Novel Entropy-Based Metrics for Long-Term Atrial Fibrillation Recurrence Prediction Following Surgical Ablation: Insights from Preoperative Electrocardiographic Analysis.

Atrial fibrillation (AF) is a prevalent cardiac arrhythmia often treated concomitantly with other cardiac interventions through the Cox-Maze procedure. This highly invasive intervention is still linked to a long-term recurrence rate of approximately 35% in permanent AF patients. The aim of this study is to preoperatively predict long-term AF recurrence post-surgery through the analysis of atrial activity (AA) organization from non-invasive electrocardiographic (ECG) recordings. A dataset comprising ECGs from 53 patients with permanent AF who had undergone Cox-Maze concomitant surgery was analyzed. The AA was extracted from the lead V1 of these recordings and then characterized using novel predictors, such as the mean and standard deviation of the relative wavelet energy (RWEm and RWEs) across different scales, and an entropy-based metric that computes the stationary wavelet entropy variability (SWEnV). The individual predictors exhibited limited predictive capabilities to anticipate the outcome of the procedure, with the SWEnV yielding a classification accuracy (Acc) of 68.07%. However, the assessment of the RWEs for the seventh scale (RWEs7), which encompassed frequencies associated with the AA, stood out as the most promising individual predictor, with sensitivity (Se) and specificity (Sp) values of 80.83% and 67.09%, respectively, and an Acc of almost 75%. Diverse multivariate decision tree-based models were constructed for prediction, giving priority to simplicity in the interpretation of the forecasting methodology. In fact, the combination of the SWEnV and RWEs7 consistently outperformed the individual predictors and excelled in predicting post-surgery outcomes one year after the Cox-Maze procedure, with Se, Sp, and Acc values of approximately 80%, thus surpassing the results of previous studies based on anatomical predictors associated with atrial function or clinical data. These findings emphasize the crucial role of preoperative patient-specific ECG signal analysis in tailoring post-surgical care, enhancing clinical decision making, and improving long-term clinical outcomes.

Quantitative Transthoracic Echocardiography of the Response to Dobutamine in Cardiac Surgery Patients With Low Cardiac Output Syndrome.

OBJECTIVE: To quantify the acute effects of dobutamine in postoperative low cardiac output syndrome (LCOS) using transthoracic echocardiographic, hemodynamic, and blood biomarker monitoring and to assess its association with clinical outcomes. DESIGN: Observational prospective study. SETTING: Single university hospital. PARTICIPANTS: Patients undergoing elective cardiac surgery. INTERVENTIONS: None. MEASUREMENTS AND MAIN RESULTS: Echocardiographic parameters, hemodynamic data, and plasma biomarkers were obtained before and early after inotrope initiation. The diagnostic value of transthoracic echocardiographic parameters and their association with clinical outcome were evaluated. Thirty-eight LCOS patients and 12 control patients were included. The left ventricular outflow tract velocity time integral was significantly lower in LCOS patients (11.75 v 19.08 cm; p < 0.001) and showed a marked improvement after dobutamine administration (∼37% increase). Dobutamine improved left and right ventricular function, increased mean arterial pressure and urine output, and lowered lactate levels. The duration of dobutamine support, but not in-hospital mortality, was associated with echocardiographic estimates of cardiac performance early after dobutamine initiation. CONCLUSIONS: Early transthoracic echocardiographic assessment and the acute response to inotropic therapy may provide rapid and highly valuable information in the diagnostic workup and risk evaluation of patients with suspected LCOS after cardiac surgery.

mRNA PGC-1α levels in blood samples reliably correlates with its myocardial expression: study in patients undergoing cardiac surgery.

