Mitral regurgitation increases systolic strains in remote zone and worsens left ventricular dyssynchrony in a swine model of ischemic cardiomyopathy.

Background: Ischemic mitral regurgitation (IMR) imposes volume overload on the left ventricle (LV), accelerating adverse LV remodeling. In this study, we sought to investigate the impact of volume overload due to IMR on regional myocardial contractile mechanics. Methods: Ten Yorkshire swine were induced with myocardial infarction (MI) by occluding the left circumflex coronary artery (LCx). Cardiac MRI was performed at baseline (BL) and 2.5 months (2.5M) post-MI. IMR was quantified with epicardial echocardiography 3 months post-MI. The animals were then assigned to 2 groups: no/mild MR (nmMR, n = 4) and moderate/severe MR (msMR, n = 6). MRI images were analyzed to assess infarction size, end-diastolic and end-systolic volume (EDV and ESV, respectively), ejection fraction (EF), longitudinal strain (LS), circumferential strain (CS), and systolic dyssynchrony index (SDI). The myocardial region was divided into infarction, border, and remote zones based on the LCx-supplied region. Results: There was no difference in the infarction size. Group-wise comparison of LS and CS between BL and 2.5M demonstrated that LS and CS in the infarction zone and the border zone decreased at 2.5M in both groups. However, LS and CS in the remote zone were elevated only in the msMR group (LS: -9.81 ± 3.96 vs. -12.58 ± 5.07, p < 0.01; CS; -12.78 ± 3.81 vs. -16.09 ± 3.33, p < 0.01) at 2.5M compared to BL. The SDI of CS was significantly elevated in the msMR group (0.1255 vs. 0.0974, p = 0.015) at 2.5M compared to BL. Conclusions: Elevated LS and CS in the remote zone were observed in moderate/severe MR and ventricular dyssynchrony. These elevated cardiac strains, coupled with ventricular dyssynchrony, may contribute to the progression of MR, thereby accelerating heart failure.

Transcatheter Myotomy to Reduce Left Ventricular Outflow Obstruction.

BACKGROUND: Left ventricular outflow tract (LVOT) obstruction is a source of morbidity in hypertrophic cardiomyopathy (HCM) and a life-threatening complication of transcatheter mitral valve replacement (TMVR) and transcatheter aortic valve replacement (TAVR). Available surgical and transcatheter approaches are limited by high surgical risk, unsuitable septal perforators, and heart block requiring permanent pacemakers. OBJECTIVES: The authors report the initial experience of a novel transcatheter electrosurgical procedure developed to mimic surgical myotomy. METHODS: We used septal scoring along midline endocardium (SESAME) to treat patients, on a compassionate basis, with symptomatic LVOT obstruction or to create space to facilitate TMVR or TAVR. RESULTS: In this single-center retrospective study between 2021 and 2023, 76 patients underwent SESAME. In total, 11 (14%) had classic HCM, and the remainder underwent SESAME to facilitate TMVR or TAVR. All had technically successful SESAME myocardial laceration. Measures to predict post-TMVR LVOT significantly improved (neo-LVOT 42 mm2 [Q1-Q3: 7-117 mm2] to 170 mm2 [Q1-Q3: 95-265 mm2]; P < 0.001; skirt-neo-LVOT 169 mm2 [Q1-Q3: 153-193 mm2] to 214 mm2 [Q1-Q3: 180-262 mm2]; P < 0.001). Among patients with HCM, SESAME significantly decreased invasive LVOT gradients (resting: 54 mm Hg [Q1-Q3: 40-70 mm Hg] to 29 mm Hg [Q1-Q3: 12-36 mm Hg]; P = 0.023; provoked 146 mm Hg [Q1-Q3: 100-180 mm Hg] to 85 mm Hg [Q1-Q3: 40-120 mm Hg]; P = 0.076). A total of 74 (97.4%) survived the procedure. Five experienced 3 of 76 (3.9%) iatrogenic ventricular septal defects that did not require repair and 3 of 76 (3.9%) ventricular free wall perforations. Neither occurred in patients treated for HCM. Permanent pacemakers were required in 4 of 76 (5.3%), including 2 after concomitant TAVR. Lacerations were stable and did not propagate after SESAME (remaining septum: 5.9 ± 3.3 mm to 6.1 ± 3.2 mm; P = 0.8). CONCLUSIONS: With further experience, SESAME may benefit patients requiring septal reduction therapy for obstructive hypertrophic cardiomyopathy as well as those with LVOT obstruction after heart valve replacement, and/or can help facilitate transcatheter valve implantation.

