Are small-sized mechanical valves adequate for patients with small aortic roots?

Abstract

Aim

Concerns have been raised over patient outcomes following implantation of small aortic valves (size: 19 and 17 mm). However, in patients with a smaller body surface area, these valves may be adequate. The aim of th study was to assess the hemodynamic and functional performance of these valves and their impact on clinical outcomes in patients with a small aortic root.

Material and methods

This was a prospective observational study that included all consecutive patients undergoing aortic valve replacement (AVR) with a small-sized aortic valve over a 3-year period. Patients were followed up at 1 week, 6 weeks, and 1 year. Functional and clinical evaluation along with echocardiography was carried out for hemodynamic assessment. In-hospital mortality and hemodynamic outcomes at 1-year follow-up were recorded.

Results

Isolated AVR with a size 17 mm valve was carried out in 15 (25%) and with a 19 mm valve in 45 (75%) patients. The mean annular size was 19.12 ± 2.03 mm. The mean indexed effective orifice area was 1.08 ± 0.16 cm²/m². Satisfactory decrease in peak and mean trans-prosthetic gradient were evident (peak gradient preoperatively was 92.15 ± 26.2 mmHg, and 25.68 ± 12.28 mmHg at 1 year, mean gradient was 55.31 ± 17.41 mmHg preoperatively and 13.71 ± 7.39 mmHg at 1 year). The functional status of patients also showed significant improvement post AVR. Left ventricular ejection fraction pre-operatively was 59.67% ± 10.38% and 59.57% ± 7.98% at 1-week, 59.15% ± 8.17% at 6 weeks, and 59.59% ± 7.48% at 1 year.

Conclusion

When confronted with a small aortic root, AVR with a small-sized prosthesis provides a satisfactory hemodynamic and functional outcome. In patients with small body surface area, implantation of a small-sized valve is a viable option.

Keywords

Patient prosthesis mismatch small aortic root aortic valve replacement

Introduction

Aortic valve (AV) prostheses have played an important part in the management of patients with aortic valvular heart disease. The goal of the surgery is to replace the diseased valve (stenotic or regurgitant) with a competent, non-stenotic prosthesis that allows resolution of patient’s symptoms and normalisation of hemodynamics.¹

AV replacement (AVR) thus results in a low gradient post-operatively and facilitates left ventricular (LV) regression and functional improvement. For this, it is important to implant an adequately sized valve which produces hemodynamics similar to the normal native valve. The adequacy of the valve is dependent on the indexed effective orifice area (iEOA) which is derived from the effective orifice area (EOA) of the implanted valve and the body surface area (BSA) of the patient. Implanting a valve that is small for the patient leads to patient prosthesis mismatch (PPM).

Preventing PPM is a challenge when confronted with a small aortic root. The two most common operative strategies, for patients with a small aortic root, involve root enlargement followed by replacement with a larger valve or implantation of a smaller-sized valve (19 or 17 mm). The concern with root enlargement is that it is a technically challenging procedure and carries a higher operative risk than a simple AVR.² The operative mortality after root enlargement is twice that of standard AVR. Operative morbidity because of a longer cardiopulmonary bypass and cross-clamp time has also been reported.³ On the other hand, implantation of a small AV may lead to persistent high gradient, poor LV wall regression and PPM which has an adverse effect on patient outcomes.

While there are reports suggesting that implantation of a small AV prosthesis, leads to adverse short- and long-term outcomes, several recent studies have indicated an acceptable clinical outcome in patients undergoing AVRs with small AVs. Moreover, most of the studies showing PPM with small-sized AVs were carried out in the Western population and it is likely that in the Asian population, due to a relatively smaller body size, implantation of a size 19 mm or 17 mm mechanical prosthesis may not lead to significant PPM and the resultant adverse effects. The hypothesis of our study was that implantation of a small-sized (19 or 17 mm) mechanical prosthesis leads to satisfactory hemodynamic and functional outcomes in patients with smaller BSA.