OBJECTIVE: Peroxisome proliferator-activated receptor-γ coactivator-1α (PGC-1α) is a transcriptional coactivator that has been proposed to play a protective role in mouse models of cardiac ischemia and heart failure, suggesting that PGC-1α could be relevant as a prognostic marker. Our previous studies showed that the estimation of peripheral mRNA PGC-1α expression was feasible and that its induction correlated with the extent of myocardial necrosis and left ventricular remodeling in patients with myocardial infarction. In this study, we sought to determine if the myocardial and peripheral expressions of PGC-1α are well correlated and to analyze the variability of PGC-1α expression depending on the prevalence of some metabolic disorders. METHODS: This was a cohort of 35 consecutive stable heart failure patients with severe aortic stenosis who underwent an elective aortic valve replacement surgery. mRNA PGC-1α expression was simultaneously determined from myocardial biopsy specimens and blood samples obtained during surgery by quantitative PCR, and a correlation between samples was made using the Kappa index. Patients were divided into two groups according to the detection of baseline expression levels of PGC-1α in blood samples, and comparisons between both groups were made by chi-square test or unpaired Student's t-test as appropriate. RESULTS: Based on myocardial biopsies, we found that mRNA PGC-1α expression in blood samples showed a statistically significant correlation with myocardial expression (Kappa index 0.66, p<0.001). The presence of higher systemic PGC-1α expression was associated with a greater expression of some target genes such as silent information regulator 2 homolog-1 (x-fold expression in blood samples: 4.43±5.22 vs. 1.09±0.14, p=0.044) and better antioxidant status in these patients (concentration of Trolox: 0.40±0.05 vs. 0.34±0.65, p=0.006). CONCLUSIONS: Most patients with higher peripheral expression also had increased myocardial expression, so we conclude that the non-invasive estimation of mRNA PGC-1α expression from blood samples provides a good approach of the constitutive status of the mitochondrial protection system regulated by PGC-1α and that this could be used as prognostic indicator in cardiovascular disease.

Is off-pump technique a safer procedure for coronary revascularization? A propensity score analysis of 20 years of experience.

OBJECTIVES: We aim to describe our experience in coronary artery bypass grafting (CABG) with or without cardiopulmonary bypass by comparing intraoperative and postoperative outcomes. METHODS: From January 1993 to June 2013, 3097 patients underwent consecutive emergency and scheduled CABG surgery. A total of 1770 patients underwent on-pump CABG (ONCABG) and 1327 off-pump CABG (OPCABG). A propensity score matching was performed to identify appropriate matched-pair patients; univariable and multivariable logistic regression analyses were performed to assess significant predictors of hospital and 30-day morbidity and mortality composite end-points. Morbidity composite end-point was defined as any renal, pulmonary, cardiovascular and neurological complication that occurred during hospital stay. We collected all-cause mortality data during the study period. RESULTS: We identified 1004 patients in each group. There were no significant differences in thirty day mortality, 2.8 vs 3.8%, in OPCABG and ONCABG, respectively (P = 0.21). Cardiovascular, neurological, respiratory and renal complications were more frequent in the ONCABG group: 13.9 vs 8.7% (P < 0.001), 3.9 vs 2.2% (P = 0.03), 13.5 vs 7.5% (P < 0.001), 7.1 vs 5.3% (P = 0.095), respectively. The long-term all-cause mortality rate was 12.3 vs 12.9% in the OPCABG versus ONCABG group (P = 0.42), respectively. In both uni- and multivariable analysis preoperative renal failure, chronic obstructive pulmonary disease and ONCABG were independent predictors of mortality and morbidity composite end-points. CONCLUSIONS: OPCABG is associated with less postoperative morbimortality and shorter hospital and intensive care unit length of stay. ONCABG resulted as an independent predictor of morbidity and mortality composite end-point. No statistically significant differences were observed in long-term all-cause mortality between groups.

Preoperative study of the surface ECG for the prognosis of atrial fibrillation maze surgery outcome at discharge.

