Left atrial remodelling in mitral regurgitation--methodologic approach, physiological determinants, and outcome implications: a prospective quantitative Doppler-echocardiographic and electron beam-computed tomographic study.

AIMS: To define accurate and normal range of echocardiographic left atrial (LA) volume measurement and to assess the prevalence, determinants, and outcome implications of LA enlargement in mitral regurgitation (MR). METHODS AND RESULTS: We prospectively compared LA volume obtained simultaneously by electron beam-computed tomography (EBCT) and by four echocardiographic methods in 33 test patients. Accurate echocardiographic LA volume measurements were obtained only by biplane area-length method with vertical longitudinal-length (r = 0.95, P < 0.0001; 145 +/- 57 vs. 143 +/- 55 mL, P = 0.57). Using this method, the normal range in 100 normal subjects, the physiological determinants and outcome implications of LA enlargement in 320 patients with organic MR were analysed. In normal subjects, indexed to body surface area, LA index (27 +/- 6 mL/m(2)) was not influenced by age or gender and values > or = 40 mL/m(2) were beyond the upper limit of normal. In MR, the most powerful determinants of LA enlargement were higher regurgitant volume (RVol) and atrial fibrillation (AF) (P < 0.0001), followed by older age, female gender, higher left ventricular end-systolic volume, and mass (all P < 0.001). After diagnosis in sinus rhythm, LA index > or = 40 mL/m(2) predicted superiorly and independently to LA diameter the occurrence of AF [adjusted RR 1.48 (1.06-2.16), P < 0.01] and the combined endpoint of death or need for mitral surgery [adjusted RR 1.61 (1.3-2.0), P < 0.0001]. CONCLUSION: LA remodelling can be accurately assessed by echocardiography and LA index > or = 40 mL/m(2) is beyond the normal range. In organic MR, higher LA index is the combined result of multiple physiological effects, provides independent prognostic information, and therefore should be part of a comprehensive echocardiographic examination.     

Favorable effect of balloon mitral valvuloplasty on the incidence of atrial fibrillation in patients with severe mitral stenosis.

BACKGROUND: The long-term effect of balloon mitral valvuloplasty (BMV) on the incidence of atrial fibrillation (AF) in patients with severe mitral stenosis (MS) remains undetermined. AIMS: To assess the effect of successful BMV on the incidence of chronic AF in patients with severe MS, compare the results with historical controls, and identify factors associated with AF in such patients. METHODS: Retrospective analysis of 382 consecutive patients with severe MS and in sinus rhythm (SR) who underwent successful BMV (post procedure mitral valve area (MVA) > or =1.5 cm(2), mitral regurgitation (MR) < or =2/4) at our hospital and followed-up for 1-15.6 (mean 5.6 +/- 3.9) years with clinical and echocardiographic examination. RESULTS: Thirty-four (8.9%) patients developed AF at follow-up (group A) and 348 patients (group B) remained in SR. At baseline, and in comparison with group B, patients who developed AF (group A) were older, had higher mitral echo score but equal MVA and left atrial (LA) size. The postprocedure MVA was smaller in group A (1.7 +/- 0.3 cm(2)) than in group B (2.0 +/- 0.2 cm(2;) P = 0.002). At follow-up, and in comparison to group B, group A had smaller MVA (1.5 +/- 0.4 cm(2) vs 1.8 +/- 0.4 cm(2) P <0.0001), larger LA dimension (49.4 +/- 6.5 vs 42 +/- 6.5 mm; P <0.0001) and higher restenosis rate (35% vs 14%; P = 0.001). Multivariate logistic regression analysis identified age at follow-up (P < 0.0001), LA size at follow-up (P = 0.004), and MVA at follow-up (P = 0.006) as predictors of AF. CONCLUSIONS: This study demonstrated favorable effect of BMV on the incidence of AF (8.9%) in patients with severe MS in comparison with reported series (29%) of patients with severe MS with similar baseline characteristics who were not submitted to any intervention. The predictors of AF were age, larger LA, and smaller MVA, at follow-up.     

Impact of atrial fibrillation on tricuspid and mitral annular dilatation and valvular regurgitation.