Material and methods

Study design

This was a prospective observational single-group study carried out at a tertiary care centre that included all patients undergoing isolated AVR with 19 and 17 mm mechanical prosthetic valves without an aortic root enlargement. The aim of the study was to assess the hemodynamic performance of 19 and 17 mm supra-annular mechanical AV in patients undergoing isolated AV replacement. The other objectives included assessment of patient prosthetic mismatch, its impact on clinical outcomes and changes in functional status of the study population during follow-up.

Ethics

The protocol along with a patient information sheet and informed consent form was reviewed and approved by the institutional ethical committee of the institute (Ref: NHRTIICS-EC/AP/2016) on 1 August 2016.

Sample size calculation

The sample size was determined using the formula based on previously published data.⁴ Based on this, 58 patients were required in the study, and we aimed to recruit 60 patients to account for dropouts.

Inclusion criteria

All consecutive patients undergoing AVR with a 19 or 17 mm valve, above the age of 18 and who were willing to participate and sign the informed consent document were included in the study.

Exclusion criteria

We excluded patients who were undergoing redo AVR or concomitant procedures or had evidence of active endocarditis or required emergency operation.

Study outcomes and follow-up

The primary outcome was the hemodynamic performance of the valve. The secondary outcome was functional status of the patients assessed by the New York Heart Association Class (NYHA). At the time of discharge, an electrocardiogram and two-dimensional (2D) echocardiogram were carried out on all patients and the findings recorded. Postoperatively, evaluation was performed on all patients at 1 week, 6 weeks, and 1 year. Functional status and echocardiographic evaluations were conducted at each visit.

Procedural details

Anaesthetic technique

A standard anaesthetic technique was used throughout. Short-acting opioids and volatile anaesthesia were used for induction and maintenance. All patients who were hemodynamically stable with an uneventful intraoperative course were eligible for an early extubation. Patients were extubated as soon as they met the following criteria: hemodynamic stability, no excessive bleeding (<80 ml/h), normothermia, and consciousness with adjunctive pain control.

Perfusion technique

Myocardial protection was achieved using systemic cooling to 28°C, and cardioplegic arrest. Predominantly Del Nido blood cardioplegia was used and in some patients, St Thomas’s type 2 blood cardioplegia solution given at 4°C was used.

Surgical technique

The technique of AVR was broadly similar among surgeons. Ventriculo-arterial non-everting interrupted mattress sutures using 2-0 nonabsorbable, braided polyethylene terephthalate sutures were used to suture the prosthesis-sewing ring to the annulus. Buttressed sutures using polytetrafluoroethylene pledgets were used in patients where significant annular decalcification was required and there was concern over the annular integrity. None of the patients in this series required septal myomectomy or aortic root enlargement. However, in few cases, a pericardial patch was required to close the aortotomy.

Anti-coagulation

Oral Warfarin Sodium or Acenocoumarol (based on individual preference) were started on 1st postoperative day and doses titrated to maintain the international normalised ratio at 2.5 to 3.5.

Definitions

Standard M mode 2D Echocardiography was carried out and standard views and dimensions were obtained according to the American Society of Echocardiographic Criteria. The maximal instantaneous pressure gradient across the prostheses was estimated by the modified Bernoulli equation; the mean pressure gradient was derived by planimetry of the Doppler envelope. In-hospital mortality was defined as mortality during the index operation.

BSA was calculated using the Dubois formula for calculation (BSA = 0.007184 × height (0.725) × weight (0.425)). Indexed EOA was calculated by dividing the EOA of the valve prosthesis by the patient’s BSA. PPM was defined as mild if iEOA was >0.85 cm²/m², moderate if <0.85 cm²/m² but >0.65 cm²/m² and severe if it was <0.65 cm²/m².⁵ A neurologic event included any new, temporary [transient ischemic attack (TIA), confusion], or permanent (stroke) focal or global neurologic deficit. LV ejection fraction (LVEF) was graded along reported guidelines (normal >50%, mild impairment 40%–49%, moderate impairment 30%–39%, severe impairment <30%).⁶ Renal failure was defined using the risk, injury, failure, loss of kidney function and end-stage kidney disease classification. Vasoactive-inotropic score (VIS) was used to quantify the inotropic support. The assessment was carried out 24 h post-op in all patients and was calculated as follows: VIS = dopamine dose (mcg/kg/min) + dobutamine dose (mcg/kg/min) + 100 × epinephrine dose (mcg/kg/min) + 10 × milrinone dose (mcg/kg/min) + 10,000 × vasopressin dose (units/kg/min) + 100 × norepinephrine dose (mcg/kg/min).