The Cox-maze surgery is an effective procedure for terminating atrial fibrillation (AF) in patients requiring open-heart surgery associated with another heart disease. After the intervention, regardless of the patient's rhythm, all are treated with oral anticoagulants and antiarrhythmic drugs prior to discharge. Furthermore, patients maintaining AF before discharge could also be treated with electrical cardioversion (ECV). In view of this, a preoperative prognosis of the patient's rhythm at discharge would be helpful for optimizing drug therapy planning as well as for advancing ECV therapy. This work analyzes 30 preoperative electrocardiograms (ECGs) from patients suffering from AF in order to predict the Cox-maze surgery outcome at discharge. Two different characteristics of the AF pattern have been studied. On the one hand, the atrial activity (AA) organization, which provides information about the number of propagating wavelets in the atria, was investigated. AA organization has been successfully used in previous studies related to spontaneous reversion of paroxysmal AF and to the outcome of ECV. To assess organization, the dominant atrial frequency (DAF) and sample entropy (SampEn) have been computed. On the other hand, the second characteristic studied was the fibrillatory wave (f-wave) amplitude, which has been demonstrated to be a valuable indicator of the Cox-maze surgery outcome in previous studies. Moreover, this parameter has been obtained through a new methodology, based on computing the f-wave average power (fWP). Finally, all the computed indices were combined in a decision tree in order to improve prediction capability. Results for the DAF yielded a sensitivity (Se), a specificity (Sp) and an accuracy (Acc) of 61.54%, 82.35% and 73.33%, respectively. For SampEn the values were 69.23%, 76.00% and 73.33%, respectively, and for fWP they were 92.31%, 82.35% and 86.67%, respectively. Finally, the decision tree combining the three parameters analyzed improved the preoperative prognosis of the Cox-maze outcome with values of Se, Sp and Acc of 100%, 82.35% and 90%, respectively. As a consequence, the analysis of parameters related to the f-wave pattern, extracted from the preoperative ECG, has provided a considerable ability to predict the outcome of AF Cox-maze surgery at discharge.

Artificial chordae in the setting of complex mitral valve repair: early outcomes using the folding leaflet technique.

OBJECTIVES: Neochordal repair is particularly limited in case of large prolapse with absence of a reference point on a nearby segment. Our aim was to overcome these limitations by means of a simple technique: the 'Folding Leaflet'. METHODS: Ninety-six patients underwent this technique between January 2009 and August 2012 from a global mitral valve (MV) repair group of 384 patients. A subgroup of 68 patients with complex lesions, bileaflet, commissural or multisegment prolapse, was selected. These more challenging patients were considered as the study group in order to assess the efficacy of our technique. The neochordae were fixed to the papillary muscle with a simple stitch and then were passed through the free margin of the prolapsing leaflet. Free-edge remodelling was achieved weaving this suture and surpassing the coaptation line. Then, the leaflet was folded and its free margin was temporarily approximated edge-to-edge to the adjacent annulus. This was used as the reference point while the neochordae were tied without the need for adjacent healthy chordae or use of callipers. Complete echocardiographic follow-up was obtained at 6-month intervals. RESULTS: All patients had ≥ 2 prolapsed segments: posterior leaflet (40 patients), anterior leaflet (13 patients) or both leaflets (15 patients). Annuloplasty was routinely used and the mean number of neochordae per patient was 4.1 ± 2.2 (2-13). Mean follow-up was 28 ± 14 months (5-49 months). There was only one in-hospital death. Another patient died by pneumoniae (15th postoperative month). At the first-month follow-up, 51 patients had no mitral regurgitation (MR) and 16 patients had Grade 1 MR. Only 1 patient had more than mild regurgitation at the 6-month follow-up. There was no evidence of Grade 3 or 4 MR in any patient. At the 2-year follow-up, 34 patients remained with no MR or trace MR and 7 patients had Grade 1 MR. CONCLUSIONS: MV repair for complex degenerative MR using this technique of neochordal repair results in excellent early and mid-term outcomes. This technique facilitates the extensive use of neochordae in case of large areas of prolapse.

A multicentre Spanish study for multivariate prediction of perioperative in-hospital cerebrovascular accident after coronary bypass surgery: the PACK2 score.

OBJECTIVES: To develop a multivariate predictive risk score of perioperative in-hospital stroke after coronary artery bypass grafting (CABG) surgery. METHOD: A total of 26 347 patients were enrolled from 21 Spanish hospital databases. Logistic regression analysis was used to predict the risk of perioperative stroke (ictus or transient ischaemic attack). The predictive scale was developed from a training set of data and validated by an independent test set, both selected randomly. The assessment of the accuracy of prediction was related to the area under the ROC curve. The variables considered were: preoperative (age, gender, diabetes mellitus, arterial hypertension, previous stroke, cardiac failure and/or left ventricular ejection fraction<40%, non-elective priority of surgery, extracardiac arteriopathy, chronic kidney failure and/or creatininemia≥2 mg/dl and atrial fibrillation) and intraoperative (on/off-pump). RESULTS: Global perioperative stroke incidence was 1.38%. Non-elective priority of surgery (priority; OR=2.32), vascular disease (arteriopathy; OR=1.37), cardiac failure (cardiac; OR=3.64) and chronic kidney failure (kidney; OR=6.78) were found to be independent risk factors for perioperative stroke in uni- and multivariate models in the training set of data; P<0.0001; AUC=0.77, 95% CI 0.73-0.82. The PACK2 stroke CABG score was established with 1 point for each item, except for chronic kidney failure with 2 points (range 0-5 points); AUC=0.76, 95% CI 0.72-0.80. In patients with PACK2 score≥2 points, off-pump reduced perioperative stoke incidence by 2.3% when compared with on-pump CABG. CONCLUSIONS: PACK2 risk scale shows good predictive accuracy in the data analysed and could be useful in clinical practice for decision making and patient selection.

