Siamak Mohammadi

High-Dose Tranexamic Acid Is an Independent Predictor of Early Seizure After Cardiopulmonary Bypass

BACKGROUND Risk factors associated with early seizure after cardiopulmonary bypass (CPB) were examined. The role of tranexamic acid in seizure development was evaluated. METHODS Early seizure was defined as a seizure occurring within 24 hours of CPB, without neurologic deficit or new lesion on brain imaging. Independent determinants of early seizure were examined by multivariate logistic regression modelling. RESULTS Between 2004 and 2009, early seizure occurred in 119 of 8,929 patients (1.3%). A significant increase in the yearly rate of early seizure was observed in 2004 (0.73%) vs 2009 (1.97%; p<0.0001). Multivariate analysis showed the following variables were independent predictors of early seizure: age older than 75 years (adjusted odds ratio [OR], 2.1; p=0.0001), open heart procedure (OR, 12.0; p<0.0001), preoperative renal failure (OR, 3.2; p<0.0001), peripheral vascular disease (OR, 1.8; p=0.02), and total tranexamic acid dose of 100 mg/kg or more (OR, 2.6; p<0.0001). Risk of seizure was related to tranexamic acid in a dose-dependent fashion, with higher doses associated with increased risk of seizure. The use of CO2 in a subset of patients undergoing open heart procedures did not decrease the incidence of early seizure (4.8% vs 2.5% for no CO2; p=0.27). Postoperative chest tube drainage and blood product use were similar between patients receiving low-dose and high-dose tranexamic acid. CONCLUSIONS High-dose tranexamic acid (≥100 mg/kg) is independently associated with an increased risk of early seizure. Future tranexamic acid trials should assess the blood-conserving effect of tranexamic acid at a lower dosage and specifically monitor for seizure occurrence.

Impact of residual regurgitation after aortic valve replacement

OBJECTIVES Mild-to-moderate aortic regurgitation (AR) is not infrequently encountered after standard aortic valve replacement, and reportedly more often following transcatheter aortic valve implantation. Patients are usually managed by observational follow-up, but the clinical significance and natural history of residual AR are unknown. The goal of this study was to determine its impact on the outcome of these patients. METHODS Between 1992 and 2011, 3201 consecutive patients underwent isolated standard aortic valve replacement in our institution. Of these, 135 patients (4.2%) were found to have paravalvular leak >1/4. Clinical, intraoperative as well as early and late postoperative outcome variables were studied. Factors associated with residual AR and their impact on survival were assessed by multivariate analysis. RESULTS Mean follow-up was 4.5 ± 3.4 years. The use of a bioprosthesis, longer cardiopulmonary bypass duration and preoperative atrial fibrillation were associated with a higher risk of presenting residual AR. Survival was negatively affected by commonly identified comorbidities (diabetes, stroke, pulmonary disease, renal failure, peripheral vascular disease) but also by the presence of >1/4 residual AR. Survival in the latter group was lower than for patients with ≤1/4 AR at all time points: 91.4 vs 96.7%, 77.5 vs 82.4% and 44.1 vs 54.5% at 1, 5 and 10 years, respectively (P < 0.01). CONCLUSIONS Postoperative residual AR >1/4 is an independent predictor of postoperative mortality and should be considered in the selection of surgical approach and management strategy for patients in need of standard and transcatheter aortic valve replacement.

Long-Term Clinical and Echocardiographic Follow-Up of the Freestyle Stentless Aortic Bioprosthesis