Statistical methods

All continuous variables were expressed as mean ± standard deviation or median (1st quartile, 3rd quartile) as appropriate. Qualitative variables were expressed as numbers and percentages. A comparison between two groups was done by independent sample t-test or Mann–Whitney test as appropriate for continuous variables and the chi-square test or Fisher’s exact test for categorical variables. A p-value <0.05 was considered statistically significant. Statistical software SPSS 21.0 was used for analysis.

Results

The study period ranged from 2017 to 2020 and included patients who underwent isolated AVR with either a 17 mm or 19 mm mechanical aortic prosthetic valve.

Demographics

The study included 60 patients of which 26 (43.33%) were females with an overall mean age of 46.92 ± 13.38. The most common presenting symptoms in the study population was dyspnoea which was seen in 59 (98.3%) cases and angina in 51 (85%) cases. The demographic data of the study patients is detailed in Table 1. Fifty (83.3%) of the patients had EuroSCORE II between 2 and 5. The median EuroSCORE II was 1.13 (range 0.41–8.07). The mean BSA in our study was 1.52 ± 0.14 m² with the largest BSA being 1.83 m². Pre-operative peak trans prosthetic gradient was 92.15 ± 26.2 mmHg. There were 10(17%) patients who had an impaired LV function. Other pre-operative echocardiographic data is detailed in Table 1. The aetiology of AV disease was predominantly calcific degeneration seen in 30 (50%) cases. Other aetiology included bicuspid AVs, rheumatic valves and mixed valvular disease. Five patients (8%) had aortic regurgitation with aortic stenosis and 55 (92%) had predominantly stenotic AVs.

Table 1.

Baseline characteristics.

Age	46.92 ± 13.38
BMI (kg/m²⁾	23.17 ± 4.78
BSA (m²)	1.53 ± 0.14
Gender
Male	34 (56.67%)
Female	26 (43.33%)
Pre-op Atrial fibrillation or any other arrhythmia	4 (6.67%)
Angina (CCS grading)
CCS 0	9 (15.00%)
CCS 1	10 (16.67%)
CCS 2	30 (50.00%)
CCS 3	11 (18.33%)
Palpitation	20 (33.33%)
NYHA
NYHA I	3 (5.00%)
NYHA II	27 (45.00%)
NYHA III	27 (45.00%)
NYHA IV	3 (5.00%)
Hypertension	19 (31.67%)
Diabetes mellitus	13 (21.67%)
COPD/asthma	2 (3.33%)
Thyroid abnormality	4 (6.67%)
Renal Impairment	1 (1.67%)
Stroke	7 (11.67%)
Smoking	7 (11.67%)
Euroscore: median (IQR 1–IQR-3)	1.13 (0.68–1.43)
0–2	7 (11.67%)
2–5	50 (83.33%)
>5	3 (5%)
LV function (ejection fraction %)	59.67 ± 10.38
>50% (no Impairment)	50 (83.3%)
40%–49% (mild Impairment)	4 (6.7%)
30%–39% (moderate Impairment)	3 (5%)
<30% (severe Impairment)	3 (5%)
Aortic annulus (mm)	19.12 ± 2.03
Peak gradient (mmHg)	92.15 ± 26.2
Mean gradient (mmHg)	55.31 ± 17.41

BMI: body mass index; BSA: body surface area; CCS: Canadian Cardio-Vascular Society; NYHA: New York Heart Association; COPD: Chronic obstructive pulmonary disease; IQR: interquartile range; LV: left ventricular.