Impact of increasing degrees of renal impairment on outcomes of coronary artery bypass grafting: the off-pump advantage.

OBJECTIVES: Increasing degrees of renal impairment are associated with higher rates of morbimortality after coronary artery bypass grafting (CABG). This incremental risk has not been well studied in off-pump procedures (OPCAB). We assessed its impact on OPCAB and on-pump CABG (ONCAB). METHODS: A total of 1769 patients undergoing primary CABG (January 1995 through June 2011) had complete data on glomerular filtration rate (eGFR). 930 patients had Stage 2 renal insufficiency, 330 Stage 3, 27 Stage 4 and 465 normal renal function (Stage 1). Seventeen patients with end-stage disease (Stage 5) were excluded. The OPCAB technique was selectively used in 350 high-risk patients. Preoperative variables and postoperative outcomes were compared among eGFR subgroups and between matched and unmatched OPCAB vs ONCAB groups. RESULTS: Stages 3-4 patients were older (P < 0.0001), with higher prevalence of diabetes (36.8, 35.0, 39.7 and 74.1%, P < 0.01, 1-4 eGFR groups) peripheral arteriopathy (6.0, 9.0, 15.8 and 29.6%, P < 0.0001) and lower left ventricular ejection fraction (LVEF) (GFR-LVEF correlation: Pearson: 0.12, P < 0.0001). On-pump GFR groups had increasingly higher in-hospital mortality (1.0, 1.2, 3.5 and 15.4%, P < 0.0001), but no differences were observed in OPCAB (5.5, 4.8, 5.4 and 7.1%, P = 0.97). Similar trends on in-hospital morbidity were observed in ONCAB vs OPCAB groups: low cardiac output (P < 0.01), pneumonia (P < 0.01) and stroke (P < 0.05). GFR only predicted mortality in ONCAB patients (odds ratio (OR): 0.96, 95% CI: 0.94-0.98; P < 0.01). Patients with higher eGFR stages had statistically more reduced long-term survival, and this pattern was similar in the three treatment groups, also including the OPCAB group, who had the lowest survival in patients with eGFR stage 4. CONCLUSIONS: Patients with low GFR (Stages 3-4) undergoing ONCAB were at increased risk of early morbimortality. In contrast, there were no significant differences in operative morbimortality among eGFR groups in OPCAB patients. This 'off-pump advantage' on early outcomes was not observed at the long-term follow-up.

Off-pump surgery in preventing perioperative stroke after coronary artery bypass grafting: a retrospective multicentre study.

OBJECTIVES: To determine the effect of the off-pump technique in preventing stroke development during the early perioperative period after coronary artery bypass graft surgery (CABG). METHODS: Patients undergoing isolated CABG surgery were enrolled from 21 Spanish cardiac-surgery centres. Baseline variables related to perioperative stroke risk were recorded in the preoperative (age, gender, diabetes mellitus, arterial hypertension, prior stroke, cardiac failure: preoperative New York Heart Association class III-IV and/or left ventricular ejection fraction <40%, non-elective priority of surgery, peripheral arteriopathy, chronic renal failure) and intraoperative periods (on/off-pump performance). The Northern New England Cardiovascular Disease Study Group (NNECDSG) stroke risk schema was used to stratify stroke risk and compare observed neurological outcomes in this study. RESULTS: A total of 26 347 patients were included in the study. Global perioperative stroke incidence was 1.38%. Non-elective priority of surgery (OR = 2.37), peripheral arteriopathy (OR = 1.62), cardiac failure (OR = 2.98), prior stroke (OR = 1.57) and chronic renal failure (OR = 6.16) were found to be independent risk factors for perioperative stroke in uni- and multivariate models; Hosmer-Lemeshow test: χ(2) = 4.62, P = 0.59. Perioperative stroke incidence increased whenever NNECDSG score or the number of preoperative risk factors increased. However, on- vs off-pump surgery did not show statistical differences in NNECDSG strata. For patients with two or more preoperative independent risk factors, off-pump surgery showed a significant reduction in perioperative stroke incidence (4.29 vs 6.76%, P < 0.05), particularly when one of these factors was chronic renal failure or preoperative cardiac failure. However, when both factors were present concomitantly there was no difference between on and off-pump techniques, P < 0.0001. CONCLUSIONS: Off-pump surgery has a lower perioperative stroke incidence than on-pump only in cases associated with cardiovascular stroke-risk factors, in particular, with chronic renal failure and preoperative cardiac failure, but also with peripheral arteriopathy, prior stroke and non-elective surgery. The perioperative stroke rate remains high in cases with two or more preoperative stroke risk factors, even when using the off-pump technique, particularly when chronic renal failure is present.

