European Journal of Cardiovascular Medicine

Cardiovascular disease (CVD) is a substantial and growing problem in most of the developing regions of the world [1]. Valvular heart disease remains frequent in industrialized countries since the decrease in frequency of rheumatic heart diseases has been accompanied by an increase in degenerative valve diseases [2]. But rheumatic valve disease still remains a major public health problem in developing countries [3]. Mitral valve disease (primarily regurgitation and/or stenosis) is among the most common valve-related conditions worldwide, representing almost one-third of all acquired left-sided valve pathologies [4], and rheumatic mitral valvular disease (MVD) is a common cause of cardiovascular morbidity and mortality in Bangladesh [5]. Most valvular disease is not curable medically and therefore requires surgical repair or replacement as definitive therapy.

The number of surgeries performed using less-invasive techniques has increased dramatically over the last two decades. While the minimally invasive approach has become the standard of care for many surgical procedures in the thoracic, abdominal and pelvic cavities, this shift was initially slower in cardiac surgery, since most heart operations are complex and require cardiopulmonary bypass along with high surgical precision. Advancements in diagnostic tools, development of specific cardiac endoscopic instruments, introduction of peripheral cardiopulmonary bypass circulatory systems, and novel surgical techniques have enabled cardiac surgeons to operate on the heart through very small incisions. Among the different areas of cardiac surgery, the minimally invasive approach has gained particular popularity in the field of mitral valve (MV) treatment [6].

Since the first description of minimally invasive mitral valve surgery (MIMVS) by Cohn and Cosgrove in the mid-1990s, various minimally invasive approaches have been reported, including parasternal, hemisternotomy, minithoracotomy, and totally endoscopic techniques [7]. Despite variation in surgical approaches, the shared goal of minimally invasive mitral valve surgery (MIMVS) is to provide a safe and effective option for mitral valve surgery (MVS) with the clinical benefits associated with a minimal access approach [8]. Minithoracotomy has been demonstrated to be a valid cost-effective and cost-saving strategy for valve surgery, being associated with reduced morbidity and mortality. Tangible benefits include less pain, faster postoperative recovery, and better cosmetic results, as well as decreased intensive care unit and total hospital length of stay, faster physical rehabilitation, and reduced overall hospital resource utilization [9]. As a result, the minithoracotomy approach has been increasingly used as a routine technique in many centers for mitral valve surgery [10].

Despite criticisms over the last decade, heart valve surgery through right anterior minithoracotomy (MT) has shown excellent short-term and long-term results, becoming a feasible and popular alternative to the sternotomy approach [10]. However, these reported benefits have often been tempered by concerns regarding the safety and durability of minimally invasive (MI) approaches. Potential disadvantages include decreased surgical exposure, difficulty in de-airing, longer cardiopulmonary bypass (CPB) time, longer aortic cross-clamp and overall operative times, inadequate mediastinal and pleural drainage, and increased risk of paravalvular leakage (PVL) [11]. Although there are currently no prospective randomized trials comparing minimally invasive (MI) to sternotomy (ST) approaches for mitral valve surgery (MVS), several single-institution studies have confirmed that many of the proposed benefits of MIMVS can be achieved without detrimental effects on morbidity, mortality, or long-term valve function [9].

Therefore, studies are ongoing worldwide, and it is important for surgeons to compare the early postoperative outcomes of mitral valve replacement performed via right mini-thoracotomy under direct vision versus conventional median sternotomy. Accordingly, the present study was undertaken to compare early postoperative outcomes of right mini-thoracotomy versus standard median sternotomy in patients undergoing isolated mitral valve replacement, to better understand the safety and effectiveness of these surgical approaches.

Objective

•             To compare early postoperative outcomes of right mini-thoracotomy versus standard median sternotomy in patients undergoing isolated mitral valve replacement.

