardiographic parameters

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[Table 3] demonstrates the association of baseline and post-TAVR electrocardiographic findings stratified by Hb levels. No difference in baseline ECG was observed between subgroups (P > 0.05). Post-TAVR conduction disturbances were observed in both subgroups, with a higher trend toward complete heart block in patients with lower Hb. Other conduction disturbances encountered in patients with Hb <13 included left (26.6%) and right bundle branch block (6%), first- (6%) and second-degree heart block (2%), along with bifasicular block (2.%), and atrial fibrillation (8%).

Table 3: Baseline and posttranscatheter aortic valve replacement electrocardiographic parameters

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A comparison of baseline laboratory findings of the two subgroups is demonstrated in [Table 4]. A remarkable difference was observed between the cohort Hb >13 and Hb <13 for the laboratory parameters troponin I (1.4 ± 1.8 vs. 0.1 ± 0.4) and calcium (2.2 ± 0.0 vs. 2.4 ± 0.1). Moreover, the analysis revealed no significant mean difference among the cohort with respect to other laboratory parameters. Baseline computed tomography (CT) parameters in patients with different Hb cutoff values are analyzed in [Table 5]. Results reveal a statistically significant difference in the sinotubular junction diam (28.0 ± 3.9 vs. 25.1 ± 3.1, P = 0.040) and area of sinus of Valsalva (940.6 ± 197.1 vs. 688.1 ± 173.9, P = 0.005) in patients with lower Hb levels (Hb <13). Other CT parameters did not significantly differ in the two subgroups.

Table 4: Baseline laboratory values

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Table 5: Preprocedural multidetector computed tomography assessment

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Discussion

The main findings of this study are that periprocedural anemia is common in patients undergoing TAVR for severe AS but does not contribute to worse procedural outcomes. A secondary finding was that most patients who were anemic were more likely female and were more likely to receive a smaller valve. The presence of aortic regurgitation was significantly associated with higher Hb levels.

Previous studies report the prevalence of anemia in patients undergoing TAVR between 40% and 60%^{[12],[13],[14],[15]} [Table 6]. Our cohort revealed a larger proportion of patients with anemia, which can be attributed to a higher proportion of female patients (65.6%) in our study sample. Conduction disturbances induced by TAVR did not significantly between the two subgroups, however, a higher trend of complete heart block was observed in patients with anemia. Permanent pacemaker implantation was required in 14.0% of patients with low Hb levels, delineating a higher trend of conduction disturbances in such patients. The association of conduction disturbances and anemia was established in a cohort of patients undergoing TAVR, with a higher incidence of transient conduction disturbances in patients at lower Hb levels.^[16] Such complications may be due to the proximity of the aortic valve and conduction system along the interventricular system, although the role of anemia is not yet established.^[17]

Table 6: Results from different cohorts on the association of hemoglobin levels in AS patients undergoing transcatheter aortic valve replacement and associated mortality

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The prognostic impact of low Hb levels has been previously explored, with varying results across different cohorts. In the OCEAN-TAVI registry enrolling 2588 AS patients undergoing TAVR, anemia was independently associated with 2-year mortality following the procedure.^[18] Remarkably, anemic patients had a higher in-hospital mortality (4.0%) when compared to patients with higher Hb levels (2.0%), (P < 0.001). This trend was also evident at 2-year all-cause and cardiovascular-related mortality. This association was further replicated in the WIN-TAVI registry, which enrolled 877 female patients undergoing TAVR, with results revealing increased mortality rates at 1 year.^[19] These results address gender differences in TAVR-related outcomes, given the higher proportion of female patients with anemia. Interestingly, an increase in mortality was observed with every 1 gram decrease in Hb levels, delineating the essence of periprocedural management of anemia. Such data allow risk stratification of patients before TAVR, using specific Hb cutoff values to predict prognosis, thereby implying the necessity for prior management.

Although strict guidelines on the management of baseline anemia before TAVR are lacking, recent studies have suggested the value of periprocedural optimization of Hb levels. Current approaches involve blood conservation strategies, iron supplementation, and erythropoiesis-stimulating agents, along with transfusion protocols.^[20] In a cohort of 239 patients evaluated for anemia, pre-TAVR iron and erythropoietin administration substantially reduced blood transfusion rates to 15.3% (P < 0.001).^[21] The implementation of a blood conservation clinic as part of the routine preparation of patients before TAVR thereby can potentially yield beneficial outcomes.

Limitations of our study include smaller sample size and statistical power. In addition, the retrospective nature of the study additionally contributes to the lack of long-term follow-up and detection of out-of-hospital mortality post-TAVR.

Conclusions

Baseline anemia is common in patients with severe AS undergoing TAVR. However, reduced Hb was not a predictor of in-hospital mortality following TAVR.

Financial support and sponsorship

Nil.

Conflicts of interest

There are no conflicts of interest.

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