Minimally invasive aortic valve surgery. A safe and useful technique beyond the cosmetic benefits.

INTRODUCTION AND OBJECTIVES: The aim of this study was to compare the in-hospital clinical outcomes of minimally invasive, isolated aortic valve replacement vs median sternotomy. METHODS: Between 2005 and 2012, 615 patients underwent aortic valve replacement at a single institution, 532 by a median sternotomy (E group) and 83 by a J-shaped ministernotomy (M group). RESULTS: No significant differences were found between the E and M groups in terms of age (69.27 [9.31] years vs 69.40 [10.24] years, respectively), logistic EuroSCORE (6.27 [2.91] vs 5.64 [2.17], respectively), size of implanted valve prosthesis (21.94 [2.04] mm vs 21.79 [2.01] mm, respectively), or the incidence of diabetes, hypercholesterolemia, high blood pressure, or chronic obstructive pulmonary disease. Mean cardiopulmonary bypass time was 102.90 (41.68) min for the E group vs 81.37 (25.41) min for the M group (P<.001). Mean cross-clamp time was 77.31 (29.20) min vs 63.45 (17.71) min for the S and M groups, respectively (P<.001). Mortality in the E group was 4.88% (26). There were no deaths in the M group (P<.05). The E group was associated with longer intensive care unit and hospital stays: 4.17 (5.23) days vs 3.22 (2.01) days (P=.045) and 9.58 (7.66) days vs 7.27 (3.83) days (P<.001), respectively. E group patients had more postoperative respiratory complications (42 [8%] vs 1 [1.2%]; P<.05). There were no differences when postoperative hemodynamic, neurologic, and renal complications, systemic infection, and wound infection were analyzed. CONCLUSIONS: In terms of morbidity, mortality, and operative times, outcomes after minimally invasive surgery for aortic valve replacement are at least comparable to those achieved with median sternotomy. The length of the hospital stay was reduced by minimally invasive surgery in our single-institution experience. The retrospective nature of this study warrants further randomized prospective trials to validate our results.

Resultados a corto y mediano plazo del tratamiento de la obstrucción al tracto de salida del ventrículo izquierdo mediante miectomía videoasistida / Video assisted myectomy for relief of left ventricular tract obstruction in patients with Obstructive Hypertrophic Cardiomyopathy

Objetivo: Describir nuestra experiencia y evaluar los resultados a corto y mediano plazo de la miecto-mía videoasistida en el tratamiento de la obstrucción del tracto de salida del ventrículo izquierdo (OTSVI) en pacientes con miocardiopatía hipertrófica. Materiales y métodos: 52 pacientes con edad media de 56,2 (rango 12 - 83) y Euroscore de riesgo de 4,1 +/- 1,92 con diagnóstico de OTSVI fueron intervenidos de manera consecutiva en un mismo centro mediante miectomía videoasistida. Se realizó seguimiento clínico y ecocardiográfico con controles al mes y al año del postoperatorio. Resultados: Entre las patologías asociadas encontramos 11 pacientes con valvulopatía aórtica, 2 con valvulopatía mitral, 3 con cardiopatía isquémica, 1 con aneurisma de aorta ascendente y 1 con foramen oval permeable resueltos en el mismo acto quirúrgico. La mortalidad hospitalaria global fue de 5,8 por ciento (3 pacientes). En el momento de la intervención, 8 (15,4 por ciento) se encontraban en clase funcional II de la NYHA, 42 (80,8 por ciento) en clase III y 2 (3,8 por ciento) en clase IV. El gradiente máximo subaórtico disminuyó de 80,7 mmHg +/- 29,43 en el preoperatorio a 19,0 mmHg +/- 15,57 (p<0,001) en el postoperatorio inmediato, manteniéndose en 14,6 mmHg +/- 8,88 al mes (p<0,001 en relación al preoperatorio) y al año en 13,9 mmHg +/- 7,69 (p<0,001 en relación al preoperatorio). Además, se registró una disminución del grosor del tabique interventricular en diástole de 19,4 mm +/- 3,78 en el preoperatorio a 12,9 mm +/- 2,35 (p<0,001) en el postoperatorio. Todos los pacientes se encontraban en clase funcional I-II al final del seguimiento. Conclusión: Los resultados demuestran que la miectomía videoasistida es un tratamiento seguro para la OTSVI con el que se obtienen resultados favorables a corto y mediano plazo, tanto en parámetros clínicos, como ecocardiográficos.

