Impact of patient-prosthesis mismatch and aortic valve design on coronary flow reserve after aortic valve replacement

Effect of aortic valve replacement on myocardial perfusion and exercise capacity in patients with severe aortic stenosis

Aortic valve replacement (AVR) leads to reverse cardiac remodeling in patients with aortic stenosis (AS). The aim of this secondary pooled analysis was to assess the degree and determinants of changes in myocardial perfusion post AVR, and its link with exercise capacity, in patients with severe AS. A total of 68 patients underwent same-day echocardiography and cardiac magnetic resonance imaging with adenosine stress pre and 6-12 months post-AVR. Of these, 50 had matched perfusion data available (age 67 ± 8 years, 86% male, aortic valve peak velocity 4.38 ± 0.63 m/s, aortic valve area index 0.45 ± 0.13cm2/m2). A subgroup of 34 patients underwent a symptom-limited cardiopulmonary exercise test (CPET) to assess maximal exercise capacity (peak VO2). Baseline and post-AVR parameters were compared and linear regression was used to determine associations between baseline variables and change in myocardial perfusion and exercise capacity. Following AVR, stress myocardial blood flow (MBF) increased from 1.56 ± 0.52 mL/min/g to 1.80 ± 0.62 mL/min/g (p < 0.001), with a corresponding 15% increase in myocardial perfusion reserve (MPR) (2.04 ± 0.57 to 2.34 ± 0.68; p = 0.004). Increasing severity of AS, presence of late gadolinium enhancement, lower baseline stress MBF and MPR were associated with a greater improvement in MPR post-AVR. On multivariable analysis low baseline MPR was independently associated with increased MPR post-AVR. There was no significant change in peak VO2 post-AVR, but a significant increase in exercise duration. Change in MPR was associated with change in peak VO2 post AVR (r = 0.346, p = 0.045). Those with the most impaired stress MBF and MPR at baseline demonstrate the greatest improvements in these parameters following AVR and the magnitude of change in MPR correlated with improvement in peak VO2, the gold standard measure of aerobic exercise capacity.

Myocardial Blood Flow Reserve, Microvascular Coronary Health, and Myocardial Remodeling in Patients With Aortic Stenosis

BACKGROUND

Coronary microvascular function and hemodynamics may play a role in coronary circulation and myocardial remodeling in patients with aortic stenosis (AS). We aimed to evaluate the relationship between myocardial blood flow and myocardial function in patients with AS, no AS, and aortic valve sclerosis.

METHODS AND RESULTS

We included consecutive patients who had resting transthoracic echocardiography and clinically indicated positron emission tomography myocardial perfusion imaging to capture their left ventricular ejection fraction, global longitudinal strain (GLS), and myocardial flow reserve (MFR). The primary outcome was major adverse cardiovascular event (all-cause mortality, myocardial infarction, or late revascularization). There were 2778 patients (208 with aortic sclerosis, 39 with prosthetic aortic valve, 2406 with no AS, and 54, 49, and 22 with mild, moderate, and severe AS, respectively). Increasing AS severity was associated with impaired MFR (P<0.001) and GLS (P<0.001), even when perfusion was normal. Statistically significant associations were noted between MFR and GLS, MFR and left ventricular ejection fraction, and MFR and left ventricular ejection fraction reserve. After a median follow-up of 349 (interquartile range, 116-662) days, 4 (7.4%), 5 (10.2%), and 6 (27.3%) patients experienced a major adverse cardiovascular event in the mild, moderate, and severe AS groups, respectively. In a matched-control analysis, patients with mild-to-moderate AS had higher rates of impaired MFR (52.9% versus 39.9%; P=0.048) and major adverse cardiovascular event (11.8% versus 3.0%; P=0.002).

CONCLUSIONS

Despite lack of ischemia, as severity of AS increased, MFR decreased and GLS worsened, reflecting worse coronary microvascular health and myocardial remodeling. Positron emission tomography-derived MFR showed a significant independent correlation with left ventricular ejection fraction and GLS. Patients with prosthetic aortic valve showed a high prevalence of impaired MFR.

TAVR in 2023: Who Should Not Get It?

Since the first transcatheter delivery of an aortic valve prosthesis was performed by Cribier et al in 2002, the picture of aortic stenosis (AS) therapeutics has changed dramatically. Initiated from an indication of inoperable to high surgical risk, extending to intermediate and low risk, transcatheter aortic valve replacement (TAVR) is now an approved treatment for patients with severe, symptomatic AS across all the risk categories. The current evidence supports TAVR as a frontline therapy for treating severe AS. The crucial question remains concerning the subset of patients who still are not ideal candidates for TAVR because of certain inherent anatomic, nonmodifiable, and procedure-specific factors. Therefore, in this study, we focus on these scenarios and reasons for referring selected patients for surgical aortic valve replacement in 2023.

Prosthesis-patient mismatch after transcatheter aortic valve implantation

Prosthesis-patient mismatch (PPM), first described in 1978, occurs when a prosthetic valve functions normally, but has an effective orifice area that is too small relative to the patient's body surface area. It results in residual left ventricular afterload and higher transvalvular pressure gradient, which has been considered to impair prognosis. PPM following surgical aortic replacement is reportedly associated with worse clinical outcomes, such as high mortality. However, the impact of PPM on clinical outcomes after transcatheter aortic valve implantation (TAVI) remains unclear. There is conflicting evidence on the impact of PPM following TAVI due to differences across studies in terms of follow-up period, methods, patient populations, and type of bioprosthetic valve. The present review summarizes the most recent evidence on PPM after TAVI.

