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 Table of Contents  
Year : 2023  |  Volume : 7  |  Issue : 2  |  Page : 74-79

Retrospective Observational Analysis of Outcomes After Surgical Valve Replacement: A 15 Years' Experience in a Tertiary Care Hospital

1 Department of Cardiology, Hero DMC Heart Institute, Ludhiana, Punjab, India
2 Department of CTVS, Hero DMC Heart Institute, Ludhiana, Punjab, India

Date of Submission19-Sep-2022
Date of Decision25-Oct-2022
Date of Acceptance26-Oct-2022
Date of Web Publication05-Apr-2023

Correspondence Address:
Rohit Tandon
HDHI, Ludhiana, Punjab
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Source of Support: None, Conflict of Interest: None

DOI: 10.4103/jiae.jiae_46_22

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Background: None of the currently available prosthetic valves are comparable to native valves in hemodynamic functions. One has to choose between durability, thrombogenicity, or risk of major bleeds. These questions can be answered effectively with the help of long-term follow-up data. Aims and Objectives: We aimed to assess primary and secondary outcomes in patients who had undergone valve replacement (bioprosthetic or mechanical) over the last 15 years at our institution. Materials and Methods: Retrospective data on clinical outcomes of all patients of valve replacement surgery over the last 15 years was taken. Standardized definitions were used to report primary and secondary outcomes, and appropriate statistical methods were applied to evaluate the data. Results: There were a total of 681 patients (66.7% mechanical and 33.3% bioprosthetic valves) with a median follow-up of 7.5 years. Overall survival rates for bioprosthetic valves for 1,5, and 10 years were 99% and for mechanical valves were 98% and 96% at 5 years and 10 years respectively. Late mortality predictors in the mechanical valve group were pre-operative New York Heart Association (NYHA) class, left ventricular (LV) systolic function, atrial fibrillation, post-operative sub-therapeutic international normalized ratio (INR) values and valve replacement at mitral position. Conclusion: The study showed that mechanical valves had a 96 % survival rate at 10 to 15 years which was dependent upon preoperative NYHA class, preoperative LV functions AF, and postoperative INR values. In contrast, bioprosthetic valves had 99% survival but with a higher incidence of secondary outcomes, mainly in the form of structural valve degeneration.

Keywords: Bioprosthetic, echocardiography, mechanical, rheumatic heart disease

How to cite this article:
Sondh MS, Gupta R, Sachdeva S, Tandon R. Retrospective Observational Analysis of Outcomes After Surgical Valve Replacement: A 15 Years' Experience in a Tertiary Care Hospital. J Indian Acad Echocardiogr Cardiovasc Imaging 2023;7:74-9

How to cite this URL:
Sondh MS, Gupta R, Sachdeva S, Tandon R. Retrospective Observational Analysis of Outcomes After Surgical Valve Replacement: A 15 Years' Experience in a Tertiary Care Hospital. J Indian Acad Echocardiogr Cardiovasc Imaging [serial online] 2023 [cited 2023 Oct 3];7:74-9. Available from: https://jiaecho.org/text.asp?2023/7/2/74/373605

  Introduction Top

Valvular heart disease remains a major cause of cardiovascular mortality and morbidity worldwide. Etiopathologically, rheumatic heart disease, followed by degenerative and ischemic heart diseases are the leading causes of valvular heart disease in our country. Most of these valve lesions ultimately require surgical correction. However, all types of prosthetic valves, whether biological or mechanical, are associated with inherent problems leading to various post-operative complications. These post-operative complications have major implications for managing patients with valvular heart disease, esp. in our country where there are economic challenges and limited infrastructural facilities. Hence, there is a compelling need for real-world data showing a decade-wise comparison of postoperative valve-related outcomes of mechanical and bioprosthetic valves. Unfortunately, no such data is currently available for patients in India. Therefore, this study was sought with the following objectives-

  1. To assess both short-term and long-term complications in patients with prosthetic heart valves
  2. To define the ideal candidate for bioprosthetic or mechanical heart valves.