Background— Stentless aortic bioprostheses were designed to provide enhanced hemodynamic performance and potentially greater longevity. The present report describes the outcomes of patients with the Freestyle stentless bioprosthesis followed for ⩽18 years. Methods and Results— Between 1993 and 2011, 430 patients underwent primary aortic valve replacement with a Freestyle bioprosthesis in the subcoronary position. Mean age was 68.2±8.2 years. All of the clinical and echocardiographic data were collected prospectively. Mean overall follow-up was 9.1±4.4 years and was complete in all of the patients. In-hospital mortality was 3.5% (n=15). Overall, 10- and 15-year survival were 60.7% and 35.0%, respectively. Fifty-one patients required reoperation during follow-up, including 27 for structural valve deterioration (SVD). Overall, freedom from reoperation was 91.0% and 75.0% at 10 and 15 years, whereas freedom from reoperation for SVD was 95.9% and 82.3%, respectively. At 10 and 15 years, freedom from reoperation for SVD was 94.0% and 62.6% for patients <60 years of age and 96.3% and 88.4% for patients ≥60 years of age (P=0.002). The median time to explant for SVD was 10.7 years. SVD presented mostly as acute, severe aortic insufficiency attributed to leaflet tear (77.8%). The independent risk factors for reoperation for SVD were age <60 years (P=0.001) and dyslipidemia (P=0.02). Conclusions— Aortic valve replacement with the Freestyle bioprosthesis in a subcoronary position provides good long-term clinical and echocardiographic outcomes for patients >60 years of age. Severe aortic insufficiency with leaflet tear is the major mode of SVD leading to reoperation in these patients.

Sex-related discordance between aortic valve calcification and hemodynamic severity of aortic stenosis : is valvular fibrosis the explanation?

Rationale: Calcific aortic stenosis (AS) is characterized by calcium deposition in valve leaflets. However, women present lower aortic valve calcification loads than men for the same AS hemodynamic severity. Objective: We, thus, aimed to assess sex differences in aortic valve fibrocalcific remodeling. Methods and Results: One hundred and twenty-five patients underwent Doppler echocardiography and multidetector computed tomography within 3 months before aortic valve replacement. Explanted stenotic tricuspid aortic valves were weighed, and fibrosis degree was determined. Sixty-four men and 39 women were frequency matched for age, body mass index, hypertension, renal disease, diabetes mellitus, and AS severity. Mean age (75±9 years), mean gradient (41±18 mm Hg), and indexed aortic valve area (0.41±0.12 cm2/m2) were similar between men and women (all P≥0.18). Median aortic valve calcification (1973 [1124–3490] Agatston units) and mean valve weight (2.36±0.99 g) were lower in women compared with men (both P<0.0001). Aortic valve calcification density correlated better with valve weight in men (r2=0.57; P<0.0001) than in women (r2=0.26; P=0.0008). After adjustment for age, body mass index, aortic valve calcification density, and aortic annulus diameter, female sex was an independent risk factor for higher fibrosis score in AS valves (P=0.003). Picrosirius red staining of explanted valves showed greater amount of collagen fibers (P=0.01), and Masson trichrome staining revealed a greater proportion of dense connective tissue (P=0.02) in women compared with men. Conclusions: In this series of patients with tricuspid aortic valve and similar AS severity, women have less valvular calcification but more fibrosis compared with men. These findings suggest that the pathophysiology of AS and thus potential targets for drug development may be different according to sex.

Intermediate follow-up of a composite stentless porcine valved conduit of bovine pericardium in the pulmonary circulation

BACKGROUND In the pediatric population, glutaraldehyde-preserved bovine pericardium conduit containing a stentless porcine valve has been proposed as an alternative to homografts for right ventricular outflow tract reconstruction. METHODS Between June 1996 and March 2000, a total of 55 patients, 20 with truncus arteriosus, 21 with pulmonary atresia with ventricular septal defect, and 14 with miscellaneous defects, received this conduit. Median age at implantation was 3.4 months (range, 3 days to 19 years), and 27 patients (50%) were less than 3 months old. Clinical outcome, echocardiographic data, and pathologic analysis were recorded. End points for conduit failure were conduit replacement or dilation. A mean follow-up of 27 months (range, 2 to 46 months) was available for 47 survivors. RESULTS Procedure for conduit obstruction was required in 13 patients. The most common procedure was operation, and all but 3 patients had an unsuccessful balloon angioplasty before reoperation. Actuarial freedom from conduit dilation or reoperation was 93.6% (95% confidence limits, 82% to 99%), 81.9% (95% confidence limits, 64% to 91%), 77.8% (95% confidence limits, 39% to 78%), and 64.3% (95% confidence limits, 26% to 73%) at 1, 2, 3, and 4 postoperative years, respectively. Univariate analysis identified small conduit size as a risk factor for conduit obstruction. CONCLUSIONS Although this new conduit was not free from progressive obstruction, our clinical results (easy to work and good valvular function) and the availability in small sizes encouraged us to use it as an alternative to small-size homografts when those were not available.