Surgical Management of Complex Aortic Valve Disease in Young Adults: Repair, Replacement, and Future Alternatives

The ideal aortic valve substitute in young adults remains unknown. Prosthetic valves are associated with a suboptimal survival and carry a significant risk of valve-related complications in young patients, mainly reinterventions with tissue valves and, thromboembolic events and major bleeding with mechanical prostheses. The Ross procedure is the only substitute that restores a survival curve similar to that of a matched general population, and permits a normal life without functional limitations. Though the risk of reintervention is the Achilles' heel of this procedure, it is very low in patients with aortic stenosis and can be mitigated in patients with aortic regurgitation by tailored surgical techniques. Finally, the Ozaki procedure and the transcatheter aortic valve implantation are seen by many as future alternatives but lack evidence and long-term follow-up in this specific patient population.

Risk and Timing of Noncardiac Surgery After Transcatheter Aortic Valve Implantation

IMPORTANCE

Noncardiac surgery after transcatheter aortic valve implantation (TAVI) is a clinical challenge with concerns about safety and optimal management.

OBJECTIVES

To evaluate perioperative risk of adverse events associated with noncardiac surgery after TAVI by timing of surgery, type of surgery, and TAVI valve performance.

DESIGN, SETTING, AND PARTICIPANTS

This cohort study was conducted using data from a prospective TAVI registry of patients at the tertiary care University Hospital in Bern, Switzerland. All patients undergoing noncardiac surgery after TAVI were identified. Data were analyzed from November through December 2021.

EXPOSURES

Timing, clinical urgency, and risk category of noncardiac surgery were assessed among patients who had undergone TAVI and subsequent noncardiac surgery.

MAIN OUTCOMES AND MEASURES

A composite of death, stroke, myocardial infarction, and major or life-threatening bleeding within 30 days after noncardiac surgery.

RESULTS

Among 2238 patients undergoing TAVI between 2013 and 2020, 300 patients (mean [SD] age, 81.8 [6.6] years; 144 [48.0%] women) underwent elective (160 patients) or urgent (140 patients) noncardiac surgery after TAVI and were included in the analysis. Of these individuals, 63 patients (21.0%) had noncardiac surgery within 30 days of TAVI. Procedures were categorized into low-risk (21 patients), intermediate-risk (190 patients), and high-risk (89 patients) surgery. Composite end points occurred within 30 days of surgery among 58 patients (Kaplan-Meier estimate, 19.7%; 95% CI, 15.6%-24.7%). There were no significant differences in baseline demographics between patients with the 30-day composite end point and 242 patients without this end point, including mean (SD) age (81.3 [7.1] years vs 81.9 [6.5] years; P = .28) and sex (25 [43.1%] women vs 119 [49.2%] women; P = .37). Timing (ie, ≤30 days from TAVI to noncardiac surgery), urgency, and risk category of surgery were not associated with increased risk of the end point. Moderate or severe prosthesis-patient mismatch (adjusted hazard ratio [aHR], 2.33; 95% CI, 1.37-3.95; P = .002) and moderate or severe paravalvular regurgitation (aHR, 3.61; 95% CI 1.25-10.41; P = .02) were independently associated with increased risk of the end point.

CONCLUSIONS AND RELEVANCE

These findings suggest that noncardiac surgery may be performed early after successful TAVI. Suboptimal device performance, such as prosthesis-patient mismatch and paravalvular regurgitation, was associated with increased risk of adverse outcomes after noncardiac surgery.

Coronary Revascularization in Patients Undergoing Aortic Valve Replacement for Severe Aortic Stenosis

Aortic stenosis (AS) and coronary artery disease (CAD) frequently coexist, with up to two thirds of patients with AS having significant CAD. Given the challenges when both disease states are present, these patients require a tailored approach diagnostically and therapeutically. In this review the authors address the impact of AS and aortic valve replacement (AVR) on coronary hemodynamic status and discuss the assessment of CAD and the role of revascularization in patients with concomitant AS and CAD. Remodeling in AS increases the susceptibility of myocardial ischemia, which can be compounded by concomitant CAD. AVR can improve coronary hemodynamic status and reduce ischemia. Assessment of the significance of coexisting CAD can be done using noninvasive and invasive metrics. Revascularization in patients undergoing AVR can benefit certain patients in whom CAD is either prognostically or symptomatically important. Identifying this cohort of patients is challenging and as yet incomplete. Patients with dual pathology present a diagnostic and therapeutic challenge; both AS and CAD affect coronary hemodynamic status, they provoke similar symptoms, and their respective treatments can have an impact on both diseases. Decisions regarding coronary revascularization should be based on understanding this complex relationship, using appropriate coronary assessment and consensus within a multidisciplinary team.

Association of Myocardial Blood Flow Reserve With Adverse Left Ventricular Remodeling in Patients With Aortic Stenosis: The Microvascular Disease in Aortic Stenosis (MIDAS) Study

Importance

Impaired myocardial flow reserve (MFR) and stress myocardial blood flow (MBF) on positron emission tomography (PET) myocardial perfusion imaging may identify adverse myocardial characteristics, including myocardial stress and injury in aortic stenosis (AS).