To investigate the effects of atrial fibrillation (AF) on the mitral and tricuspid valves, the corresponding annular dilatation and valvular regurgitation were compared with 2-dimensional and Doppler echocardiography in 31 consecutive patients with lone AF and 28 normal controls. Mid-systolic mitral and tricuspid annular areas were measured from 2 diameters in 2 orthogonal apical echocardiograms. Percent (%) mitral regurgitant (MR) or tricuspid regurgitant (TR) jet area to the left or right atrial area was evaluated and % MR or TR jet area >20% was considered moderate or significant. Both the mitral and tricuspid annular areas in patients with lone AF were significantly larger compared with the controls (mitral: 9.5 +/- 1.2 vs 6.6 +/- 0.9 cm2, lone AF vs control, p < 0.01) (tricuspid: 12.0 +/- 2.0 vs 7.5 +/- 0.9 cm2, p < 0.01). The % increase in the annular area relative to the mean normal value was significantly greater in the tricuspid valve (44 +/- 18 vs 60 +/- 28%, p < 0.01). Moderate or severe MR was not observed and the incidence of moderate or severe valve regurgitation (% jet area >20%) was significantly higher in the tricuspid valve (0/31 vs 11/31, MR vs TR, p < 0.01) in patients with lone AF. The % TR jet area showed significant correlation with tricuspid annular area (r2 = 0.65, p < 0.001). Lone AF is associated with annular dilatation of both mitral and tricuspid valves, but the annular dilatation and valvular regurgitation are significantly greater in the tricuspid valve.     

Factors determining early left atrial reverse remodeling after mitral valve surgery

This study aimed to investigate the factors determining early left atrial (LA) reverse remodeling after mitral valve (MV) surgery. The left atrium is frequently dilated in patients with mitral stenosis (MS) or mitral regurgitation (MR). MV surgery usually results in LA volume reduction. However, the factors associated with LA reverse remodeling after MV surgery are not clearly defined. One hundred thirty-eight patients (51 men, 87 women; mean age, 53 years) underwent transthoracic echocardiography before and after MV surgery. Maximal LA volume was measured using the prolate ellipsoid model. The percentage of LA volume change was calculated. The patients were grouped according to age (<50 vs >or=50 years), predominant lesion (pure MR vs some degree of MS), type of surgery (MV repair vs MV replacement), and preoperative rhythm (sinus rhythm vs atrial fibrillation). LA volume decreased from 147+/-93 to 103+/-43 ml (p<0.001) after surgery. LA reverse remodeling was more prominent in patients who were <50 years old (percentage of LA volume change -31.2+/-17.4 vs -18.4+/-19.2, p<0.001), had pure MR (percentage of LA volume change -30.4+/-18.6 vs -17.3+/-18.2, p<0.001), and had a preoperative sinus rhythm (percentage of LA volume change -28.5+/-17.7 vs -20.5+/-20.0, p=0.019). In conclusion, on stepwise multiple regression analysis, preoperative LA volume, predominant lesion, age, and cardiac rhythm were significant predictors of LA reverse remodeling. A larger preoperative LA volume, MR rather than MS, younger age at the time of surgery, and sinus rhythm were important predictors of LA reverse remodeling after MV surgery.     

Prognostic predictors of sinus rhythm control by amiodarone and electrical cardioversion in patients undergoing percutaneous transluminal mitral valvuloplasty for rheumatic atrial fibrillation.

BACKGROUND: Conversion to sinus rhythm (SR) is rarely attempted in patients with rheumatic atrial fibrillation (AF) because the length of AF duration and the dilation of left atrium (LA) make maintenance of SR difficult. In this study, predictors of the successful maintenance of SR with amiodarone and electrical cardioversion in rheumatic AF patients receiving percutaneous transluminal mitral valvuloplasty (PTMV) were identified. METHODS AND RESULTS: This study included 23 consecutive patients undergoing PTMV for rheumatic AF (6 men, 53+/-11 years; AF duration 25 +/-24 months; LA diameter 44+/-6 mm; mitral valve area (MV) 1.1+/-0.2 cm(2)). Electrical cardioversion was required for the successful conversion to SR in all patients regardless of whether they had received amiodarone (400 mg/day) 2 months before PTMV (n=8) or 2 months after (n=15). After cardioversion, all patients received amiodarone 200 mg/day. With a follow-up period of 35+/-8 months, 14 patients (61%) remained in SR. A greater reduction in LA size (-4+/-3 mm vs 1+/-1 mm; p=0.004) and an greater increase in MV area (0.8+/-0.4 cm(2) vs 0.5+/-0.2 cm(2); p=0.01) by PTMV, not AF duration, were found to be the independent predictors for patients with successful maintenance of SR as compared with patients with recurrence of AF. CONCLUSION: In rheumatic AF patients receiving PTMV, the successful maintenance of SR with amiodarone and electrical cardioversion can be predicted by the degree to which LA size is reduced and MV area is increased.     