Prospective validation of a risk score to predict pacemaker implantation after transcatheter aortic valve replacement.

INTRODUCTION: The need for pacemaker is a common complication after transcatheter aortic valve replacement (TAVR). We previously described the Emory Risk Score (ERS) to predict the need for new pacemaker implant (PPM) after TAVR. Metrics included in the score are a history of syncope, pre-existing RBBB, QRS duration ≥140 ms, and prosthesis oversizing ≥16%. To prospectively validate the previously described risk score. METHODS: We prospectively evaluated all patients without pre-existing pacemakers, ICD, or pre-existing indications for pacing undergoing TAVR with the Edwards SAPIEN 3 prosthesis at our institution from March 2019 to December 2020 (n = 661). Patients were scored prospectively; however, results were blinded from clinical decision-making. The primary endpoint was PPM at 30 days after TAVR. Performance of the ERS was evaluated using logistic regression, a calibration curve to prior performance, and receiver operating characteristic (ROC) analysis. RESULTS: A total of 48 patients (7.3%) had PPM after TAVR. A higher ERS predicted an increased likelihood of PPM (OR 2.61, 95% CI: 2.05-3.25 per point, p < 0.001). There was good correlation between observed and expected values on the calibration curve (slope = 1.04, calibration at large = 0.001). The area under the ROC curve was 0.81 (95% CI [0.74-0.88], p < 0.001). CONCLUSIONS: The ERS prospectively predicted the need for PPM in a serial, real-world cohort of patients undergoing TAVR with a balloon-expandable prosthesis, confirming findings previously described in retrospective cohorts. Notably, the prospective performance of the score was comparable with that of the initial cohorts. The risk score could serve as a framework for preprocedural risk stratification for PPM after TAVR.

Hybrid Closure of Postinfarction Apical Ventricular Septal Defect Using Septal Occluder Device and Right Ventricular Free Wall: The Apical BASSINET Concept.

BACKGROUND: Postinfarction ventricular septal defect (VSD) is a catastrophic complication of myocardial infarction. Surgical repair still has poor outcomes. This report describes clinical outcomes after a novel hybrid transcatheter/surgical repair in patients with apical VSD. METHODS: Seven patients with postmyocardial infarction apical VSD underwent hybrid transcatheter repair via subxiphoid surgical access. A transcatheter occluder (Amplatzer Septal Occluder) with a trailing premounted suture was deployed through the right ventricular wall and through the ventricular septum into the left ventricular apex. The trailing suture was used to connect an anchor external to the right ventricular wall. Tension on the suture then collapses the right ventricular free wall against the septum and left ventricular occluder, thereby obliterating the VSD. Outcomes were compared with 9 patients who underwent surgical repair using either patch or primary suture closure. RESULTS: All patients had significant left-to-right shunt (Qp:Qs 2.5:1; interquartile range [IQR, 2.1-2.6] hybrid repair versus 2.0:1 [IQR, 2.0-2.5] surgical repair), and elevated right ventricular systolic pressure (62 [IQR, 46-71] versus 49 [IQR, 43-54] mm Hg, respectively). All had severely depressed stroke volume index (22 versus 21 mL/m2) with ≈45% in each group requiring mechanical support preprocedurally. The procedure was done 15 (IQR, 10-50) versus 24 (IQR, 10-134) days postmyocardial infarction, respectively. Both groups of patients underwent repair with technical success and without intraprocedural death. One patient in the hybrid group and 4 in the surgical group developed multiorgan failure. The hybrid group had a higher survival at discharge (86% versus 56%) and at 30 days (71% versus 56%), but similar at 1 year (57% versus 56%). During follow-up, 1 patient in each group required reintervention for residual VSD (hybrid: 9 months versus surgical: 5 days). CONCLUSIONS: Early intervention with a hybrid transcatheter/surgical repair may be a viable alternative to traditional surgery for postinfarction apical VSD.