This prospective observational comparative study was conducted at the Department of Cardiac Surgery, National Heart Foundation Hospital and Research Institute (NHFH & RI), Mirpur, Dhaka, Bangladesh, from July 2013 to June 2015. A total of 44 patients undergoing isolated mitral valve replacement (MVR) were included in the study and divided into two equal groups: Group 1 (n = 22) underwent MVR via right mini-thoracotomy, while Group 2 (n = 22) underwent MVR via standard median sternotomy, based on predefined inclusion and exclusion criteria to evaluate the early outcomes of the two surgical approaches. Inclusion Criteria i. Patients undergoing first-time isolated mitral valve replacement (MVR). Exclusion Criteria i. Patients undergoing redo mitral valve replacement (MVR) surgery. ii. Patients with left ventricular ejection fraction (LVEF) <30%. iii. Patients with MVR associated with other valvular lesions. iv. Patients requiring concomitant coronary artery bypass grafting (CABG) due to advanced coronary artery disease. v. Patients with associated congenital heart disease. Data were collected on demographic, clinical, echocardiographic (LVEF, LA diameter, PASP, atrial fibrillation), operative (operative time, cardiopulmonary bypass time, aortic cross-clamp time, incision length), and postoperative outcomes (ventilation time, ICU stay, hospital stay, pain score, complications, blood loss, transfusion requirement, and 30-day mortality), with echocardiographic follow-up performed at one month. Preoperative, intraoperative, postoperative, and follow-up data were recorded using a structured data collection sheet. Patients were assessed during hospital stay, at discharge, and at one-month follow-up with clinical evaluation and transthoracic echocardiography performed by a blinded cardiologist. All surgeries were performed by the same surgical team under standardized general anesthesia with routine monitoring, including ECG, arterial pressure, central venous pressure, pulse oximetry, and transesophageal echocardiography. In Group 1, MVR was performed via right mini-thoracotomy using femoral cannulation and cardiopulmonary bypass under minimally invasive exposure, while Group 2 underwent standard median sternotomy with central cannulation; in both groups, valve replacement was carried out under cardioplegic arrest using a standardized technique. Postoperatively, all patients were managed in the intensive care unit with standard protocols, including mechanical ventilation, hemodynamic monitoring, and stepwise transfer to the ward after stabilization. Data analysis was performed using SPSS version 16; continuous variables were expressed as mean ± standard deviation and compared using Student’s t-test, while categorical variables were analyzed using Chi-square or Fisher’s exact test, with p < 0.05 considered statistically significant. The study was approved by the Ethical Review Committee of NHFH & RI, and written informed consent was obtained from all participants, with confidentiality strictly maintained.

Table 1: Demographic and Preoperative Clinical Characteristics of the Study Population

The mean age of patients was 38.73 ± 11.97 years in the right mini-thoracotomy group and 38.27 ± 12.29 years in the median sternotomy group (p = 0.902). Male patients comprised 5 (22.7%) in the mini-thoracotomy group and 11 (50.0%) in the sternotomy group, while females accounted for 17 (77.3%) and 11 (50.0%), respectively. Most patients had mixed mitral valve disease (MS+MR), observed in 16 (72.8%) and 14 (63.6%) patients in the two groups, respectively, with no statistically significant differences between groups.

Table 2: Preoperative Echocardiographic and Clinical Cardiac Characteristics

The mean left ventricular ejection fraction was 57.36 ± 4.19% in the mini-thoracotomy group and 55.91 ± 7.59% in the sternotomy group (p = 0.436). Mean LA diameter was 53.55 ± 3.27 mm versus 53.86 ± 5.01 mm, respectively (p = 0.804), while PASP was 52.32 ± 10.73 mmHg and 51.00 ± 21.16 mmHg (p = 0.796). Atrial fibrillation was present in 4 (18.2%) and 3 (13.6%) patients, respectively, with no significant intergroup differences.

Table 3: Intraoperative Variables in Patients Undergoing Mitral Valve Replacement

Total operative time was significantly longer in the mini-thoracotomy group (229.95 ± 24.69 minutes) compared to the sternotomy group (207.68 ± 23.55 minutes, p = 0.004). Similarly, aortic cross-clamp time (77.68 ± 23.84 vs. 63.55 ± 12.15 minutes, p = 0.018) and cardiopulmonary bypass time (123.36 ± 27.58 vs. 103.09 ± 24.89 minutes, p = 0.014) were significantly increased in the mini-thoracotomy group. However, incision length was significantly smaller in this group (10.43 ± 0.77 cm vs. 22.41 ± 1.86 cm, p < 0.001).

Table 4: Early Postoperative Outcomes

The duration of mechanical ventilation was significantly shorter in the mini-thoracotomy group (11.64 ± 2.01 hours) compared to the sternotomy group (15.05 ± 4.19 hours, p = 0.001). Postoperative hospital stay was also reduced (6.91 ± 1.44 vs. 8.00 ± 1.90 days, p = 0.038), as was pain score (VAS 3.23 ± 0.43 vs. 5.50 ± 0.59, p < 0.001). ICU stay showed no significant difference between groups (39.36 ± 12.95 vs. 44.55 ± 12.97 hours, p = 0.192).

Postoperative complications were low and comparable between groups. Atrial fibrillation occurred in 1 (4.5%) patient in the mini-thoracotomy group and 2 (9.1%) in the sternotomy group (p = 1.000). Superficial wound infection was observed in 1 (4.5%) and 2 (9.1%) patients, respectively, while no cases of stroke, renal failure, or deep wound infection were recorded in either group. Thirty-day mortality occurred in 1 (4.5%) patient in the mini-thoracotomy group and none in the sternotomy group (p = 1.000).