Objective

To investigate whether MFR and stress MBF are associated with LV structure and function derangements, and whether these parameters improve after aortic valve replacement (AVR).

Design, Setting, and Participants

In this single-center prospective observational study in Boston, Massachusetts, from 2018 to 2020, patients with predominantly moderate to severe AS underwent ammonia N13 PET myocardial perfusion imaging for myocardial blood flow (MBF) quantification, resting transthoracic echocardiography (TTE) for assessment of myocardial structure and function, and measurement of circulating biomarkers for myocardial injury and wall stress. Evaluation of health status and functional capacity was also performed. A subset of patients underwent repeated assessment 6 months after AVR. A control group included patients without AS matched for age, sex, and summed stress score who underwent symptom-prompted ammonia N13 PET and TTE within 90 days.

Exposures

MBF and MFR quantified on ammonia N13 PET myocardial perfusion imaging.

Main Outcomes and Measures

LV structure and function parameters, including echocardiographic global longitudinal strain (GLS), circulating high-sensitivity troponin T (hs-cTnT), N-terminal pro-B-type natriuretic peptide (NT-pro BNP), health status, and functional capacity.

Results

There were 34 patients with AS (1 mild, 9 moderate, and 24 severe) and 34 matched control individuals. MFR was independently associated with GLS and LV ejection fraction, (β,-0.31; P = .03; β, 0.41; P = .002, respectively). Stress MBF was associated with hs-cTnT (unadjusted β, -0.48; P = .005) and log NT-pro BNP (unadjusted β, -0.37; P = .045). The combination of low stress MBF and high hs-cTnT was associated with higher interventricular septal thickness in diastole, relative wall thickness, and worse GLS compared with high stress MBF and low hs-cTnT (12.4 mm vs 10.0 mm; P = .008; 0.62 vs 0.46; P = .02; and -13.47 vs -17.11; P = .006, respectively). In 9 patients studied 6 months after AVR, mean (SD) MFR improved from 1.73 (0.57) to 2.11 (0.50) (P = .008).

Conclusions and Relevance

In this study, in AS, MFR and stress MBF were associated with adverse myocardial characteristics, including markers of myocardial injury and wall stress, suggesting that MFR may be an early sensitive marker for myocardial decompensation.

Mid-term clinical and health-related quality of life outcomes for the Trifecta bioprosthesis

Background

The Trifecta valve has been reported to have excellent hemodynamics. Controversy exists on occurrence of patient-prosthesis mismatch (PPM) and data on mid-term outcome is sparse. Health-related quality of life (HRQoL) assessment for the Trifecta valve has not been reported before. The aim of this study was to report the mid-term clinical and HRQoL outcomes in patients undergoing Trifecta valve implantation at our institution.

Methods

In this prospective, observational study, patients undergoing an aortic valve replacement (AVR) using the Trifecta valve were included. Data collection was retrospective from prospectively collected institutional database. Clinical and echocardiographic data were collected prospectively during follow-up. Quality of life was assessed using the Short Form-36 (SF-36) questionnaire.

Results

Forty-seven patients were included in the study of which 9 (19%) were women. Isolated AVR was carried out in 33 (70%) patients. In-hospital mortality and 30-day mortality were 1 (2.1%) and 2 (4.2%), respectively. With a mean indexed effective orifice area (iEOA) 0.96 ± 0.1, none of the patients had severe PPM. Moderate PPM was seen in 19%. The mean follow-up was 3 ± 1.7 years. The 5-year survival estimate was 83.2% in the overall cohort, 81.4% in the isolated and 87.5% in the concomitant procedure group. Freedom from re-operation and structural valve degeneration at 5 years was 95.7% and 97.8%. The mean physical health composite was 69.24 ± 2 and the mean mental health composite was 69.7 ± 25, indicating excellent mental and physical well-being among patients.

Conclusion

The Trifecta valve provides satisfactory hemodynamics, survival and freedom from re-operation and excellent HRQoL at mid-term follow-up.

Midterm outcomes of subcoronary stentless porcine valve versus stented aortic valve replacement

INTRODUCTION

Stentless porcine xenografts are versatile bioprosthetic valves with the advantage of improved hemodynamics that mimic the function of the native aortic valve. However, these bioprostheses are challenging to implant in the subcoronary position.

METHODS

All consecutive patients who underwent a bioprosthetic aortic valve replacement (AVR) were included from our institutional database. Cox regression analysis was preformed to determine significant predictors for mid term mortality as well as all cause, cardiac, and heart failure readmission.

RESULTS

Patients in the subcoronary stentless group were older and more likely to be female and were likely to have a higher Society of Thoracic Surgery risk of mortality. Survival was superior in the stented AVR cohort at 30-days (96.4% vs 90.5%; P < .001), 1-year (90.5% vs 71.6%; P < .001), and 5-year (74.5% vs 56.9%; P < .001) follow up. Acute kidney injury (16.22% vs 5.22%; P < .001) and blood product transfusion (70.27% vs 44.0%; P < .001) were higher in the stentless group. Multivariable analysis revealed subcoronary stentless implantation as a significant independent risk factor for mortality (hazards ratio: 1.92 [1.35,2.72]; P < .001).