Trends in surgical aortic valve replacement in pre- and post-transcatheter aortic valve replacement eras at a structural heart center.

Background: The advent of transcatheter aortic valve replacement (TAVR) has directly impacted the lifelong management of patients with aortic valve disease. The U.S. Food and Drug Administration has approved TAVR for all surgical risk: prohibitive (2011), high (2012), intermediate (2016), and low (2019). Since then, TAVR volumes are increasing and surgical aortic valve replacements (SAVR) are decreasing. This study sought to evaluate trends in isolated SAVR in the pre- and post-TAVR eras. Methods: From January 2000 to June 2020, 3,861 isolated SAVRs were performed at a single academic quaternary care institution which participated in the early trials of TAVR beginning in 2007. A formal structural heart center was established in 2012 when TAVR became commercially available. Patients were divided into the pre-TAVR era (2000-2011, n = 2,426) and post-TAVR era (2012-2020, n = 1,435). Data from the institutional Society of Thoracic Surgeons National Database was analyzed. Results: The median age was 66 years, similar between groups. The post-TAVR group had a statistically higher rate of diabetes, hypertension, dyslipidemia, heart failure, more reoperative SAVR, and lower STS Predicted Risk of Mortality (PROM) (2.0% vs. 2.5%, p < 0.0001). There were more urgent/emergent/salvage SAVRs (38% vs. 24%) and fewer elective SAVRs (63% vs. 76%), (p < 0.0001) in the post-TAVR group. More bioprosthetic valves were implanted in the post-TAVR group (85% vs. 74%, p < 0.0001). Larger aortic valves were implanted (25 vs. 23 mm, p < 0.0001) and more annular enlargements were performed (5.9% vs. 1.6%, p < 0.0001) in the post-TAVR era. Postoperatively, the post-TAVR group had less blood product transfusion (49% vs. 58%, p < 0.0001), renal failure (1.4% vs. 4.3%, p < 0.0001), pneumonia (2.3% vs. 3.8%, p = 0.01), shorter lengths of stay, and lower in-hospital mortality (1.5% vs. 3.3%, p = 0.0007). Conclusion: The approval of TAVR changed the landscape of aortic valve disease management. At a quaternary academic cardiac surgery center with a well-established structural heart program, patients undergoing isolated SAVR in the post-TAVR era had lower STS PROM, more implantation of bioprosthetic valves, utilization of larger valves, annular enlargement, and lower in-hospital mortality. Isolated SAVR continues to be performed in the TAVR era with excellent outcomes. SAVR remains an essential tool in the lifetime management of aortic valve disease.

Neutrophil-to-Lymphocyte Ratios in Patients Undergoing Aortic Valve Replacement: The PARTNER Trials and Registries.