Acute and chronic reduction of functional mitral regurgitation in experimental heart failure by percutaneous mitral annuloplasty

OBJECTIVES: We sought to determine acute and chronic efficacy of a percutaneous mitral annuloplasty (PMA) device in experimental heart failure (HF). Further, we evaluated the potential for adverse effects on left ventricular (LV) function and coronary perfusion. BACKGROUND: Reduction of mitral annular dimension with a PMA device in the coronary sinus may reduce functional mitral regurgitation (MR) in advanced HF. METHODS: Study 1: a PMA device was placed acutely in anesthetized open-chest dogs with rapid pacing-induced HF (n = 6) instrumented for pressure volume analysis. Study 2: in 12 anesthetized dogs with HF, fluoroscopic-guided PMA was performed, and dogs were followed for four weeks with continuing rapid pacing. RESULTS: Study 1: percutaneous mitral annuloplasty reduced annular dimension and severity of MR at baseline and with phenylephrine infusion to increase afterload (MR jet/left atrial [LA] area 26 +/- 1% to 7 +/- 2%, p < 0.05). Pressure volume analysis demonstrated no acute impairment of LV function. Study 2: no device was placed in two dogs because of prototype size limitations. Attempted PMA impaired coronary flow in three dogs. Percutaneous mitral annuloplasty (n = 7) acutely reduced MR (MR jet/LA area 43 +/- 4% to 8 +/- 5%, p < 0.0001), regurgitant volume (14.7 +/- 2.1 ml to 3.1 +/- 0.5 ml, p < 0.05), effective regurgitant orifice area (0.130 +/- 0.010 cm(2) to 0.040 +/- 0.003 cm(2), p < 0.05), and angiographic MR grade (2.8 +/- 0.3 device to 1.0 +/- 0.3 device, p < 0.001). In the conscious state, MR was reduced at four weeks after PMA (MR jet/LA area 33 +/- 3% HF baseline vs. 11 +/- 4% four weeks after device, p < 0.05) CONCLUSIONS: Percutaneous mitral annuloplasty results in acute and chronic reduction of functional MR in experimental HF.     

Comparison of left atrial volume and function after linear ablation and after cardioversion for chronic atrial fibrillation

Several techniques for treatment of atrial fibrillation (AF) have been developed, including the direct placement of radiofrequency for lesions at open heart surgery. Detailed evaluation of left atrial (LA) function has not been performed after these procedures and has not been compared in patients with chronic AF. We compared the atrial function of patients with sustained sinus rhythm (SR) after linear ablation with a group who underwent direct-current cardioversion and a group of normal controls to investigate the measurable deleterious effects, if any, on atrial function after the surgical procedure. Twenty-one consecutive patients who had maintained SR for >6 months after a linear radiofrequency ablation (LRFA) procedure were studied. As control subjects, we examined 33 patients with chronic AF successfully restored to SR by cardioversion who maintained SR for >6 months and 42 age-matched normal subjects. LA function was decreased in both the LRFA and cardioverted AF groups compared with normal controls. The parameters of LA function, atrial fraction, LA ejection fraction, and the A' velocity were lowest in the LRFA group, intermediate in the cardioverted AF group, and highest in the normal controls (LA function: 15.8 +/- 10%, 26 +/- 10%, 33 +/- 7%; p = 0.0001; LA ejection fraction: 31 +13%, 41 +/- 12%, 51 +/- 9%; p = 0.0001; A' velocity: 4.2 +/- 1.4, 7.6 +/- 2.2, 9.5 +/- 1.9 cm/s; p = 0.0001). LA volumes were increased in the LRFA and cardioverted AF groups compared with normals (62.8 +/- 22 vs 70.6 +/- 17 vs 38.7 +/- 9.8 ml; p = 0.0001). Thus, although LA function is restored and maintained after LRFA has been performed during open heart surgery, LRFA use is associated with a measurable decrease in LA function over and above that found after conventional cardioversion.     