  Materials and Methods Top

Study design

This study was a retrospective observational analysis of both short-term and long-term outcomes in patients who had undergone valve replacement surgery in the past 15 years at our institution. We collected data from 960 patients, out of which 279 patients were lost to follow-up. Hence, a total of 681 patients were included in the study whose postoperative follow-up data of at least 1 year was available [Figure 1]. Echocardiography was interpreted by a single, level 3 competency-trained sonographer physician, thereby eliminating interobserver variability.
Figure 1: Study design

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Inclusion criteria

Our study included all patients who had undergone valve replacement surgery in the past 15 years at our institution.

Exclusion criteria

The patients who did not meet the follow-up criteria (at least four follow-up visits in the following year after surgery) were excluded from the study. The patients who had undergone double valve replacement were excluded from the study due to the complexities associated with their follow-up, unlike isolated valve replacement patients.

Primary and secondary endpoints

Valve-related mortality of the patients was taken as the primary endpoint, and any significant value-related complication (as described below) was defined as the secondary endpoint.[1]

Early mortality was defined as death occurring within 30 days of surgery. Late mortality was defined as death occurring after 30 days of surgery.

All patients received either bileaflet mechanical valves or stented bioprosthetic valves. All patients with mechanical prostheses or those patients having bioprosthetic valves with atrial fibrillation were anticoagulated with coumadin drugs.

Structural valve deterioration (SVD) was defined on the basis of dysfunction or deterioration of operated valve secondary to wear and tear, fracture leading to leaflet tear, suture line disruption, new chordal rupture, and thickening or retraction of valves, thereby increasing chances of infective endocarditis or thrombosis.

Nonstructural dysfunction was diagnosed on the basis of clinical and echocardiographic evidence of stenosis/regurgitation/hemolysis secondary to pannus formation, residual leak, paravalvular leak, and patient prosthetic mismatch.

Statistical analysis

Data were described in terms of range, mean ± standard deviation, frequencies (number of cases), and relative frequencies (percentages) as appropriate. A comparison of quantitative variables between the study groups was done using the Student's t-test. For comparing categorical data, Chi-square (χ2) test was performed, and Fisher's exact test was used when the expected frequency was <5. Kaplan–Meier analysis was performed to estimate survival in the two groups. A P < 0.05 was considered statistically significant. All statistical calculations were done using Statistical Package for the Social Science version 21.0 (SPSS Inc., Chicago, IL, USA) statistical program for Microsoft Windows. Relative risk (RR) was calculated using the χ2 test.

  Results Top

We studied 681 patients, out of which there were 394 (58%) males and 287 (42%) females. Of these 681 patients, 454 (66.7%) had undergone mechanical valve replacement and 227 (33.3%) bioprosthetic valve replacement. The median follow-up period was 6 years and 8 months in both the groups. The patients who had undergone bioprosthetic valve replacement had a median age of presentation 58 years, whereas those who had undergone mechanical valve replacement were younger, with a median age of presentation being 47 years. The most common indication for mechanical valve replacement was rheumatic heart disease (66%), followed by degenerative valve disease (12%) and congenital heart disease (11%). In comparison, in the bioprosthetic valve group, degenerative valve disease was the commonest indication (40% patients) followed by rheumatic heart disease (28%) and congenital heart disease (11%). Ischemic mitral regurgitation (MR) was the indication for the surgery in 8% patients in the bioprosthetic valve group and 1.7% patients in the mechanical valve group. Aortic aneurysm resection with root repair along with bioprosthetic valve replacement was done in 9.3% of patients. Among the patients requiring bioprosthetic valve replacement, 3.7% were pregnant and had mitral valve disease needing surgery. In 9% of the cases of mechanical valve replacement, the indication was infective endocarditis [Figure 2].
Figure 2: Graphical representation of different indications of valve replacement