Background The neutrophil-to-lymphocyte ratio (NLR) as a marker of systemic inflammation has been associated with worse prognosis in several chronic disease states, including heart failure. However, few data exist on the prognostic impact of elevated baseline NLR or change in NLR levels during follow-up in patients undergoing transcatheter or surgical aortic valve replacement (TAVR or SAVR) for aortic stenosis. Methods and Results NLR was available in 5881 patients with severe aortic stenosis receiving TAVR or SAVR in PARTNER (Placement of Aortic Transcatheter Valves) I, II, and S3 trials/registries (median [Q1, Q3] NLR, 3.30 [2.40, 4.90]); mean NLR, 4.10; range, 0.5-24.9) and was evaluated as continuous variable and categorical tertiles (low: NLR ≤2.70, n=1963; intermediate: NLR 2.70-4.20, n=1958; high: NLR ≥4.20, n=1960). No patients had known baseline infection. High baseline NLR was associated with increased risk of death or rehospitalization at 3 years (58.4% versus 41.0%; adjusted hazard ratio [aHR], 1.39; 95% CI, 1.18-1.63; P<0.0001) compared with those with low NLR, irrespective of treatment modality. In both patients treated with TAVR and patients treated with SAVR, NLR decreased between baseline and 2 years. A 1-unit observed decrease in NLR between baseline and 1 year was associated with lower risk of death or rehospitalization between 1 year and 3 years (aHR, 0.86; 95% CI, 0.82-0.89; P<0.0001). Conclusions Elevated baseline NLR was independently associated with increased subsequent mortality and rehospitalization after TAVR or SAVR. The observed decrease in NLR after TAVR or SAVR was associated with improved outcomes. Registration URL: https://www.clinicaltrials.gov; Unique identifier: NCT00530894, NCT0134313, NCT02184442, NCT03225001, NCT0322141.

Transcatheter Myotomy to Relieve Left Ventricular Outflow Tract Obstruction: The Septal Scoring Along the Midline Endocardium Procedure in Animals.

BACKGROUND: Left ventricular outflow tract obstruction complicates hypertrophic cardiomyopathy and transcatheter mitral valve replacement. Septal reduction therapies including surgical myectomy and alcohol septal ablation are limited by surgical morbidity or coronary anatomy and high pacemaker rates, respectively. We developed a novel transcatheter procedure, mimicking surgical myotomy, called Septal Scoring Along the Midline Endocardium (SESAME). METHODS: SESAME was performed in 5 naive pigs and 5 pigs with percutaneous aortic banding-induced left ventricular hypertrophy. Fluoroscopy and intracardiac echocardiography guided the procedures. Coronary guiding catheters and guidewires were used to mechanically enter the basal interventricular septum. Imparting a tip bend to the guidewire enabled intramyocardial navigation with multiple df. The guidewire trajectory determined the geometry of SESAME myotomy. The myocardium was lacerated using transcatheter electrosurgery. Cardiac function and tissue characteristics were assessed by cardiac magnetic resonance at baseline, postprocedure, and at 7- or 30-day follow-up. RESULTS: SESAME myotomy along the intended trajectory was achieved in all animals. The myocardium splayed after laceration, increasing left ventricular outflow tract area (753 to 854 mm2, P=0.008). Two naive pigs developed ventricular septal defects due to excessively deep lacerations in thin baseline septa. No hypertrophy model pig, with increased septal thickness and left ventricular mass compared with naive pigs, developed ventricular septal defects. One animal developed left axis deviation on ECG but no higher conduction block was seen in any animal. Coronary artery branches were intact on angiography with no infarction on cardiac magnetic resonance late gadolinium imaging. Cardiac magnetic resonance chamber volumes, function, flow, and global strain were preserved. No myocardial edema was evident on cardiac magnetic resonance T1 mapping. CONCLUSIONS: This preclinical study demonstrated feasibility of SESAME, a novel transcatheter myotomy to relieve left ventricular outflow tract obstruction. This percutaneous procedure using available devices, with a safe surgical precedent, is readily translatable into patients.

Ventricular reshaping with a beating heart implant improves pump function in experimental heart failure.