CONCLUSION

Stentless porcine xenograft implantation with the Freestyle bioprosthetic in the subcoronary position can be successfully performed in select patients, but its use is associated with increased perioperative morbidity and mortality affecting midterm outcomes. Individual patient selection and surgeon experience are important to ensure favorable outcomes.

Pathophysiological coronary and microcirculatory flow alterations in aortic stenosis

Regulation of coronary blood flow is maintained through a delicate balance of ventriculoarterial and neurohumoral mechanisms. The aortic valve is integral to the functions of these systems, and disease states that compromise aortic valve integrity have the potential to seriously disrupt coronary blood flow. Aortic stenosis (AS) is the most common cause of valvular heart disease requiring medical intervention, and the prevalence and associated socio-economic burden of AS are set to increase with population ageing. Valvular stenosis precipitates a cascade of structural, microcirculatory, and neurohumoral changes, which all lead to impairment of coronary flow reserve and myocardial ischaemia even in the absence of notable coronary stenosis. Coronary physiology can potentially be normalized through interventions that relieve severe AS, but normality is often not immediately achievable and probably requires continued adaptation. Finally, the physiological assessment of coronary artery disease in patients with AS represents an ongoing challenge, as the invasive physiological measures used in current cardiology practice are yet to be validated in this population. This Review discusses the key concepts of coronary pathophysiology in patients with AS through presentation of contemporary basic science and data from animal and human studies.

[Surgical treatment of aortic valve stenosis]

Surgical aortic valve replacement still represents the gold standard in patients with severe symptomatic aortic valve stenosis. In addition to conventional aortic valve replacement by mechanical or biological prostheses via a median sternotomy, novel approaches including minimally invasive strategies and new devices, such as so-called rapid deployment prostheses, are becoming increasingly more established. Autologous replacement strategies including the Ross and the Ozaki procedures have evolved into reliable options at selected centers of excellence. These novel treatment approaches in aortic valve surgery result in excellent short and long-term outcomes with a reduction of procedure-related complications. Taken together, these modern surgical replacement strategies enable a personalized surgical treatment in patients with aortic valve stenosis, which are tailored to the individual patient.

In-vivo assessment of the morphology and hemodynamic functions of the BioValsalva™ composite valve-conduit graft using cardiac magnetic resonance imaging and computational modelling technology

BACKGROUND

The evaluation of any new cardiac valvular prosthesis should go beyond the classical morbidity and mortality rates and involve hemodynamic assessment. As a proof of concept, the objective of this study was to characterise for the first time the hemodynamics and the blood flow profiles at the aortic root in patients implanted with BioValsalva™ composite valve-conduit using comprehensive MRI and computer technologies.

METHODS

Four male patients implanted with BioValsalva™ and 2 age-matched normal controls (NC) underwent cardiac magnetic resonance imaging (MRI). Phase-contrast imaging with velocity-mapping in 3 orthogonal directions was performed at the level of the aortic root and descending thoracic aorta. Computational fluid dynamic (CFD) simulations were performed for all the subjects with patient-specific flow information derived from phase-contrast MR data.

RESULTS

The maximum and mean flow rates throughout the cardiac cycle at the aortic root level were very comparable between NC and BioValsalva™ patients (541 ± 199 vs. 567 ± 75 ml/s) and (95 ± 46 vs. 96 ± 10 ml/s), respectively. The maximum velocity (cm/s) was higher in patients (314 ± 49 vs. 223 ± 20; P = 0.06) due to relatively smaller effective orifice area (EOA), 2.99 ± 0.47 vs. 4.40 ± 0.24 cm2 (P = 0.06), however, the BioValsalva™ EOA was comparable to other reported prosthesis. The cross-sectional area and maximum diameter at the root were comparable between the two groups. BioValsalva™ conduit was stiffer than the native aortic wall, compliance (mm2 • mmHg(-1) • 10(-3)) values were (12.6 ± 4.2 vs 25.3 ± 0.4.; P = 0.06). The maximum time-averaged wall shear stress (Pa), at the ascending aorta was equivalent between the two groups, 17.17 ± 2.7 (NC) vs. 17.33 ± 4.7 (BioValsalva™ ). Flow streamlines at the root and ascending aorta were also similar between the two groups apart from a degree of helical flow that occurs at the outer curvature at the angle developed near the suture line.

CONCLUSIONS

BioValsalva™ composite valve-conduit prosthesis is potentially comparable to native aortic root in structural design and in many hemodynamic parameters, although it is stiffer. Surgeons should pay more attention to the surgical technique to maximise the reestablishment of normal smooth aortic curvature geometry to prevent unfavourable flow characteristics.

Incidence and sequelae of prosthesis-patient mismatch in transcatheter versus surgical valve replacement in high-risk patients with severe aortic stenosis: a PARTNER trial cohort--a analysis

BACKGROUND

Little is known about the incidence of prosthesis-patient mismatch (PPM) and its impact on outcomes after transcatheter aortic valve replacement (TAVR).