Operative data

Del Nido’s blood cardioplegia was used in 55 (91.6%) of the patients and St. Thomas’s type 2 blood cardioplegic solution was used in 5 (8.4%). The mean cross-clamp time was 111.82 ± 36.01 min (median: 117). The mean cardiopulmonary bypass time was 146.45 ± 40.37 min (median: 150). The valves used included St Jude Medical Regent™ in most cases [52 (86.7%)]. LivaNova Bicarbon Slimline was used in 8 (13.3%) of the patients. A 17 mm sized valve was implanted in 15 (25%) patients (13 patients with St Jude Medical Regent™ and 2 patients with LivaNova Bicarbon Slimline) whereas in 45 (75%) patients a 19 mm mechanical valve prosthesis (39 patients with St Jude Medical Regent™ and 6 patients with LivaNova Bicarbon Slimline) was used.

In-Hospital outcomes

There were no in-hospital deaths. Significant inotropic support was required only in 2 patients with most of the patients (47, 78.3%) needing low inotropic support and 11(18.3%) needing moderate Inotropic support. Median intensive therapy unit (ITU) stay was 2.93 days (interquartile range (IQR) 1.96–4.78). Total hospital stay was a median of 12 days (IQR 10–14.75 days). The post-operative length of stay was much shorter at a median of 7 days (IQR 6–9 days). Two (3.33%) patients got re-intubated, and the median intubation time was 12.48 h. Blood loss was minimal with a mean 24-h blood loss of only 260 ml.

The VIS score was low in majority (47, 78.3%) of the patients, moderate in 11 (18.3%) and significant in a small proportion (2,3.3%) of the study population. In valve size 17, 12 (80%) patients required low inotropic support, 2 (13.3%) had moderate and 1 (6.6%) had significant support. In patients where a valve size 19 implantation was carried out, 35 (77.7%) required low inotropic support, 9 (20%) required moderate inotropic support, and only 1 (2.2%) patient required significant inotropic support. There were no differences between the valve sizes with respect to the need for inotropic support (p = 0.62).

Two patients had pulseless ventricular tachycardia for which they received cardiopulmonary resuscitation and were successfully revived. Chest was left open in one patient for 48 h due to hemodynamic instability in the immediate postoperative period. Four patients (6.67%) required permanent pacemaker implantation. Other postoperative complications are detailed in Table 2. There was no loss to follow-up at 1 year. One patient died during the 1-year follow-up due to chronic kidney disease.

Table 2.

Post-operative outcomes.

Blood loss (24 h post-op)(ml)	260.42 ± 162.3173
Blood loss (total) (ml)	Mean 445.25 ± 257.75
Total Intubation time (hours)	12.72 ± 5.54
Total ITU stay (days)	3.72 ± 2.26
Total post-op stay (days)	7.8 ± 2.69
Total hospital stay (days)	12.9 ± 4.61
Re-intubation	2 (3.33%)
Blood transfusion
PRBC	2.58 ± 1.41
Platelet	0.23
FFP	1.55
Respiratory complications	4 (6.67%)
Renal Impairment	1 (1.67%)
Neurological impairment (TIA)	1 (1.67%)
Sternal wound infection	4 (6.67%)
Need of re-transfer to ITU	0 (0.00%)
Any adverse course during the course in the hospital	5 (8.33%)
Heart block	1 (1.67%)
Need for permanent pacemaker	4 (6.67%)

PRBC: packed red blood cell; TIA: transient ischemic attack; FFP: fresh frozen plasma; ITU: intensive therapy unit.

Hemodynamic outcome data

Significant hemodynamic improvement was observed in terms of peak transprosthetic gradient (TPG), which decreased from 92.15 ± 26.2 mmHg in the preoperative period to 26.10 ± 9.58 mmHg at the time of discharge. The peak gradient further decreased to 25.80 ± 8.55 mmHg at 1 week, 24.45 ± 8.39 mmHg at 6 weeks and was found to be 25.68 ± 12.28 mmHg at 1-year follow-up (Table 3 and Figure 1). In a similar fashion, the mean TPG decreased significantly from 55.31 ± 17.41 mmHg preoperatively to 13.65 ± 5.64 mmHg at the time of discharge, 13.82 ± 5.21 mmHg at 1 week, 12.55 ± 4.7 mmHg at 6 weeks and finally 13.71 ± 7.30 mmHg at 1-year follow-up (Table 3 and Figure 1). The mean LVEF was 59.67% pre-operatively. The LVEF was maintained throughout the follow-up period and remained satisfactory at 1-year follow-up (59.59% ± 7.48%) (Table 3 and Figure 1).