OBJECTIVE: The left ventricle remodels from an ellipsoidal/conical shape to a spherical shape after a myocardial infarction. The spherical ventricle is inefficient as a pumping chamber, has higher wall stresses, and can lead to congestive heart failure. We sought to investigate if restoring physiological ventricular shape with a beating heart implant improves pump function. METHODS: Rats were induced with a myocardial infarction, developing left ventricular dilatation and dysfunction, and becoming spherical over 3 weeks. Thereafter, they were randomized to undergo left ventricular reshaping with a beating heart implant (n = 19) or continue follow-up without an implant (n = 19). Biweekly echocardiography was performed until 12 weeks, with half the rats euthanized at 6 weeks and remaining at 12 weeks. At termination, invasive hemodynamic parameters and histopathology were performed. RESULTS: At 3 weeks after the infarction, rats had a 22% fall in ejection fraction, 31% rise in end diastolic volume, and 23% rise in sphericity. Transventricular implant reshaping reduced the volume by 12.6% and sphericity by 21%, restoring physiologic ventricular shape and wall stress. Over the 12-week follow-up, pump function improved significantly with better ventricular-vascular coupling in the reshaped hearts. In this group, cardiomyocyte cross-section area was higher and the cells were less elongated. CONCLUSIONS: Reshaping a postinfarction, failing left ventricle to restore its physiological conical shape significantly improves long-term pump function.

Undersizing mitral annuloplasty alters left ventricular mechanics in a swine model of ischemic mitral regurgitation.

OBJECTIVE: Undersizing mitral annuloplasty (UMA) is a frequently used surgical repair technique to correct ischemic mitral regurgitation in patients with heart failure. In this study, we sought to test the hypothesis that downsizing the mitral annulus can adversely affect the shape and mechanics of the left ventricle inhibiting its functional recovery. METHODS: Eighteen farm swine that underwent an inferolateral myocardial infarction and developed ischemic mitral regurgitation of >2+ severity after 2 months were assigned as follows: 9 swine received an undersized mitral annuloplasty, 6 received papillary muscle approximation (PMA), and 3 animals did not receive any other intervention. Animals lived another 3 months and cardiac magnetic resonance imaging was performed before termination to assess ventricle mechanics and function. RESULTS: Ejection fraction was comparable between the 2 repair groups before surgery, but was significantly lower in UMA at 38.89% ± 7.91% versus 50.83% ± 9.04% in the PMA group (P = .0397). Animals receiving UMA had lower regional peak fractional shortening and reduced systolic and diastolic radial velocities compared with PMA and in some regions were lower than sham. Animals that underwent UMA had higher circumferential strain than sham, but lower than PMA. UMA animals have lower longitudinal strain compared to sham group and lower LV torsion than PMA. CONCLUSIONS: Undersizing the mitral annulus with an annuloplasty ring can restore valvular competence, but unphysiologically impair ventricle mechanics. Mitral valve repair strategies should focus not only on restoring valve competence, but preserving ventricle mechanics.

Postoperative Atrial Fibrillation or Flutter Following Transcatheter or Surgical Aortic Valve Replacement: PARTNER 3 Trial.

OBJECTIVES: The aim of this study was to assess the incidence and prognostic impact of early and late postoperative atrial fibrillation or flutter (POAF) in patients with severe aortic stenosis (AS) treated with transcatheter aortic valve replacement (TAVR) or surgical aortic valve replacement (SAVR). BACKGROUND: There is an ongoing controversy regarding the incidence, recurrence rate, and prognostic impact of early (in-hospital) POAF and late (postdischarge) POAF in patients with AS undergoing TAVR or SAVR. METHODS: In the PARTNER (Placement of Aortic Transcatheter Valve) 3 trial, patients with severe AS at low surgical risk were randomized to TAVR or SAVR. Analyses were performed in the as-treated population excluding patients with preexistent atrial fibrillation or flutter. RESULTS: Among 781 patients included in the analysis, early POAF occurred in 152 (19.5%) (18 of 415 [4.3%] and 134 of 366 [36.6%] following TAVR and SAVR, respectively). Following discharge, 58 new or recurrent late POAF events occurred within 1 year following the index procedure in 55 of 781 patients (7.0%). Early POAF was not an independent predictor of late POAF following discharge (odds ratio: 1.04; 95% CI: 0.52-2.08; P = 0.90). Following adjustment, early POAF was not an independent predictor of the composite outcome of death, stroke, or rehospitalization (hazard ratio: 1.10; 95% CI: 0.64-1.92; P = 0.72), whereas late POAF was associated with an increased adjusted risk for the composite outcome (hazard ratio: 8.90; 95% CI: 5.02-15.74; P < 0.0001), irrespective of treatment modality. CONCLUSIONS: In the PARTNER 3 trial, early POAF was more frequent following SAVR compared with TAVR. Late POAF, but not early POAF, was significantly associated with worse outcomes at 2 years, irrespective of treatment modality.