Aim: To report a clinical experience and to evaluate early and mid term results of video assisted myec-tomy for relief of left ventricular tract obstruction (LVOTO) in patients with Obstructive Hypertrophic Cardiomyopathy. Methods: 52 patients with Obstructive Car-diomyopathy and a mean age 56.2 years (12 - 83) carrying a Euro score risk of 4.1 +/- (SD 1.92), were consecutively operated on in a single center. Relief of LVOTO was performed with video assisted myec-tomy. Clinical and echocardiographic follow up to 1 year postoperatively was carried out. Results: Apart from the Obstructive Cardiomyo-pathy, 11 patients had aortic valve disease, 2 mitral valve disease, 3 ischemic heart disease, 1 an ascending aortic aneurysm and 1 a patent foramen ovale. All these lesions were surgically repaired in the same surgical act. In hospital mortality was 5.8 percent (3 patients). Pre-operatively 15.4 percent of patients were in NYHA Class II, 80.8 per cent in Class III and 3.8 percent in Class IV. After surgery peak sub aortic gradient decreased from 80.7+/-29.43mmHg to 19.0 +/- 15.57 (p<0.001). Corresponding values were 14.6 +/- 8.88 at 1month and 13.9 +/- 7.69 at 1 year post operatively. Interven-tricular septal thickness in diastole decreased from 19.4 +/- 3.78 mm to 12.9 +/- 2.35 mm after surgery (p<0.001). All patients were Class I or II at the end of follow up. Conclusion: Video assisted myectomy is safe and effective for relief of LVOTO in patients with hypertrophic cardiomyopathy. Good results are maintained one year after surgery.

Stroke after coronary artery bypass grafting: preoperative predictive accuracies of CHADS2 and CHA2DS2VASc stroke risk stratification schemes.

OBJECTIVE: Neurologic events after coronary artery bypass grafting are an infrequent but devastating complication. This study analyzed the preoperative predictive abilities of the CHADS(2) and CHA(2)DS(2)VASc stroke scores in patients undergoing isolated coronary artery bypass grafting. METHODS: Included in the study were 2910 patients who underwent isolated coronary artery bypass grafting during a 19-year period. CHADS(2) and CHA(2)DS(2)VASc scores were computed for all patients, and outcomes were evaluated in terms of perioperative stroke and compared with 2 specific models for predicting surgical coronary artery bypass grafting stroke (Northern New England Cardiovascular Disease Study Group and Multicenter Study of Perioperative Ischemia Research Group). Perioperative stroke discrimination was quantified by computing the area under the receiver operating characteristic curve. RESULTS: Overall, 62 (2.1%) had perioperative strokes. Areas under the curve were 0.71 (95% confidence interval, 0.64-0.78) for CHADS(2), 0.72 (95% confidence interval, 0.65-0.79) for CHA(2)DS(2)VASc, 0.69 (95% confidence interval, 0.61-0.76) for Northern New England Cardiovascular Disease Study Group, and 0.73 (95% confidence interval, 0.67-0.80) for Multicenter Study of Perioperative Ischemia Research Group scores. Northern New England Cardiovascular Disease Study Group and CHA(2)DS(2)VASc scores were better at discriminating patients with particularly low or high risk of stroke. CONCLUSIONS: CHADS(2) and CHA(2)DS(2)VASc scores predicted perioperative coronary artery bypass grafting strokes with discriminatory abilities similar to those of specific predictive surgical coronary artery bypass grafting stroke models. All schemes tested showed similar limitations in discriminating patients with high postoperative stroke risk, with a high proportion being classified as having intermediate stroke risk.