Prosthetic Valve Endocarditis After Transcatheter Valve Replacement: A Systematic Review

OBJECTIVES The aim of this review is to describe the incidence, features, predisposing factors, and outcomes of prosthetic valve endocarditis (PVE) after transcatheter valve replacement (TVR). BACKGROUND Very few data exist on PVE after TVR. METHODS Studies published between 2000 and 2013 regarding PVE in patients with transcatheter aortic valve replacement (TAVR) or transcatheter pulmonary valve replacement (TPVR) were identified through a systematic electronic search. RESULTS A total of 28 publications describing 60 patients (32 TAVRs, 28 TPVRs) were identified. Most TAVR patients (66% male, 80 ± 7 years of age) had a very high-risk profile (mean logistic EuroSCORE: 30.4 ± 14.0%). In TPVR patients (90% male, 19 ± 6 years of age), PVE was more frequent in the stenotic conduit/valve (61%). The median time between TVR and infective endocarditis was 5 months (interquartile range: 2 to 9 months). Typical microorganisms were mostly found with a higher incidence of enterococci after TAVR (34.4%), and Staphylococcus aureus after TPVR (29.4%). As many as 60% of the TAVR-PVE patients were managed medically despite related complications such as local extension, embolism, and heart failure in more than 50% of patients. The valve explantation rate was 57% and 23% in balloon- and self-expandable valves, respectively. In-hospital mortality for TAVR-PVE was 34.4%. Most TPVR-PVE patients (75%) were managed surgically, and in-hospital mortality was 7.1%. CONCLUSIONS Most cases of PVE post-TVR involved male patients, with a very high-risk profile (TAVR) or underlying stenotic conduit/valve (TPVR). Typical, but different, microorganisms of PVE were involved in one-half of the TAVR and TPVR cases. Most TPVR-PVE patients were managed surgically as opposed to TAVR patients, and the mortality rate was high, especially in the TAVR cohort.

Is surgical intervention still indicated in recurrent aortic arch obstruction

BACKGROUND Introduction of balloon dilatation has become the standard treatment for recurrent aortic arch obstruction and has changed the therapeutic approach to patients with this disorder. OBJECTIVES Whether all patients with recurrent aortic arch obstruction are candidates for balloon dilatation remains unanswered. In addition, only few reports have tried to compare the results between patients undergoing balloon dilatation or redo operations. METHODS Since 1983, 97 patients underwent reintervention for recurrent aortic arch obstruction (42 dilations and 55 reoperations). Eight had immediate unsuccessful dilatation and were shifted to the surgical group (n = 63). The median age at reintervention was 21.7 months (10 days-45 years), and the median delay was 13.6 months (7 days-17 years). Anatomy of the aortic arch oriented the surgical approach to treat arch hypoplasia. It could be performed through a left thoracotomy in 52 patients, with extended end-to-end anastomosis in 34 patients, subclavian flap repair in 9 patients, conduit insertion in 6 patients, and patch enlargement in 3 patients. More recently, an anterior approach with cardiopulmonary bypass without circulatory arrest was applied to enlarge the patch in all the aortic arches. RESULTS There was one early death in the surgical intervention group and 2 late deaths in the dilation group. Major complications and recurrence were higher in the dilated group (4 vs 0, P <.01, and 14 vs 5, P <.0004, respectively). At a mean follow-up of 11.8 +/- 4.1 years in the surgical intervention group and 7.5 +/- 2.5 years in the dilated group, systemic hypertension was normalized in all but 5 patients in the surgical intervention group and 6 patients in the dilated group. CONCLUSION Reoperation for recurrent aortic arch obstruction can be performed safely, with low rates of mortality and morbidity. This approach should be considered versus balloon angioplasty, especially in patients older than 4 years and in the presence of aortic arch hypoplasia.