Atrial Fibrillation and Outcomes After Transcatheter or Surgical Aortic Valve Replacement (from the PARTNER 3 Trial).

The prognostic impact of preexisting atrial fibrillation or flutter (AF) in low-risk patients with severe aortic stenosis treated with transcatheter (TAVR) or surgical aortic valve replacement (SAVR) remains unknown. In this sub-analysis of the PARTNER 3 trial of patients with severe aortic stenosis at low surgical risk randomized 1:1 to TAVR versus SAVR, clinical outcomes were analyzed at 2 years according to AF status. Among 948 patients included in the analysis (452 [47.7%] in the SAVR vs 496 [52.3%] in the TAVR arm), 168 (17.6%) patients had AF [88/452 (19.5%) and 80/496 (16.1%) treated with SAVR and TAVR, respectively]. At 2 years, patients with AF had higher unadjusted rates of the composite outcome of death, stroke or rehospitalization (21.2% vs 12.9%, p = 0.007) and rehospitalization alone (15.3% vs 9.4%, p = 0.03) but not all cause death (3.8% vs 2.6%, p = 0.45) or stroke (4.8% vs 2.6%, p = 0.12). In adjusted analyses, patients with AF had a higher risk for the composite outcome of death, stroke or rehospitalization (hazard ratio [HR] 1.80, 95% confidence interval [CI] 1.20-2.71, p = 0.0046) and rehospitalization alone (HR 1.8, 95% CI 0.12-2.9, p = 0.015), but not death or stroke. There was no interaction between treatment modality and AF on the composite outcome (Pinter = 0.83). In conclusion, preexisting AF in patients with severe AS at low surgical risk was associated with increased risk of the composite outcome of death, stroke or rehospitalization at 2 years, irrespective of treatment modality.

Safety of same-day discharge after uncomplicated, minimalist transcatheter aortic valve replacement in the COVID-19 era.

OBJECTIVES: We sought to evaluate the safety, efficacy and feasibility of same-day discharge after uncomplicated, minimalist TAVR. BACKGROUND: At the start of the COVID-19 pandemic, we created a same-day discharge (SDD) pathway after conscious sedation, transfemoral (minimalist) TAVR to help minimize risk of viral transmission and conserve hospital resources. Studies support that next-day discharge (NDD) for carefully selected patients following minimalist TAVR is safe and feasible. There is a paucity of data regarding the safety of SDD after TAVR. METHODS: In-hospital and 30 day outcomes of consecutive patients meeting pre-specified criteria for SDD after minimalist TAVR at our institution between March and July of 2020 were reviewed. Outcomes were compared to a NDD cohort from July 2018 through July 2020 that would have met SDD criteria. Primary endpoints were mortality, delayed pacemaker placement, stroke and cardiovascular readmission at 30 days. RESULTS: Twenty nine patients were discharged via the SDD pathway after TAVR. 128 prior NDD patients were identified who met all criteria for SDD. The STS scores were similar between the two groups (SDD 2.6% ±1.5 vs. NDD 2.3% ± 1.2). There were no deaths at 30 days in either group. There was no significant difference in delayed pacemaker placement (SDD 0% vs. NDD 0.8%, p > .99) or cardiovascular readmission (SDD 0% vs. NDD 5.5%, p = .35) at 30 days. CONCLUSIONS: Same day discharge following uncomplicated, minimalist TAVR in selected patients appears to be safe, achieving similar 30 day outcomes as a cohort of next day discharge patients.