Factors for development of late significant tricuspid regurgitation after mitral valve replacement: the impact of subvalvular preservation.

OBJECTIVE: Development of late significant tricuspid regurgitation (TR) after successful mitral valve replacement (MVR) is not infrequent. The impact of different aetiologies or diverse surgical procedures has not been adequately investigated. We studied the influence of subvalvular preservation techniques during MVR on the incidence of late TR. METHODS: A total of 801 patients with grade ≤ 2+/4+ preoperative TR underwent MVR without associated tricuspid procedures from January 1994 to August 2008. In 595 patients, only posterior mitral leaflet preservation was performed (group A). In the remaining 206 patients, both anterior and posterior leaflets were retained (group B). Postoperative development of significant TR was defined as a TR increase by more than one grade from preoperative or final TR grade ≥ 3+/4+ at follow-up. RESULTS: The global incidence of postoperative significant TR was 8.6%, with higher incidence in females (9.4% vs 6.7%, p=0.12), rheumatic disease (9.7% vs 6.5%, p=0.07), patients with previous AF (11.8% vs 3.8%, p<0.001) and, especially, in group A (10.8% vs 2.4%, p<0.001). The Maze procedure was protective in patients with AF (the incidence with and without associated Maze was 6.7% vs 13.2%, p=0.04). Preoperative left-atrial diameters were higher in patients with postoperative development of TR (56 ± 9 mm vs 51 ± 12 mm, p=0.01). Group A (p=0.04) and preoperative atrial fibrillation (p=0.001) were significant predictors of late postoperative TR. Late functional TR decreased free survival from chronic heart failure. CONCLUSIONS: Several clinical and operative factors are associated with the development of significant TR after MVR. Although early surgical intervention for TR may be recommended in selected patients, complete subvalvular preservation of the mitral valve and routine surgical ablation of atrial fibrillation can significantly reduce its incidence.

Esophagus histological analysis after hyperthermia-induced injury: implications for cardiac ablation.

PURPOSE: To evaluate and numerically score histological alterations observed in the acute phase in the esophagus after being exposed to a hyperthermic dosage and subsequently to correlate the scores obtained with the hyperthermic treatment parameters (i.e. temperature (T) and time (t)). MATERIAL AND METHODS: Esophagus samples obtained from New Zealand white rabbits were immersed in a temperature-controlled saline bath at 40, 50, 60 and 70 degrees C for 30, 60 and 90 s. Samples were then processed for histological analysis (Masson Trichrome technique), and evaluated by searching for objective heat-damage signs. A numerical value was assigned to each sample for each finding. RESULTS: In general, all the layers were affected by the treatment, however, the greatest alterations were found in the epithelium and deeper muscular layers (circular and longitudinal). We found no damage (i.e. no differences to control) in all of the samples treated at 40 degrees C, and severe damage in treatments at 60 and 70 degrees C, regardless of exposure time. On the other hand, samples treated at 50 degrees C did show different results related to time: no damage for 30 s, light damage for 60 s, and moderate damage for 90 s. We assigned a score value to each hyperthermic dosage, and obtained the fitted equation based on a logarithmic transformation of the Arrhenius equation: Score = 130.7 - 40,851/(T + 273) + log t, (R(2) = 0.9326, P < 0.0001). CONCLUSIONS: Hyperthermic treatment mainly affects the epithelium and deeper muscular layers. The results suggest a damage threshold of 50 degrees C for treatments of 30-90 s. The proposed scoring system provides a good fit with the hyperthermic parameters.

Surgery for atrial fibrillation in patients with mitral valve disease: results at five years from the International Registry of Atrial Fibrillation Surgery.