Atrial structural remodelling and restoration of atrial contraction after linear ablation for atrial fibrillation.

AIMS: We determined late atrial function following a surgical linear endocardial radiofrequency (RF) ablation procedure that aimed to restore and maintain sinus rhythm (SR) in atrial fibrillation (AF). We tested the hypothesis that successful restoration of SR is accompanied by measurable mechanical atrial function that is at normal or near normal levels. METHODS: Forty-seven patients who underwent the surgical RF procedure at least 6 months previously (median 2.86 years; range: 0.6-4.2 years) were studied using an array of echocardiographic variables. Two patient groups (SR restored [RF-SR], persistent AF [RF-AF]) and an age matched control group were studied. Among the echocardiographic variables measured were left atrial (LA) size and volume, LA active fractional emptying and mitral annular displacement corresponding to atrial contraction (A' velocity) by Doppler tissue imaging. RESULTS: At long term follow up 29/47of patients who underwent the RF procedure were in SR with atrial contraction present echocardiographically. Of the patients initially restored to SR, the proportion remaining in SR at 3 years was 79% (SE 9%). The atrial-emptying fraction was reduced in comparison to that seen in normal controls (27+/-14% vs 46+/-10%). The A' velocity was decreased in the surgical RF cohort vs controls (4.4+/-1.3 vs 9.7+/-1.7cm/s; P=0.0001). Despite LA size preoperatively being similar in both surgical groups, atrial size decreased in those in whom SR was restored (48.6+/-7.6 vs 44.8+/-4.7mm; P=0.0001) but increased in those in whom AF persisted (48.2+/-8.1mm vs 52.3+/-7.8mm; P=0.0001). CONCLUSION: The radial pattern of linear radiofrequency ablation used in the present study resulted in restoration of SR and atrial function. Procedural success was independent of preoperative atrial size. Restoration of SR results in 'reverse' atrial remodelling and improved atrial function. However atrial function remains modestly impaired, either due to the ablation lesions or pre-existing atrial disease.     

Pre-operative atrial fibrillation as the key determinant of outcome of mitral valve repair for degenerative mitral regurgitation.

AIMS: To examine the impact of pre-operative atrial fibrillation (AF) on the outcome of mitral valve repair (MVR) for degenerative mitral regurgitation (MR). METHODS AND RESULTS: Among 392 patients with moderate to severe MR who underwent MVR between 1991 and 2002, 283 patients with isolated degenerative MR were followed for 4.7+/-3.3 years. Of 27 deaths, nine were due to cardioembolic events and four were due to left ventricular (LV) dysfunction. When compared with patients with pre-operative AF, those with sinus rhythm (SR) had better survival (96+/-2.1 vs. 87+/-3.2% at 5 years, P=0.002) and higher cardiac event-free rates (96+/-2.0 vs. 75+/-4.4% at 5 years, P<0.001). In patients with pre-operative SR, observed and expected survival were similar (P=0.811). Cox multivariable regression analysis confirmed AF [P=0.027, adjusted hazard ratio (AHR) 2.9] and age as independently predictive of survival, and AF (P=0.002, AHR 3.1), New York Heart Association Class, and LV fractional shortening as independently predictive of cardiac event. CONCLUSION: Death due to LV dysfunction was not frequent and cardioembolic events due to AF were the leading cause for cardiac death. Pre-operative AF became a strong independent predictor of survival and morbidity. Patients with pre-operative SR had excellent prognosis. The benefits of preventing cardioembolic events due to AF validate the indication of MVR for patients with high risk for AF.     

Effect of radiofrequency catheter ablation for atrial fibrillation on left atrial cavity size