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Preoperative factors

In the bioprosthetic valve group, 44% of the patients were in the New York Heart Association (NYHA) class III, 43% were in class II, and 13% were in class IV. Preoperative atrial fibrillation was present in 6%; 21% of the patients had moderate–severe pulmonary artery hypertension and 22% had moderate or severe left ventricular (LV) systolic dysfunction [Table 1].
Table 1: Preoperative characteristics in the study patients

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In the mechanical valve group, 57% of the patients were in NYHA class III, 22% were in class II, and 21% were in class IV. Preoperative atrial fibrillation was in 16% of the patients, whereas 17% had moderate–severe pulmonary artery hypertension and 9% had moderate or severe LV systolic dysfunction.

Primary endpoint

Bioprosthetic valves

Late mortality rate in the bioprosthetic group was 1.7% with valve thrombosis being the earliest cause (at 3 months after surgery) occurring in one patient, prosthetic valve endocarditis in an aortic valve replacement (AVR) patient at 6 months after surgery, and progressive structural valve degeneration in two patients of mitral valve replacement (MVR) who had developed severe MR after 10 and 11 years of surgery, respectively. No case of early mortality (<30 days after surgery) was noted.

Mechanical valves

Late mortality rate in the mechanical valve group was 3.3% with progressive LV systolic dysfunction in six MVR patients and one AVR patient, occurring, as early as 4 months in one patient and 6–8 months in the others. Notably, all of these patients were in NYHA class IV with moderate LV systolic dysfunction preoperatively. Thromboembolism causing cerebrovascular accident was the second-most common cause for late mortality and occurred in six patients who had undergone MVR. It occurred as early as 4th month after surgery in one patient. with the rest of the patients suffering it at 22 months and 3, 4, 7, and 8 years after surgery. Notably, all these patients had missed their physician visits and had sub-therapeutic international normalized ratio (INR) values. Following predictors of late mortality were noted- preoperative NYHA class, LV systolic function, atrial fibrillation, postoperative sub-therapeutic INR values, and valve replacement at mitral position.

Overall survival rates for bioprosthetic valves at 1, 5, and 10 years were 99% and for mechanical valves were 98% at 5 years and 96% at 10 years [Figure 3] and [Figure 4]. No case of early mortality (<30 days after surgery) was noted in either of the two groups.
Figure 3: Survival rates in prosthetic heart valves at different time intervals

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Figure 4: Comparative cumulative hazard for survival in bioprosthetic (B) and mechanical (M) valves showing rise in the event rates after 8 years of valve implantation in the bioprosthetic group

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Secondary endpoints

The most common complication observed in both the groups was pleural effusion.

Bioprosthetic valves

Sixty-eight percent (N = 156) of the patients developed complications in this group. Structural valve degeneration was the most common (53% in the AVR group, 47% in the MVR group), seen in 51% of the patients, followed by paravalvular regurgitation in 12% (60% in the AVR group and 40% in the MVR group), postoperative LV systolic dysfunction in 8%, infective endocarditis in 4%, thromboembolism in 2%, and prosthetic valve thrombosis in 1% of the patients.

Average time for the development of complications

The earliest observed complications were valve thrombosis (within 3 months of surgery) in one patient each from mitral and aortic bioprosthesis and infective endocarditis in a patient with mitral bioprosthesis.

SVD was observed as a late complication at a median follow-up of 7.5 years after surgery. Significant paravalvular regurgitation and progressive postoperative LV systolic dysfunction were observed at 6.5 years after surgery.