Table 3.

Echocardiographic evaluation of valve function.

	Pre-op	At discharge	At 1 week	At 6weeks	At 1 year
Peak gradient (mmHg)
Mean ± SD	92.15 ± 26.2	26.10 ± 9.68	25.80 ± 8.55	24.45 ± 8.39	25.68 ± 12.28
Median	91.00	25.50	26.00	22.50	22.00
Mean gradient (mmHg)
Mean ± SD	55.31 ± 17.41	13.65 ± 5.46	13.82 ± 5.21	12.55 ± 4.7	13.71 ± 7.39
Median	54.00	13.00	14.00	12.00	12.00
LV function (%)
Mean ± SD	59.67 ± 10.38	58.93 ± 9.16	59.57 ± 7.98	59.15 ± 8.17	59.59 ± 7.48
Median	62	62	62	61	60

SD; standard deviation; LV: left ventricular.

Functional outcome data

There was a significant improvement in the NYHA class. Three patients who were in NYHA class IV pre-operatively at the time of discharge improved to NYHA I during follow-up. Of the 27 patients in class III, 25 moved to class I and 2 to class II. During the course of follow-up at the end of 1 year, 58 (98.3%) of the patients alive (n = 59) were in either NYHA I or NYHA II. Only 1 patient during the course of follow up downgraded to NYHA III (Figure 2).

Comparison between 17 and 19 mm valves

The overall iEOA was 1.08 cm²/m². Size 19 mm valves provided a significantly higher iEOA compared to size 17 mm valves (1.11 ± 0.15 cm²/m² vs. 0.98 ± 0.16 cm²/m²; p = 0.001). However, despite a lower iEOA, there was no incidence of PPM owing to the lower BSA seen in our study population. The largest BSA in our study was 1.83 who received a size 17 mm valve and the iEOA in this patient was 0.89. Both the peak and the mean gradients remained comparable between 17 mm and 19 mm valves at all-time points of comparison (Table 4).

Table 4.

Echocardiographic comparison between size 17 and 19 mm valves.

Time	17 mm	19 mm	p-value
Pre-op peak gradient	94.33 ± 21.22	91.41 ± 27.88	0.85
At discharge	26.07 ± 9.82	26.11 ± 9.74	0.82
At 1 week	25.87 ± 7.34	25.78 ± 8.99	0.72
At 6 weeks	23.80 ± 7.45	24.67 ± 8.75	0.93
At 1 year	26.6 ± 18.56	25.36 ± 9.34	0.51
Pre-op mean gradient	52.67 ± 13.95	56.2 ± 18.5	0.41
At discharge	14.6 ± 6.5	13.33 ± 5.11	0.4
At 1 week	14.87 ± 5.14	13.47 ± 5.24	0.21
At 6 weeks	12.93 ± 5.05	12.42 ± 4.63	0.74
At 1 year	14.73 ± 11.43	13.36 ± 5.53	0.87
Pre-op LV function	63.6 ± 5.95	58.36 ± 11.25	0.25
At discharge	62.27 ± 6.06	57.82 ± 9.79	0.44
At 1 week	62.07 ± 5.19	58.73 ± 8.6	0.47
At 6 weeks	61.67 ± 6.92	58.31 ± 8.45	0.08
At 1 year	61.13 ± 8.81	59.07 ± 7	0.24

LV: left ventricular.