Transapical mitral implantation of a balloon-expandable valve in native mitral valve stenosis in a patient with previous transcatheter aortic valve replacement.

55-year-old woman, with a previous trans-catheter aortic valve replacement (TAVR)performed 5 years earlier by the transapicalapproach because of porcelain aorta (radiotherapyfor a Hodgkin lymphoma), developed progressiveheart failure (New York Heart Association func-tional class III). Echocardiography revealed a normo-functioning aortic bioprosthesis (mean gradient15 mm Hg; valve area 1.1 cm

Myocardial injury following transcatheter aortic valve implantation: insights from delayed-enhancement cardiovascular magnetic resonance.

AIMS The aim of this study was to evaluate the presence, localisation and extent of myocardial injury as determined by late gadolinium enhancement (LGE) on cardiovascular magnetic resonance (CMR) imaging in patients undergoing transcatheter aortic valve implantation (TAVI). METHODS AND RESULTS A total of 37 patients, who underwent successful TAVI with a balloon-expandable valve (transapical [TA], n=11; non-TA, n=26), were included. Cardiac biomarker (CK-MB and cTnT) levels were determined at baseline and following TAVI. CMR was performed within a week before and within 30 days following TAVI. Some increase in cardiac biomarkers was detected in 97% of the patients as determined by a rise in cTnT, and in 49% of the patients as determined by a rise in CK-MB. Following TAVI, no new myocardial necrosis defects were observed with the non-TA approach. Nonetheless, all patients who underwent TAVI through the TA approach had new focal myocardial necrosis in the apex, with a median myocardial extent and necrotic mass of 5% [2.0-7.0] and 3.5 g [2.3-4.5], respectively. CONCLUSIONS Although some increase in cardiac biomarkers of myocardial injury was systematically detected following TAVI, new myocardial necrosis as evaluated by CMR was observed only in patients undergoing the procedure through the TA approach, involving ~5% of the myocardium in the apex.

Bilateral mammary artery grafting increases postoperative mediastinitis without survival benefit in obese patients

OBJECTIVES The prevalence of obesity has risen in the last decade, increasing the percentage of obese patients who undergo cardiac surgery. Deep sternal wound infection (DSWI) is a rare but devastating postoperative complication, more often encountered in the obese population. DSWI is also associated with the use of bilateral internal mammary artery (BIMA), particularly in this high-risk population. The aim of this study is to determine the short-term and long-term outcomes following BIMA revascularization in obese patients. METHODS This is a single-centre retrospective cohort study using prospectively collected data including all obese patients who underwent coronary artery bypass grafting (CABG) surgery between April 1991 and April 2014. Preoperative demographic characteristics, operative and postoperative variables were taken from the computerized database of the hospital. A propensity score matching was conducted for the short- and long-term outcomes in the entire study population. RESULTS Results showed that 5608 patients with a body mass index of ≥30 kg/m2 underwent CABG during the studied period. After propensity scoring, 494 patients receiving BIMA were matched to 5089 patients receiving single internal mammary artery (SIMA). All preoperative characteristics were comparable except for a higher prevalence of left ventricular dysfunction and left main disease as well as higher mean EuroSCORE in the SIMA group. In the postoperative period, short-term mortality was comparable in the two groups (P = 0.68). In-hospital DSWI was also comparable (P = 0.10). However, when considering DSWI occurring after hospitalization (median time; 19 days), the latter was significantly lower in the SIMA than in the BIMA group (1.1 vs 3.2%; P < 0.0001). For long-term survival, no difference was observed between the BIMA and SIMA groups after appropriate matching (P = 0.22). CONCLUSIONS In obese patients, CABG surgery using BIMA instead of SIMA increased the risk of postoperative DSWI, without improving survival. According to our results, short-term postoperative risks of infection associated with BIMA are not offset by longer-term benefits in that patient population. Special care should be exerted when selecting conduits for myocardial revascularization in obese patients.