Mechanical valves

Thirty-four percent (N = 154) of the patients developed complications. The most frequent complications observed were paravalvular regurgitation, prosthetic valve obstruction, major bleeding, and postoperative LV systolic dysfunction (24%, 24%, 23%, and 19%, respectively). Infrequently observed complications were prosthetic valve endocarditis (2%) and prosthetic valve dehiscence (2%) [Table 2].
Table 2: Comparison of valve related events in mechanical and bioprosthetic heart valves

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Average time for the development of complications

The earliest observed complications were postoperative LV systolic dysfunction and valve dehiscence diagnosed as early as 1 month after surgery. The patient-prosthetic mismatch at the aortic valve level was diagnosed in 11% of the patients as early as 2 months after surgery. Eighty-five percent of these patients developed pannus-related obstruction on follow-up.

Major bleeding events occurred at 2.8 years after surgery with the earliest event occurring at 3 months (upper gastrointestinal bleeding) after valve replacement. Thromboembolism was observed at 3 years after surgery with one patient developing early cerebrovascular accident (within 3 months). [Figure 5] summarizes decade wise comparison of secondary endpoints.
Figure 5: Decade-wise distribution of secondary outcomes in prosthetic heart valves

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Overall analysis of both groups

SVD dominated long-term complications (RR 4.8) in the bioprosthetic group, although overall mortality was higher in the mechanical group (RR 1.19). Prosthetic valve endocarditis was also seen more commonly in the bioprosthetic group (RR 2.2).

Postoperative pacemaker implantation was required more commonly in patients with mechanical valve implantation (RR 1.2), possibly due to a higher incidence of peri-His Bundle edema. Thromboembolic phenomenon was also seen predominantly in patients with mechanical valve replacement (RR 1.35), probably due to a higher incidence of pannus–thrombus combination in patients with subtherapeutic INR. Bleeding complications were more common in patients with mechanical valve replacement (RR 1.5).

In the <25 years and >55 years of age group patients with bioprosthetic valves, there was an early rise in the hazard ratio (as early as 3 years), whereas in the rest of the age groups, there was comparable long-term complication rate (up to 8 years).

  Discussion Top

The outcome of the patients with significant symptomatic valve disease is poor without valve repair or replacement because without intervention, irreversible heart failure may ensue, ultimately leading to death of the patient. Despite recent improvements in valve design and experience with valve repair, there seems to be little reduction in morbidity and mortality in these patients.[2] Surgical mortality depends on the patients' clinical and hemodynamic status, particularly age at presentation, presence of comorbid conditions, LV function, presence or absence of AF, presence of marked pulmonary artery hypertension, and also experience and expertise of the surgical team dictating the immediate surgical risk which does not depend significantly with the choice of the valve. This consideration is particularly important and a challenge for the heart valve care team, especially in the developing countries.

Globally, degenerative and rheumatic valve diseases comprise majority of the valvular heart disease cases. Surgical replacement of these diseased native valves has been the mainstay of treatment. Although mechanical valves appear safe in view of lesser structural degeneration, this advantage is offset by bleeding and thrombotic events. Bioprosthetic valves stand at other end of the spectrum of valve-related events. Although they offer the least thrombogenicity, with time SVD ensues. As concluded by the Veterans Affairs and Edinburg trial,[3] there was increased bleeding associated with mechanical valves and increased reoperation with tissue valves but comparable rates of thromboembolism and endocarditis. The choice of prosthesis for valve replacement is often determined by balancing the risks of anticoagulation and reoperation, and reports of improved durability of biologic prostheses have led to a substantial increase in their use.

Studies comparing bioprosthetic and mechanical mitral valves indicate that patients <65 years of age with bioprosthetic valve have increased rate of reoperation and decreased survival.[4] Recent consensus recommendations favor the use of bioprosthetic heart valves in comparison to mechanical valves with regard to anticoagulation-related events; this choice is getting further complicated due to advancement in percutaneous valve replacement procedures which is being preferred by the younger age group patients.[5],[6],[7] In our study, bioprosthetic valve patients had early SVD as early as 1 year. Furthermore, in the bioprosthetic valves group, SVD presenting as obstruction and/or regurgitation was the dominant limiting factor which also appeared as the most frequent complication irrespective of age and gender. In mechanical valves, valve thrombosis and major bleeds were frequent. Various studies have shown no significant differences between the type of valves in relation to clinical outcomes, hemodynamics, and mortality except in specific patient groups and women of the child-bearing age group, elderly people, patients with high HAS-BLED score, and patients who may require reoperation due to recurring nature of the disease.[8]