The LVEF in the 17 mm valve group was higher pre-operatively at 63.6 ± 5.95 mmHg compared to 19 mm valves (58.36 ± 11.25) but not significantly so (p = 0.25). The mean preoperative LVEF was 5.3% higher in the 17 mm valve group. However, at the end of 1 year, this difference was reduced to 2.1% (Table 4). Even though there was no significant difference observed between the 2 groups at 1 year the trend line for the 17 mm valves suggested a slight decrease in LVEF but the trend line for the size 19 mm valve was almost horizontal (Figure 3). There was no significant difference between the NYHA class of the patients depending on the valve size at any stage of the follow-up. It was seen that NYHA at different time periods including pre-op was not significantly different in the two groups (17 mm and 19 mm) (Table 5).

Table 5.

Comparison of New York Heart Association (NYHA) class between 17 and 19 mm valves.

Timing	17 mm	19 mm	P-value
Pre-op
NYHA I	1	2	0.32
NYHA II	1	22
NYHA III	5	19
NYHA IV	8	2
Discharge
NYHA I	15	42	0.57
NYHA II	0	3	0.57
1 week
NYHA I	15	43	1
NYHA II	0	2	1
6 months
NYHA I	15	42	0.57
NYHA II	0	3	0.57
1 year
NYHA I	12	38	0.225
NYHA II	2	6
NYHA III	1

Discussion

The main findings of our study were that in a population with smaller BSA, small-sized mechanical AVs (17 and 19 mm) provide satisfactory hemodynamics and do not lead to PPM. The LVEF at 1-year follow-up was maintained and there was a significant functional improvement as evidenced by the improving NYHA class. The peak and mean trans-prosthetic gradient in these patients at 1 year remained acceptable. In-hospital (100%) and 1-year survival (98.3%) were satisfactory. While the hemodynamic and functional improvement after an appropriately sized 19 mm and 17 mm valve was similar there was a non-significant benefit with a 19 mm valve in maintaining the LVEF.

BSA has been shown to be inversely correlated with operative mortality.⁷ PPM is also an independent predictor for short-term mortality and has a significant adverse impact, especially in patients with impaired LV function.⁸ Apart from reduced LV mass regression and decreased coronary flow reserve, severe PPM has also been associated with poor short- and long-term survival as well as an increase in cardiac and all-cause mortality.^8–10 However, since PPM is defined as iEOA (EOA/BSA), it is therefore not just the size of the valve but also the BSA that contributes to PPM.⁵ Thus, the same size valve may cause significant PPM and poor hemodynamics in one patient, but can provide satisfactory results in another. Thus, BSA forms the basis of the rationale for using small-sized valves in a population with smaller BSA without any serious adverse outcome. Most of the data available in the literature that discusses PPM is from the Western population where the BSA is as high as 1.9 m².^4,11 There is limited data available that is specific to the Asian population with a smaller BSA. The mean BSA in our study was 1.53 ± 0.14 m². Other studies carried out in Asian patients provide an even lower BSA of 1.29 m² among patients undergoing AVR¹². Even using 1.7 m² as the cut-off, satisfactory outcomes have been reported with small AVs in patients with regard to early mortality, hemodynamic performance on dobutamine stress testing and long-term outcomes.^13–15

In our study, we achieved a mean iEOA of 1.11 ± 0.15 cm²/m² in patients with size 19 mm valves and 0.98 cm²/m² in patients in whom a 17 mm valve was implanted. Thus, despite using a small-sized valve, no PPM was observed in our study. It also must be stressed that it is only severe PPM that has been proven to be associated with adverse postoperative outcomes. There is very little evidence in the literature to support the hypothesis that mild to moderate PPM leads to adverse outcomes. Evidence from a meta-analysis suggests that while severe PPM led to reduced survival, moderate PPM increased mortality only in the presence of poor LV function.⁸

The main consequence of insertion of a small-size mechanical prosthesis is thought to be generation of an abnormally high TPG across the AV.¹⁶ In our study, all patients received small-sized valves, with 15 patients receiving size 17 mm valves. Despite this, satisfactory TPG and hemodynamics was observed at follow-up in all cases. The peak TPG in our study was 26.6 ± 18.56 with a mean TPG of 14.73 ± 11.43 at 1 year. A similar study that specifically examined the performance of size 17 mm valves in patients with a much higher mean BSA of 1.68 m² also reported peak and mean TPG of 29 ± 6.8 and 17.5 ± 4.5 mmHg, respectively, at 6 months with satisfactory early and mid-term outcomes.²