OBJECTIVES

The objectives of this study were: 1) to compare the incidence of PPM in the TAVR and surgical aortic valve replacement (SAVR) randomized control trial (RCT) arms of the PARTNER (Placement of AoRTic TraNscathetER Valves) I Trial cohort A; and 2) to assess the impact of PPM on regression of left ventricular (LV) hypertrophy and mortality in these 2 arms and in the TAVR nonrandomized continued access (NRCA) registry cohort.

METHODS

The PARTNER Trial cohort A randomized patients 1:1 to TAVR or bioprosthetic SAVR. Postoperative PPM was defined as absent if the indexed effective orifice area (EOA) was >0.85 cm(2)/m(2), moderate if the indexed EOA was ≥0.65 but ≤0.85 cm(2)/m(2), or severe if the indexed EOA was <0.65 cm(2)/m(2). LV mass regression and mortality were analyzed using the SAVR-RCT (n = 270), TAVR-RCT (n = 304), and TAVR-NRCA (n = 1,637) cohorts.

RESULTS

The incidence of PPM was 60.0% (severe: 28.1%) in the SAVR-RCT cohort versus 46.4% (severe: 19.7%) in the TAVR-RCT cohort (p < 0.001) and 43.8% (severe: 13.6%) in the TAVR-NRCA cohort. In patients with an aortic annulus diameter <20 mm, severe PPM developed in 33.7% undergoing SAVR compared with 19.0% undergoing TAVR (p = 0.002). PPM was an independent predictor of less LV mass regression at 1 year in the SAVR-RCT (p = 0.017) and TAVR-NRCA (p = 0.012) cohorts but not in the TAVR-RCT cohort (p = 0.35). Severe PPM was an independent predictor of 2-year mortality in the SAVR-RCT cohort (hazard ratio [HR]: 1.78; p = 0.041) but not in the TAVR-RCT cohort (HR: 0.58; p = 0.11). In the TAVR-NRCA cohort, severe PPM was not a predictor of 1-year mortality in all patients (HR: 1.05; p = 0.60) but did independently predict mortality in the subset of patients with no post-procedural aortic regurgitation (HR: 1.88; p = 0.02).

CONCLUSIONS

In patients with severe aortic stenosis and high surgical risk, PPM is more frequent and more often severe after SAVR than TAVR. Patients with PPM after SAVR have worse survival and less LV mass regression than those without PPM. Severe PPM also has a significant impact on survival after TAVR in the subset of patients with no post-procedural aortic regurgitation. TAVR may be preferable to SAVR in patients with a small aortic annulus who are susceptible to PPM to avoid its adverse impact on LV mass regression and survival. (The PARTNER Trial: Placement of AoRTic TraNscathetER Valve Trial; NCT00530894).

[Coronary microvascular dysfunction and aortic stenosis: an update]

The coronary microcirculatory impairment is a key feature of the pathophysiology of aortic stenosis (AS), the most operated valvular disease over the world. Several studies showed this coronary microcirculatory impairment in AS, using different tools and protocols, in various patient population of AS. This article will review the impairment of the coronary microcirculation in AS underlining its multifactorial origin, its functional part related to the hemodynamic consequences of AS, its complex relationship with left ventricular hypertrophy, and its potential diagnostic and prognostic value.

Coronary blood flow in patients with severe aortic stenosis before and after transcatheter aortic valve implantation

Patients with severe aortic stenosis and no obstructed coronary arteries are reported to have reduced coronary flow. Doppler evaluation of proximal coronary flow is feasible using transesophageal echocardiography. The present study aimed to assess the change in coronary flow in patients with severe aortic stenosis undergoing transcatheter aortic valve implantation (TAVI). The left main coronary artery was visualized using transesophageal echocardiography in 90 patients undergoing TAVI using the Edwards SAPIEN valve. The peak systolic and diastolic velocities of the coronary flow and the time-velocity integral were obtained before and after TAVI using pulse-wave Doppler. Mean aortic gradients decreased from 47.1 ± 15.7 mm Hg before TAVI to 3.6 ± 2.6 mm Hg after TAVI (p <0.001). The aortic valve area increased from 0.58 ± 0.17 to 1.99 ± 0.35 cm(2) (p <0.001). The cardiac output increased from 3.4 ± 1.1 to 3.8 ± 1.0 L/min (p <0.001). Left ventricular end-diastolic pressure (LVEDP) decreased from 19.8 ± 5.4 to 17.3 ± 4.1 mm Hg (p <0.001). The following coronary flow parameters increased significantly after TAVI: peak systolic velocity 24.2 ± 9.3 to 30.5 ± 14.9 cm/s (p <0.001), peak diastolic velocity 49.8 ± 16.9 to 53.7 ± 22.3 cm/s (p = 0.04), total velocity-time integral 26.7 ± 10.5 to 29.7 ± 14.1 cm (p = 0.002), and systolic velocity-time integral 6.1 ± 3.7 to 7.7 ± 5.0 cm (p = 0.001). Diastolic time-velocity integral increased from 20.6 ± 8.7 to 22.0 ± 10.1 cm (p = 0.04). Total velocity-time integral increased >10% in 43 patients (47.2%). Pearson's correlation coefficient revealed the change in LVEDP as the best correlate of change in coronary flow (R = -0.41, p = 0.003). In conclusion, TAVI resulted in a significant increase in coronary flow. The change in coronary flow was associated mostly with a decrease in LVEDP.