Table 5: Postoperative Complications and 30-Day Mortality

Postoperative complications were low and comparable between groups. Atrial fibrillation occurred in 1 (4.5%) patient in the mini-thoracotomy group and 2 (9.1%) in the sternotomy group (p = 1.000). Superficial wound infection was observed in 1 (4.5%) and 2 (9.1%) patients, respectively, while no cases of stroke, renal failure, or deep wound infection were recorded in either group. Thirty-day mortality occurred in 1 (4.5%) patient in the mini-thoracotomy group and none in the sternotomy group (p = 1.000).

Table 6: Blood Loss and Transfusion-Related Outcomes

Patients in the mini-thoracotomy group had lower postoperative blood loss (207.50 ± 75.92 mL vs. 369.55 ± 220.81 mL, p = 0.003) and required less blood transfusion (400.00 ± 0.00 mL vs. 560.00 ± 206.55 mL, p = 0.037). Although a higher proportion of patients in the sternotomy group required transfusion (45.5% vs. 22.7%), this difference was not statistically significant (p = 0.112). No reoperation for bleeding was required in either group.

Table 7: Postoperative Echocardiographic Outcomes

Postoperative echocardiography demonstrated comparable cardiac function between groups. LVEF improved to 60.64 ± 4.03% in the mini-thoracotomy group and 58.05 ± 7.02% in the sternotomy group (p = 0.142). LA diameter reduced to 46.32 ± 2.77 mm and 46.36 ± 2.77 mm, respectively (p = 0.957), while PASP decreased to 37.05 ± 8.13 mmHg and 34.50 ± 7.81 mmHg (p = 0.295). No paravalvular leakage was observed in either group.

This study was conducted at the National Heart Foundation Hospital and Research Institute from July 2013 to June 2015. A total of 44 patients were enrolled and equally allocated into two groups: 22 patients underwent right mini-thoracotomy and 22 underwent conventional median sternotomy for isolated mitral valve replacement.

The mean age of patients was 38.73 ± 11.97 years in the right mini-thoracotomy group and 38.27 ± 12.29 years in the median sternotomy group, with no statistically significant difference between the groups (p = 0.902). In comparison, mean ages reported in a meta-analysis by Cheng et al.[12] were 54.0 ± 12.4 and 55.8 ± 12.6 years, while Dogan et al.[13] reported 60.1 ± 12.3 and 63.2 ± 13.6 years in similar groups. Thus, patients in the present study were considerably younger. This difference may be attributed to the higher prevalence of rheumatic heart disease in developing countries such as Bangladesh, where rheumatic mitral valvular disease typically manifests 10–30 years after the initial rheumatic insult.

Regarding sex distribution, males comprised 22.7% in the mini-thoracotomy group and 50.0% in the sternotomy group, while females accounted for 77.3% and 50.0%, respectively. The difference was not statistically significant (p = 0.060). Similar findings were reported by Ganie et al.[14] and Mishra et al.[15], where female predominance was also observed in patients undergoing mitral valve surgery.

In terms of preoperative diagnosis, most patients had mixed mitral valve disease (MS + MR), observed in 72.8% of the mini-thoracotomy group and 63.6% of the sternotomy group. Mitral regurgitation was present in 22.7% and 27.4% of patients, while mitral stenosis was observed in 4.5% and 9.0%, respectively. There were no statistically significant differences between the groups, indicating comparable baseline disease characteristics.

Operative variables demonstrated that total operative time was significantly longer in the mini-thoracotomy group (229.95 ± 24.69 minutes vs. 207.68 ± 23.55 minutes, p = 0.004). Similarly, aortic cross-clamp time (77.68 ± 23.84 vs. 63.55 ± 12.15 minutes, p = 0.018) and cardiopulmonary bypass time (123.36 ± 27.58 vs. 103.09 ± 24.89 minutes, p = 0.014) were significantly increased in the minimally invasive group. However, incision length was significantly smaller in the mini-thoracotomy group (10.43 ± 0.77 cm vs. 22.41 ± 1.86 cm, p < 0.001). These findings are consistent with Cheng et al.[12] and Modi et al.[16], who also reported longer operative and bypass times with minimally invasive approaches. Dogan et al.[13] similarly observed longer operative and cardiopulmonary bypass times in the minithoracotomy group, although differences in cross-clamp time were not always statistically significant. El-Fiky et al.[17] also reported prolonged cardiopulmonary bypass duration in minimally invasive mitral surgery.