OBJECTIVES: We sought to assess the clinical and survival benefit of atrial fibrillation surgery in patients submitted to mitral valve surgery after stabilization of postoperative rhythm at 1 year. METHODS: One thousand seven hundred twenty-three patients were enrolled. Patients with follow-up of longer than 1 year (n = 972) were divided into 3 groups according to surface electrocardiographic rhythm during follow-up visits: stable sinus rhythm, stable atrial fibrillation, and intermittent rhythms. Adverse cardiac event incidence and predictors of long-term outcome were compared among the 3 groups. RESULTS: In-hospital mortality was 2.6%. Risk factors for mortality were the cut-and-sew technique (odds ratio, 8.92; 95% confidence interval, 1.71-46.50; P = .009) and isolated left atrial procedure (odds ratio, 0.16; 95% confidence interval, 0.04-0.56; P = .004). At 1 year, 63.4% patients were in stable sinus rhythm. Stable sinus rhythm was found to be associated with early and late survival (P = .01, log-rank analysis). Multivariate binary logistic regression analysis found that left atrial dimension (odds ratio, 0.97; 95% confidence interval, 0.96-0.99; P = .005) and concomitant coronary revascularization (odds ratio, 0.48; 95% confidence interval, 0.25-0.92; P = .027) were independent predictors of stable sinus rhythm at 1 year after surgical intervention. At 48 months' follow-up, predictors for stable sinus rhythm were biatrial surgical approach and absence of preoperative permanent atrial fibrillation (odds ratio, 3.56; 95% confidence interval, 1.62-7.83; P < .002). Left atrial size (each millimeter) has a borderline statistical significance (odds ratio, 0.97; 95% confidence interval, 0.93-1.00; P = .065). Thromboembolic events were found to be associated with absence of stable sinus rhythm (P = .010, log-rank analysis). CONCLUSIONS: The achievement of stable sinus rhythm is a predictor of better survival and lower incidence of thromboembolic events. Predictors of stable sinus rhythm were smaller dimensions of the left atrium, biatrial approach, absence of preoperative permanent atrial fibrillation, and absence of concomitant coronary artery bypass grafting.

Restoring sinus rhythm in patients with previous pacemaker implantation submitted to cardiac surgery and concomitant surgical ablation of atrial fibrillation.

OBJECTIVE: Some patients submitted to cardiac surgery have concomitant atrial fibrillation and a previously implanted pacemaker. Because it is unknown if there is any potential for these patients to reassume a regular rate sinus rhythm after ablation of atrial fibrillation, we reviewed the results of all patients with pacemaker enrolled in the Registry of Atrial Fibrillation. MATERIALS: Thirty-six patients were included in this study. Twenty-six had valve disease, seven had coronary disease and three had congenital heart disease. They were submitted concomitantly to ablation of atrial fibrillation using biatrial approaches (seven patients), left sided (27), or right sided (three patients). Thirty-three hospital survivors had a mean follow-up of 18 months, and a maximum of 25 months. RESULTS: At 1 year (n=21), patients' rhythm was sinus non-pacing dependent (52%), sinus pacing-dependent (14%), and atrial fibrillation (14%). At 2 years (n=14), patients' rhythm was sinus non-pacing dependent (57%) and atrial fibrillation (43%). The only factor that may have had impact on the recovery of sinus rhythm at 1 year was the small size of the left atrium (p=0.05). CONCLUSIONS: We conclude that in a significant number of patients, having a pacemaker before surgery does not preclude sinus rhythm recovery after a cardiac operation and ablation for concomitant atrial fibrillation.

Assessment of hyperbolic heat transfer equation in theoretical modeling for radiofrequency heating techniques.

Theoretical modeling is a technique widely used to study the electrical-thermal performance of different surgical procedures based on tissue heating by use of radiofrequency (RF) currents. Most models employ a parabolic heat transfer equation (PHTE) based on Fourier's theory, which assumes an infinite propagation speed of thermal energy. We recently proposed a one-dimensional model in which the electrical-thermal coupled problem was analytically solved by using a hyperbolic heat transfer equation (HHTE), i.e. by considering a non zero thermal relaxation time. In this study, we particularized this solution to three typical examples of RF heating of biological tissues: heating of the cornea for refractive surgery, cardiac ablation for eliminating arrhythmias, and hepatic ablation for destroying tumors. A comparison was made of the PHTE and HHTE solutions. The differences between their temperature profiles were found to be higher for lower times and shorter distances from the electrode surface. Our results therefore suggest that HHTE should be considered for RF heating of the cornea (which requires very small electrodes and a heating time of 0.6 s), and for rapid ablations in cardiac tissue (less than 30 s).