Long-term outcomes after elective isolated mechanical aortic valve replacement in young adults

OBJECTIVES

The aim of this study was to determine long-term survival and clinical outcomes after elective isolated mechanical aortic valve replacement in young adults.

METHODS

A clinical observational study was conducted in a cohort of 450 consecutive adults less than 65 years of age who had undergone elective isolated mechanical aortic valve replacement (AVR) between 1997 and 2006. Patients who had undergone previous cardiac surgery, and those undergoing concomitant procedures or urgent surgery were excluded. Follow-up was 93.3% complete with a mean follow-up of 9.1±3.5 years. The primary end point was survival. Life table analyses were used to determine age- and gender-matched general population survival. Secondary end points were reoperation and valve-related complications.

RESULTS

Overall actuarial survival at 1, 5, and 10 years was 98%±1%, 95%±1%, and 87%±1%, respectively, which was lower than expected in the age- and gender-matched general population in Quebec. Actuarial freedom from prosthetic valve dysfunction was 99%±0.4%, 95%±1%, and 91%±1% at 1, 5, and 10 years, respectively. Actuarial freedom from valve reintervention was 98%±1%, 96%±1%, and 94%±1% at 1, 5 and 10 years, respectively. Actuarial survival free from reoperation at 10 years was 82%±2%. Actuarial freedom from major hemorrhage was 98%±1%, 96%±1%, and 90%±2% at 1, 5, and 10 years, respectively.

CONCLUSIONS

In young adults undergoing elective isolated mechanical AVR, survival remains suboptimal compared with an age- and gender-matched general population. Furthermore, there is a low but constant hazard of prosthetic valve reintervention after mechanical AVR.

Influence of type of aortic valve prosthesis on coronary blood flow velocity

BACKGROUND

Severe aortic valve stenosis is associated with high resting and reduced hyperemic coronary blood flow. Coronary blood flow increases after aortic valve replacement (AVR); however, the increase depends on the type of prosthesis used. The present study investigates the influence of type of aortic valve prosthesis on coronary blood flow velocity.

METHODS

The blood flow velocity in the left anterior descending coronary artery (LAD) and the right coronary artery (RCA) was measured intraoperatively before and after AVR with a stentless bioprosthesis (Sorin Freedom Solo; n = 11) or a bileaflet mechanical prosthesis (St. Jude Medical Regent; n = 11). Measurements were made with an X-Plore epicardial Doppler probe (Medistim, Oslo, Norway) following induction of hyperemia with an adenosine infusion. Preoperative and postoperative echocardiography evaluations were used to assess valvular and ventricular function. Velocity time integrals (VTI) were measured from the Doppler signals and used to calculate the proportion of systolic VTI (SF), diastolic VTI (DF), and normalized systolic coronary blood flow velocities (NSF) and normalized diastolic coronary blood flow velocities (NDF).

RESULTS

The systolic proportion of the LAD VTI increased after AVR with the St. Jude Medical Regent prosthesis, which produced higher LAD SF and NSF values than the Sorin Freedom Solo prosthesis (SF, 0.41 ± 0.09 versus 0.29 ± 0.13 [P = .04]; NSF, 0.88 ± 0.24 versus 0.55 ± 0.17 [P = .01]). No significant changes in the LAD velocity profile were noted after valve replacement with the Sorin Freedom Solo, despite a significant reduction in transvalvular gradient and an increase in the effective orifice area. AVR had no effect on the RCA flow velocity profile.

CONCLUSION

The coronary flow velocity profile in the LAD was significantly influenced by the type of aortic valve prosthesis used. The differences in the LAD velocity profile probably reflect differences in valve design and the systolic transvalvular flow pattern.

Application of Regent mechanical valve in patients with small aortic annulus: 3-year follow-up

Background

Aortic valve replacement (AVR) with a small aortic annulus is always challenging for the cardiac surgeon. In this study, we sought to evaluate the midterm performance of implantation with a 17-mm or 19-mm St. Jude Medical Regent (SJM Regent) mechanical valve in retrospective consecutive cohort of patients with small aortic annulus (diameter ≤ 19 mm).

Methods

From January 2008 to April 2011, 40 patients (31 female, mean age = 47.2 ± 5.8 years) with small aortic annulus (≤19 mm in diameter) underwent aortic valve replacement with a 17-mm or 19-mm St. Jude Medical Regent (SJM Regent) mechanical valve. Preoperative mean body surface area, New York Heart Association class, and mean aortic annulus were 1.61 ± 0.26 m², 3.2 ± 0.4, and 18 ± 1.4 mm respectively. Patients were divided into two groups, according to the implantation of 17 mm SJM Regent mechanical valve (group 1, n = 18) or 19 mm SJM Regent valve (group 2, n = 22). All patients underwent echocardiography examination preoperatively and at one year post-operation.