Postoperative recovery parameters showed that duration of mechanical ventilation was significantly shorter in the mini-thoracotomy group (11.64 ± 2.01 hours vs. 15.05 ± 4.19 hours, p = 0.001). Postoperative hospital stay was also significantly reduced (6.91 ± 1.44 vs. 8.00 ± 1.90 days, p = 0.038), as was pain score (VAS 3.23 ± 0.43 vs. 5.50 ± 0.59, p < 0.001). However, ICU stay did not differ significantly between groups (39.36 ± 12.95 vs. 44.55 ± 12.97 hours, p = 0.192). Cheng et al.[12] reported shorter ventilation time and reduced ICU and hospital stay in minimally invasive surgery, although pain reduction was not significantly different. In contrast, Ritwick et al.[18] identified reduced postoperative pain and faster recovery as the most consistent benefit of minimally invasive approaches. Similarly, Luca et al.[8] in a systematic review concluded that thoracotomy approaches are associated with less pain, discomfort, and reduced analgesic requirements compared to median sternotomy. Ward et al.[19] also reported reduced ICU and hospital stay in the minimally invasive group.

Blood loss-related outcomes demonstrated significantly lower postoperative blood loss in the mini-thoracotomy group (207.50 ± 75.92 mL vs. 369.55 ± 220.81 mL, p = 0.003). The mean volume of blood transfused was also significantly lower in this group (400.00 ± 0.00 mL vs. 560.00 ± 206.55 mL, p = 0.037). Although a higher proportion of patients required transfusion in the sternotomy group (45.5% vs. 22.7%), this difference was not statistically significant (p = 0.112). No reoperation for bleeding was required in either group. These findings are consistent with Cheng et al.[12], Modi et al.[16], and El-Fiky et al.[17], all of whom reported reduced bleeding and transfusion requirements with minimally invasive mitral valve surgery. Ward et al.[19] further supported that minimally invasive approaches are associated with lower bleeding risk, while Mishra et al.[15] reported reduced chest tube drainage and transfusion requirements in minimally invasive procedures.

Thirty-day mortality was low, with one death (4.5%) in the mini-thoracotomy group and none in the sternotomy group, resulting in an overall mortality of 2.27%. The difference was not statistically significant (p = 1.000). Cheng et al.[12] also reported no significant difference in mortality between minimally invasive and conventional mitral valve surgery. Similarly, Grossi et al.[20] demonstrated comparable hospital mortality between port-access and median sternotomy approaches.

Postoperative complications, including stroke and renal failure, were not observed in either group. Atrial fibrillation occurred in 4.5% of patients in the mini-thoracotomy group and 9.1% in the sternotomy group, with no statistically significant difference. Similar findings were reported by Modi et al.[16] and Ward et al.[19], who found no significant difference in postoperative atrial fibrillation between surgical approaches. However, Cheng et al.[12] reported a reduced incidence of atrial fibrillation in minimally invasive surgery, potentially due to reduced surgical trauma and inflammatory response.

Wound infection rates were low and comparable between groups, with superficial wound infection occurring in 4.5% and 9.1% of patients, respectively, and no deep wound infections observed. Luca et al.[8] reported reduced wound infection rates in thoracotomy approaches compared to sternotomy, while Ward et al.[19] also observed no deep sternal wound infections in minimally invasive groups.

Echocardiographic outcomes demonstrated significant improvement in both groups. The mean LVEF increased from 57.36 ± 4.19% preoperatively to 60.64 ± 4.03% postoperatively in the mini-thoracotomy group, and from 55.91 ± 7.59% to 58.05 ± 7.02% in the sternotomy group. LA diameter decreased from 53.55 ± 3.27 mm to 46.32 ± 2.77 mm and from 53.86 ± 5.01 mm to 46.36 ± 2.77 mm, respectively. Similarly, PASP decreased from 52.32 ± 10.73 mmHg to 37.05 ± 8.13 mmHg and from 51.00 ± 21.16 mmHg to 34.50 ± 7.81 mmHg. No paravalvular leakage was observed in either group. Overall, both surgical approaches demonstrated satisfactory and comparable echocardiographic outcomes, with improved ventricular function and reduced pulmonary pressures postoperatively.

Limitations of the study

There are some limitations in this study, which are mentioned below:

•           This was a single-center study.

•           The sample size was relatively small.

•           A purposive non-random sampling method was used.

•           Follow-up was limited to one month, with no long-term outcome data.

•             Postoperative quality of life measures, including patient satisfaction, return to work, level of discomfort, and ability to perform daily activities, were not assessed.

Based on the findings of this study, we conclude that mitral valve replacement can be safely performed via right mini-thoracotomy without compromising patient safety. The right mini-thoracotomy approach demonstrated several advantages, particularly a reduced incision length, shorter duration of endotracheal intubation, lower postoperative blood loss and transfusion requirement, less postoperative pain, and shorter hospital stay. Patients in the right mini-thoracotomy group also had smaller scars as expected, which contributed to improved overall patient satisfaction.

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