Besides, improvement in echocardiographic measurements, there was significant functional improvement among the study patients as evidenced by an improvement in the NYHA class. Significant functional and hemodynamic improvement was seen in our patient population at 1-year follow-up. While the majority of the patients had improvement from NYHA class III to class I, some patients improved from class IV to class I. Similar functional improvement was seen in other studies where size 17 and 19 mm valves were implanted.^17,18 There were also no readmissions in our study with valve-related complications in any of the patients.

There is very limited information in the literature on comparisons of outcomes between 17 mm and 19 mm valves. Our study demonstrated that there was virtually no difference in the hemodynamic (mean or peak gradients) or the functional outcome (NYHA class) between these valves. This further illustrates the fact that it is not the size of the valve per se that determines the outcome but the BSA. Our study, however, did show a trend towards improvement of LVEF with size 19 mm valves. This difference though was not statistically significant or clinically relevant.

The other options that exist to deal with small aortic roots have several important issues too. Root enlargement procedures are technically challenging, and a long learning curve is required to master them. While no patients in our study experienced severe PPM, the adverse outcome of PPM when it occurs, cannot be underestimated. PPM has been shown to have a significant impact on patients with LVEF <40% and those below the age of 60 years. Both severe and moderate PPM impact long-term survival.⁹ Even moderate PPM leads to reduced LV mass regression as well as significantly reduced coronary flow reserve.¹⁰ Hence, PPM must be avoided, and aortic root enlargement is an important component in the armamentarium of the cardiac surgeon. A similar study carried out in Japanese patients with small aortic roots has shown that aortic root enlargement has not been associated with increased in-hospital and 30-day mortality or other adverse outcomes.¹⁹ Stentless valves, Ross procedures and Trans Catheter AVR (TAVR) are other options which may be used to deal with smaller aortic roots. However, there are several issues with each of these modalities. Stentless valves mimic the anatomy of the native AV but issues related to the complexity of surgical implantation and other technical difficulties remain.²⁰ Homograft replacements (Ross procedure) require specialised training and experience and are used selectively at present. TAVR is another alternative and provides superior valve hemodynamics with less incidence of PPM but is mainly indicated in elderly patients and patients who are at high surgical risk. Cost is another factor especially in developing countries.

Limitations: This is a single-centre non-randomized study where follow-up was limited to only 1 year. We concentrated on the occurrence of PPM and its clinical impact. Our study did not report data on echocardiographic features such as LV regression, LV size and effect of exercise testing which could have provided further insight. Even though the study was adequately powered to test our hypothesis, a larger number of patients across several institutions would be required to generate results that would be more generalisable. Apart from a small number of patients, a follow-up limited to only one year is an important limitation. Considering that the patients in our series were relatively younger a careful follow-up would be necessary to monitor for hemodynamic and functional deterioration. Management of these patients would be especially challenging as TAVR will not be an option in this cohort of patients. Besides, the inclusion–exclusion criteria adopted in this study led to relatively low-risk patients (median 1.13) being included in the cohort and extrapolation to higher-risk patients should be carried out with caution.

Conclusions: Implantation of size 19 or 17 mechanical AV leads to satisfactory clinical and haemodynamic outcomes in patients with smaller BSA. LV ejection fraction was also preserved during the course of follow-up. Incidence of PPM in our study population was not observed due to small BSA in the study population. Thus, in patients with narrow aortic roots and small BSA, implantation of a small-sized AV is one of the acceptable surgical strategies.

Footnotes

Declaration of conflicting interests

The authors declared no potential conflicts of interest with respect to the research, authorship, and/or publication of this article.

Funding

The authors received no financial support for the research, authorship, and/or publication of this article

Ethical approval

Not applicable.

Informed consent

Not applicable.

ORCID iD

Pradeep Narayan

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