A meta-analysis done on porcine and pericardial aortic valves showed that SVD usually starts after 8 years of implantation and increases abruptly after 10 years.[9] In our study too, the hazard ratio increases exponentially after 8 years in the bioprosthetic group [Figure 4].

In young patients, tissue valves develop early calcification as a result of increased turnover of calcium, fatigue-induced lesions, and collagen degeneration. Although promising results have been reported with the newer generation bioprosthetic valves in the younger populations, young age still remains a risk factor for reoperation.

Expectedly, anticoagulation-related bleeding complications were high in the mechanical group which corroborates with earlier studies. In our study, major bleeds occurred mainly in the fifth and sixth decades and lesser in the seventh and eighth decades probably because younger age group patients had been on anticoagulation treatment for longer period than the elderly population and also because of a larger proportion of young population suffering from rheumatic heart disease. In our study, the patients with mechanical valves had greater postoperative LV systolic dysfunction which could be explained by a higher prevalence of regurgitant lesions, multivalvular involvement, and uncontrolled chronic atrial fibrillation in this group. Other disadvantage associated with mechanical valves is prosthetic valve obstruction due to poor compliance and suboptimal INR monitoring. Considering these issues, one of the largest retrospective observational studies in 2017 appealed for the liberalization of age from 60 to 45 years for the use of bioprosthetic valves for Indian patients.[10]

Paravalvular regurgitation is common in both mechanical and bioprosthetic heart valves (but symptomatic only in 1.5% of patients in the mechanical valve group). Although the complication rate was similar in the two groups for the initial 5 years, there was a steep fall in the bioprosthetic valve function later on associated with SVD which also corroborated with the other studies performed on bioprosthetic valves.

Overall survival rates for bioprosthetic valves for 1, 5, and 10 years were 99% and for mechanical valves were 98% at 5 years and 96% at 10 years in our study. Studies comparing surgical AVR using bioprosthetic and mechanical prosthetic valves report that 1-year survival is comparable. However, survival at 5 years is higher in mechanical aortic valves (95.5% vs. 82.6%). For the mitral valve, previous data confirm that the mechanical valve has higher 10-year survival compared to bioprosthetic heart valves.[11],[12],[13] Our data reports relatively lower survival for mechanical prosthetic heart valves. This could be explained on the basis of higher incidence of AF and preoperative LV systolic dysfunction in those patients selected for MVR surgery.[14],[15]


Our study was a retrospective observational study. It tried to identify potential valve-related events for each group; however, some of the valve-related events had low incidence. A larger study with prospective design is needed to highlight the differences/similarities between the two valve types, which is lacking in our study.

  Conclusion Top

In our study, we concluded that mechanical valves had a 96% survival rate at 10–15 years which was dependent on preoperative NYHA class, preoperative LV function, AF, and postoperative INR values. The occurrence of secondary outcomes was higher in patients with subtherapeutic INR values and mechanical mitral valve position. In contrast, bioprosthetic valves had 99% survival but with higher incidence of secondary outcomes, mainly in the form of SVD.

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Conflicts of interest

There are no conflicts of interest.