Priorities in coronary artery bypass grafting: Is midterm survival more dependent on completeness of revascularization or multiple arterial grafts?

OBJECTIVE: Both completeness of revascularization and multiple arterial grafts (multiple arterial coronary artery bypass grafting) have been associated with increased midterm survival after coronary artery bypass grafting. The purpose of this study was to evaluate the relative impact of completeness of revascularization and multiple arterial coronary artery bypass grafting on midterm survival after coronary artery bypass grafting. METHODS: A retrospective review of 17,411 isolated, primary coronary artery bypass grafting operations from January 2002 to June 2016 at a US academic institution was performed. Patients were divided into groups based on complete or incomplete revascularization and number of arterial grafts. Inverse probability of treatment weighting based on the generalized propensity score was performed to minimize imbalance in preoperative characteristics. Between-group differences in outcomes were assessed using multivariable logistic and Cox regression analyses, incorporating the propensity score weights. RESULTS: Patients undergoing multiple arterial coronary artery bypass grafting in this study were younger, had fewer comorbid conditions, and had lower incidence of left main stenosis compared with patients undergoing single-arterial coronary artery bypass grafting. Short-term perioperative outcomes were similar between groups once propensity score weighting was used to minimize between-group differences in preoperative variables. Median follow-up in the entire population was 630 days, but was 1366 days in the cohort with data available from the Social Security Death Index. Multiple arterial coronary artery bypass grafting was protective for midterm survival compared with single arterial coronary artery bypass grafting, regardless of complete or incomplete revascularization or strategy (multiple arterial complete revascularization vs single-arterial complete revascularization: hazard ratio, 0.82; 95% confidence interval, 0.69-0.97; P = .02; multiple arterial incomplete revascularization vs single-arterial incomplete revascularization: hazard ratio, 0.70; 95% confidence interval, 0.53-0.90; P = .007). CONCLUSIONS: After controlling for preoperative comorbidities, multiple arterial coronary artery bypass grafting provides a modest midterm survival benefit over single-arterial coronary artery bypass grafting irrespective of completeness of revascularization, suggesting that when forced to choose, surgeons may elect to pursue multiple arterial conduits.

Papillary Muscle Approximation Reduces Systolic Tethering Forces and Improves Mitral Valve Closure in the Repair of Functional Mitral Regurgitation.

Background: Undersizing mitral annuloplasty (UMA) to repair functional mitral regurgitation lacks durability, as it forces leaflet coaptation without relieving the sub-leaflet tethering forces. In this biomechanical study, we demonstrate that papillary muscle approximation (PMA) prior to UMA can drastically relieve tethering forces and improve valve function, without the need for significant annular downsizing. Methods: An ex vivo model of functional mitral regurgitation (FMR) was used, in which pig mitral valves were geometrically perturbed to induce FMR, and the repairs were performed. Nine pig mitral valves were studied as follows: normal(baseline), functional mitral regurgitation (FMR), true-sized annuloplasty to 30mm (TSR), and undersized annuloplasty to 26mm (DSR); and concomitant papillary muscle approximation (PMA) at both ring sizes. Mitral regurgitation, valve kinematics, and chordal forces were measured and compared between groups. Results: FMR geometry induced a 16.31±7.33% regurgitant fraction, compared to none at baseline. 30mm/TSR reduced regurgitation to 6.05±5.63% and a 26mm/DSR to 5.06±6.76%. Addition of papillary muscle approximation prior to either rings, reduced regurgitation to 3.87±6.79% with the true sized ring (TSR+PMA), and 3.71±6.25% with the downsized ring (DSR+PMA). Peak anterior and posterior marginal chordal forces were elevated to 0.09±0.1N and 0.12±0.1N respectively with FMR, which were not reduced by annuloplasty of either sizes. Addition of PMA, reduced the forces significantly to 0.23±0.02N and 0.51±0.04N. Conclusion: This biomechanical study, demonstrates that papillary muscle approximation relieves tethering forces and when added to annuloplasty, and mobilizes the leaflets to achieve a good valve closure. Such a result could be achieved without the need for extensive annular downsizing.