Results

There were no early deaths in either group. Follow-up time averaged 36 ± 17.6 months. The mean postoperative New York Heart Association class was 1.3 ± 0.6 (p < 0.001). By echocardiography, in group 1, the left ventricular ejection fraction (LVEF), left ventricular fraction shortening (LVFS), and the indexed effective orifice area (EOAI) increased from 43.7% ± 11.6%, 27.3% ± 7.6%, and 0.70 ± 0.06 cm²/m² to 69.8 ± 9.3%, 41.4 ± 8.3%, and 0.92 ± 0.10 cm²/m² respectively (P < 0.05), while the left ventricular mass index (LVMI), and the aortic transvalvular pressure gradient decreased from 116.4 ± 25.4 g/m², 46.1 ± 8.5 mmHg to 86.7 ± 18.2 g/m² , 13.7 ± 5.2 mmHg respectively. In group 2, the LVEF, LVFS and EOAI increased from 45.9% ± 9.7%, 30.7% ± 8.0%, and 0.81 ± 0.09 cm²/m² to 77.4% ± 9.7%, 44.5% ± 9.6%, and 1.27 ± 0.11 cm²/m² respectively, while the LVMI, and the aortic transvalvular pressure gradient decreased from 118.3 ± 27.6 g/m², 44.0 ± 6.7 mmHg to 80.1 ± 19.7 g/m², 10.8 ± 4.1 mmHg as well. The prevalence of PPM was documented in 2 patients in Group 1.

Conclusions

Patients with small aortic annulus and body surface area, experienced satisfactory clinical improvement after aortic valve replacement with modern SJM Regent bileaflet prostheses.

Transcatheter aortic valve implantation in patients with severe aortic stenosis and small aortic annulus

OBJECTIVES

Valve hemodynamics and clinical outcomes among patients with a small aortic annulus who underwent transcatheter aortic valve implantation (TAVI) were examined.

BACKGROUND

The presence of a small aortic annulus may complicate the surgical management of patients with severe aortic stenosis (AS). TAVI is an alternative to aortic valve replacement (AVR) in high-risk patients, but few data exist on the results of TAVI in patients with a small aortic annulus.

METHODS

Between 2007 and 2010, 35 patients (mean age 79.2 ± 9.4 years) with severe AS and an aortic annulus diameter <20 mm (mean 18.5 ± 0.9 mm) underwent TAVI with a 23-mm Edwards SAPIEN bioprosthesis (Edwards Lifesciences, Inc., Irvine, California). Echocardiographic parameters and clinical outcomes were assessed prior to discharge and at 6, 12, and 24 months.

RESULTS

Procedural success was achieved in 34 patients (97.1%). There was 1 in-hospital death. Peak and mean transaortic gradients decreased from 76.3 ± 33.0 mm Hg and 45.2 ± 20.6 mm Hg at baseline to 21.8 ± 8.4 mm Hg and 11.7 ± 4.8 mm Hg post-procedure, respectively, both p < 0.0001. Mean indexed effective orifice area (IEOA) increased from 0.35 ± 0.10 cm(2)/m(2) at baseline to 0.90 ± 0.18 cm(2)/m(2) post-procedure, p < 0.0001. Severe prosthesis-patient mismatch (IEOA <0.65 cm(2)/m(2)) occurred in 2 patients (5.9%). At a mean follow-up of 14 ± 11 months, gradients remained low and 30 of the 31 remaining survivors were in New York Heart Association functional class I or II.

CONCLUSIONS

In high-risk patients with severe AS and a small aortic annulus, TAVI is associated with good post-procedural valve hemodynamics and clinical outcomes. TAVI may provide a reasonable alternative to conventional AVR in elderly patients with a small aortic annulus.

Pulmonary hypertension in cardiac surgery

Pulmonary hypertension is an important prognostic factor in cardiac surgery associated with increased morbidity and mortality. With the aging population and the associated increase severity of illness, the prevalence of pulmonary hypertension in cardiac surgical patients will increase. In this review, the definition of pulmonary hypertension, the mechanisms and its relationship to right ventricular dysfunction will be presented. Finally, pharmacological and non-pharmacological therapeutic and preventive approaches will be presented.

[Functional vascular alterations associated with aortic valve stenosis]

Degenerative changes, atherosclerotic process and calcification of valvular leaflets are mostly responsible for valvular aortic valve stenosis, but congenital bicuspid aortic valve and rheumatic fever in history are also known predisposing factors. Aortic valve stenosis is frequently associated with different functional vascular alterations. The aim of this review is to demonstrate these vascular alterations evaluated by non-invasive methods and underlying physiologic and pathophysiologic processes.

Enhanced left ventricular mass regression after aortic valve replacement in patients with aortic stenosis is associated with improved long-term survival

BACKGROUND

Aortic valve replacement in patients with aortic stenosis is usually followed by regression of left ventricular hypertrophy. More complete resolution of left ventricular hypertrophy is suggested to be associated with superior clinical outcomes; however, its translational impact on long-term survival after aortic valve replacement has not been investigated.

METHODS

Demographic, operative, and clinical data were obtained retrospectively through case note review. Transthoracic echocardiography was used to measure left ventricular mass preoperatively and at annual follow-up visits. Patients were classified according to their reduction in left ventricular mass at 1 year after the operation: group 1, less than 25 g; group 2, 25 to 150 g; and group 3, more than 150 g. Kaplan-Meier and multivariable Cox regression were used.