  References Top

Akins CW, Miller DC, Turina MI, Kouchoukos NT, Blackstone EH, Grunkemeier GL, et al. Guidelines for reporting mortality and morbidity after cardiac valve interventions. Ann Thorac Surg 2008;85:1490-5.  Back to cited text no. 1
Taylor KM. The Edinburgh heart valve study. Heart 2003;89:697-8.  Back to cited text no. 2
Hammermeister KE, Sethi GK, Henderson WG, Oprian C, Kim T, Rahimtoola S. A comparison of outcomes in men 11 years after heart-valve replacement with a mechanical valve or bioprosthesis. Veterans Affairs Cooperative Study on Valvular Heart Disease. N Engl J Med 1993;328:1289-96.  Back to cited text no. 3
Kaneko T, Aranki S, Javed Q, McGurk S, Shekar P, Davidson M, et al. Mechanical versus bioprosthetic mitral valve replacement in patients and lt; 65 years old. J Thorac Cardiovasc Surg 2014;147:117-26.  Back to cited text no. 4
Son J, Cho YH, Jeong DS, Sung K, Kim WS, Lee YT, et al. Mechanical versus tissue aortic prosthesis in sexagenarians: Comparison of hemodynamic and clinical outcomes. Korean J Thorac Cardiovasc Surg 2018;51:100-8.  Back to cited text no. 5
Jamieson WR, Burr LH, Tyers GF, Miyagishima RT, Janusz MT, Ling H, et al. Carpentier-Edwards supraannular porcine bioprosthesis: Clinical performance to twelve years. Ann Thorac Surg 1995;60:S235-40.  Back to cited text no. 6
David TE, Ivanov J, Armstrong S, Feindel CM, Cohen G. Late results of heart valve replacement with the Hancock II bioprosthesis. J Thorac Cardiovasc Surg 2001;121:268-77.  Back to cited text no. 7
Nitsche C, Kammerlander AA, Knechtelsdorfer K, Kraiger JA, Goliasch G, Dona C, et al. Determinants of bioprosthetic aortic valve degeneration. JACC Cardiovasc Imaging 2020;13:345-53.  Back to cited text no. 8
Puvimanasinghe JP, Steyerberg EW, Takkenberg JJ, Eijkemans MJ, van Herwerden LA, Bogers AJ, et al. Prognosis after aortic valve replacement with a bioprosthesis: Predictions based on meta-analysis and microsimulation. Circulation 2001;103:1535-41.  Back to cited text no. 9
Sharma D, Sisodia A, Devgarha S, Mathur RM. Midterm outcomes of mechanical versus bioprosthetic valve replacement in middle-aged patients: An Indian scenario. Heart India 2017;5:17-23.  Back to cited text no. 10
  [Full text]  
Šušak S, Velicki L, Popović D, Burazor I. Surgical valve replacement (Bioprosthetic vs. Mechanical). In: Aikawa E, editor. Calcific Aortic Valve Disease [Internet]. London: IntechOpen; 2013. Available from: https://www.intechopen.com/chapters/45028. [Last accessed on 2022 Nov 10].  Back to cited text no. 11
Huckaby LV, Sultan I, Gleason TG, Chen S, Thoma F, Navid F, et al. Outcomes of tissue versus mechanical aortic valve replacement in patients 50 to 70 years of age. J Card Surg 2020;35:2589-97.  Back to cited text no. 12
Cetinkaya A, Poggenpohl J, Bramlage K, Hein S, Doss M, Bramlage P, et al. Long-term outcome after mitral valve replacement using biological versus mechanical valves. J Cardiothorac Surg 2019;14:120.  Back to cited text no. 13
Acker MA, Gelijns AC, Kron IL. Surgery for severe ischemic mitral regurgitation. N Engl J Med 2014;370:1463.  Back to cited text no. 14
Shahian DM, He X, Jacobs JP, Kurlansky PA, Badhwar V, Cleveland JC Jr., et al. The society of thoracic surgeons composite measure of individual surgeon performance for adult cardiac surgery: A report of the society of thoracic surgeons quality measurement task force. Ann Thorac Surg 2015;100:1315-24.  Back to cited text no. 15


  [Figure 1], [Figure 2], [Figure 3], [Figure 4], [Figure 5]

  [Table 1], [Table 2]


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