Hemodynamic and transcriptomic studies suggest early left ventricular dysfunction in a preclinical model of severe mitral regurgitation.

OBJECTIVE: Primary mitral regurgitation is a valvular lesion in which the left ventricular ejection fraction remains preserved for long periods, delaying a clinical trigger for mitral valve intervention. In this study, we sought to investigate whether adverse left ventricular remodeling occurs before a significant fall in ejection fraction and characterize these changes. METHODS: Sixty-five rats were induced with severe mitral regurgitation by puncturing the mitral valve leaflet with a 23-G needle using ultrasound guidance. Rats underwent longitudinal cardiac echocardiography at biweekly intervals and hearts explanted at 2 weeks (n = 15), 10 weeks (n = 15), 20 weeks (n = 15), and 40 weeks (n = 15). Sixty age- and weight-matched healthy rats were used as controls. Unbiased RNA-sequencing was performed at each terminal point. RESULTS: Regurgitant fraction was 40.99 ± 9.40%, with pulmonary flow reversal in the experimental group, and none in the control group. Significant fall in ejection fraction occurred at 14 weeks after mitral regurgitation induction. However, before 14 weeks, end-diastolic volume increased by 93.69 ± 52.38% (P < .0001 compared with baseline), end-systolic volume increased by 118.33 ± 47.54% (P < .0001 compared with baseline), and several load-independent pump function indices were reduced. Transcriptomic data at 2 and 10 weeks before fall in ejection fraction indicated up-regulation of myocyte remodeling and oxidative stress pathways, whereas those at 20 and 40 weeks indicated extracellular matrix remodeling. CONCLUSIONS: In this rodent model of mitral regurgitation, left ventricular ejection fraction was preserved for a long duration, yet rapid and severe left ventricular dilatation, and biological remodeling occurred before a clinically significant fall in ejection fraction.

Sitagliptin for the prevention and treatment of perioperative hyperglycaemia in patients with type 2 diabetes undergoing cardiac surgery: A randomized controlled trial.

AIM: To assess whether treatment with sitagliptin, starting before surgery and continued during the hospital stay, can prevent and reduce the severity of perioperative hyperglycaemia in patients with type 2 diabetes undergoing coronary artery bypass graft (CABG) surgery. MATERIALS AND METHODS: We conducted a double-blinded, placebo-controlled trial in adults with type 2 diabetes randomly assigned to receive sitagliptin or matching placebo starting 1 day prior to surgery and continued during the hospital stay. The primary outcome was difference in the proportion of patients with postoperative hyperglycaemia (blood glucose [BG] > 10 mmol/L [>180 mg/dL]) in the intensive care unit (ICU). Secondary endpoints included differences in mean daily BG in the ICU and after transition to regular wards, hypoglycaemia, hospital complications, length of stay and need of insulin therapy. RESULTS: We included 182 participants randomized to receive sitagliptin or placebo (91 per group, age 64 ± 9 years, HbA1c 7.6% ± 1.5% and diabetes duration 10 ± 9 years). There were no differences in the number of patients with postoperative BG greater than 10 mmol/L, mean daily BG in the ICU or after transition to regular wards, hypoglycaemia, hospital complications or length of stay. There were no differences in insulin requirements in the ICU; however, sitagliptin therapy was associated with lower mean daily insulin requirements (21.1 ± 18.4 vs. 32.5 ± 26.3 units, P = .007) after transition to a regular ward compared with placebo. CONCLUSION: The administration of sitagliptin prior to surgery and during the hospital stay did not prevent perioperative hyperglycaemia or complications after CABG. Sitagliptin therapy was associated with lower mean daily insulin requirements after transition to regular wards.