RESULTS

A total of 147 patients were discharged from the hospital after aortic valve replacement for aortic stenosis between 1991 and 2001. Preoperative left ventricular mass was 279 ± 98 g in group 1 (n = 47), 347 ± 104 g in group 2 (n = 62), and 491 ± 183 g in group 3 (n = 38) (P < .001). Mean time to last echocardiogram was 6.2 ± 3.2 years. Left ventricular mass at late follow-up was 310 ± 119 g in group 1, 267 ± 107 g in group 2, and 259 ± 96 g in group 3 (P = .05). Transvalvular gradients at follow-up were not significantly different among the groups (group 1, 24.8 ± 23 mm Hg; group 2, 21.4 ± 16 mm Hg; group 3, 14.7 ± 9 mm Hg) (P = .31). There was no difference in the prevalence of other factors influencing left ventricular mass regression such as ischemic heart disease or hypertension, valve type, or valve size used. Ten-year actuarial survival was not statistically different in patients with enhanced left ventricular mass regression when compared with the log-rank test (group 1, 51% ± 9%; group 2, 54% ± 8%; and group 3, 72% ± 10%) (P = .26). After adjustment, left ventricular mass reduction of more than 150 g was demonstrated as an independent predictor of improved long-term survival on multivariate analysis (P = .02).

CONCLUSIONS

Our study is the first to suggest that enhanced postoperative left ventricular mass regression, specifically in patients undergoing aortic valve replacement for aortic stenosis, may be associated with improved long-term survival. In view of these findings, strategies purported to be associated with superior left ventricular mass regression should be considered when undertaking aortic valve replacement.

Does stentless aortic valve implantation increase perioperative risk? A critical appraisal of the literature and risk of bias analysis

Stentless aortic valve replacement has potential benefits in terms of valve hemodynamics and clinical outcomes, although these may be offset by greater technical complexity of implantation with longer cardiopulmonary bypass and cross-clamp times compared with stented valves. Meta-analyses of the small number of published randomized trials have been limited by their lack of critical synthesis of the literature, including evaluation of the Risk of Bias. Our objective was to determine whether stentless aortic valves increase perioperative risk of mortality. We also examined secondary clinical outcomes of neurological, renal and respiratory complications as well as hemodynamic changes reported by studies following implantation of the two types of aortic prosthesis. The methodology used to answer this question was a rigorous meta-analysis of randomized controlled trials, using bias-assessment techniques designed to address limitations of conventional meta-analysis. Our findings show that many of the existing randomized trials have a high or uncertain risk of bias. Analysis of studies with low risk of bias reveals that stentless valves do not increase perioperative risk in terms of 30-day mortality and morbidity though neither do they exhibit benefits in hemodynamics or clinical outcomes compared with stented valves. Larger, more stringent randomized studies would be required to identify any robust clinical difference.

Intraoperative Hemodynamic Instability During and After Separation From Cardiopulmonary Bypass

Every year, more than 1 million patients worldwide undergo cardiac surgery. Because of the aging of the population, cardiac surgery will increasingly be offered to patients at a higher risk of complications. The consequence is a reduced physiological reserve and hence an increased risk of mortality. These issues will have a significant impact on future health care costs because the population undergoing cardiac surgery will be older and more likely to develop postoperative complications. One of the most dreaded complications in cardiac surgery is difficult separation from cardiopulmonary bypass (CPB). When separation from CPB is associated with right-ventricular failure, the mortality rate will range from 44% to 86%. Therefore, the diagnosis and the preoperative prediction of difficult separation from CPB will be crucial to improve the selection and care of patients and to prevent complications for this high-risk patient population.

Hydrodynamic comparison of biological prostheses during progressive valve calcification in a simulated exercise situation. An in vitro study

OBJECTIVE

Despite continuous development of anticalcification treatment for biological valve prostheses, calcification remains one major cause of structural failure. The following study investigates hemodynamics and changes in opening and closing kinematics in progressively calcified porcine and pericardial valves in a simulated exercise situation.

MATERIALS AND METHODS

Five pericardial (Edwards Perimount Magna) and five porcine (Medtronic Mosaic Ultra) aortic valve bioprostheses (23 mm) were investigated in an artificial circulation system (150 beats/min, cardiac output 8l/min). Leaflet kinematics were visualized with a high-speed camera (3000 frames/s). Valves were exposed to a calcifying solution for 6 weeks. Repeated testing was performed every week. All prostheses underwent X-ray and photographic examination including measurement of calcium content for evaluation of progressive calcification.

RESULTS

In the exercise situation pericardial valves demonstrated lower pressure gradients initially compared to the porcine valves (8.5+/-1.4 vs 11+/-1.6 mmHg), but significantly higher closing volume (5.3+/-1.2 ml vs 1.2+/-0.2 ml of stroke volume) leading to an equal total energy. Neither valve type demonstrated a significant increase in gradient or closing volume compared to the normal output situation. Opening and closing times were longer for pericardial valves after 6 weeks (opening time 42+/-10 ms vs 28+/-10 ms, closing time 84+/-12 vs 52+/-10 ms after 6 weeks). Pericardial valves calcified faster and more severely leading to an increase in gradients and closure volume.

CONCLUSIONS

In the exercise situation pericardial valves demonstrated superior systolic function compared to porcine valves. Therefore pericardial valves have some advantage in active patients due to the lower gradients. Total energy loss remained constant during progressive calcification for both valves. Leaflet opening and closing is faster in porcine valves; clinical impact of these findings is not known. Diastolic performance is also important and should always be tested also in vivo.