Left atrial (LA) remodeling is associated with atrial fibrillation (AF). Radiofrequency catheter ablation offers a good treatment option for AF, with reasonable long-term results. The purpose of the present study was to assess whether LA reverse remodeling occurs after successful catheter ablation. Fifty-seven consecutive patients (45 men; age 53 +/- 8 years) with symptomatic drug-refractory AF were treated with radiofrequency catheter ablation. The patients were divided into 2 groups on the basis of AF recurrence as determined by Holter monitoring and 12-lead electrocardiographic findings at 6 weeks and 3 months of follow-up (sinus rhythm [SR] group, no recurrence; AF group, AF recurrence). At baseline and 3 months of follow-up, 2-dimensional echocardiography was performed to assess LA size and dimensions. Furthermore, LA volumes were measured at end-systole and end-diastole. After 3 months, 39 of 57 patients (68%) maintained SR. At 3 months of follow-up, the LA anteroposterior diameter showed a significant reduction in the SR group (4.5+/- 0.3 vs 4.2 +/- 0.2 cm, p <0.01), and an additional increase was observed in the AF group (4.5+/- 0.3 vs 4.8 +/- 0.3 cm, p <0.05). Furthermore, the LA end-systolic and end-diastolic volumes decreased significantly in the SR group from baseline to follow-up (59 +/- 12 vs 50 +/- 11 ml, p <0.01, and 37 +/- 9 vs 31 +/- 7 ml, p <0.01, respectively). However, a tendency toward an increase in LA volumes was observed in the AF group. In conclusion, the results of this study have demonstrated that LA reverse remodeling occurs after successful radiofrequency catheter ablation for AF.     

Atrial fibrillation complicating the course of degenerative mitral regurgitation: determinants and long-term outcome

OBJECTIVES: The study was done to define the incidence, determinants and prognostic implications of onset of atrial fibrillation (AF) during follow-up of mitral regurgitation (MR) initially in sinus rhythm. BACKGROUND: The rates and clinical implications of AF in MR are undefined. METHODS: We analyzed the occurrence of AF under conservative management in two populations of patients with degenerative MR in sinus rhythm at diagnosis: 1) 360 patients (65 +/- 13 years, 74% men) with MR due to flail leaflets; and 2) 89 residents of Olmsted County, Minnesota (67 +/- 17 years, 56% men) with grade 3 or 4 MR due to simple mitral valve prolapse (MVP) diagnosed echocardiographically. RESULTS: In patients with MR due to flail leaflets, AF rates at 5 and 10 years were 18 +/- 3% and 48 +/- 6%, respectively, and the linearized rate was 5.0 +/- 0.7% per year. Development of AF during follow-up was independently associated with high risk of cardiac death or heart failure (adjusted risk ratio 2.23, p = 0.025). The AF rate at 10 years was higher in patients >or=65 years (75 +/- 10% vs. 24 +/- 6%, p < 0.0001) and in those with baseline left atrial (LA) dimension >or=50 mm (67 +/- 8% vs. 37 +/- 9%, p < 0.001). In multivariate analysis, independent baseline predictors of AF were age and LA diameter (both p < 0.01). In patients with MR due to MVP, similar rates of AF (41 +/- 7% vs. 44 +/- 6% at nine years, p > 0.50) and predictors of AF (age and LA dimension, both p < 0.006) were noted. CONCLUSIONS: In patients with degenerative MR in sinus rhythm at diagnosis, the incidence of AF occurring under conservative management is high and similar whether the cause of MR is flail leaflet or simple MVP. After onset of AF, an increased cardiac mortality and morbidity are both observed under conservative management. The risk of AF increases with advancing age and larger LA dimension. These data suggest that the clinical management of MR should take into account the high incidence, excess risk, and predictors of AF.     

Management of persistent atrial fibrillation following balloon mitral valvotomy: safety and efficacy of low-dose amiodarone

BACKGROUND AND AIM OF THE STUDY: Atrial fibrillation (AF) is the most common sustained cardiac arrhythmia encountered in clinical practice. In developing countries, rheumatic mitral stenosis (MS) is the most frequent underlying condition in patients with AF. Sinus rhythm (SR) is difficult to achieve and maintain in these patients, but would be more easily achieved with reduction of left atrial pressure after successful balloon mitral valvotomy (BMV). METHODS: Eighty-five patients with persistent AF following BMV received amiodarone (600 mg once daily for two weeks, 200 mg daily thereafter). Electrical cardioversion was performed in those with persistent AF (at six and 12 weeks of drug therapy). RESULTS: Among patients, 33 (39%) converted with amiodarone alone. Of 52 patients who underwent cardioversion at six weeks, 41 (79%) converted to SR. Overall, 87% of patients converted to SR. None of the 11 patients with persistent AF could be converted to SR, despite a second attempt with direct current (DC) cardioversion at 12 weeks. Those who converted to SR had significantly shorter AF duration (AFD) (2.7+/-1.1 versus 3.2+/-0.7 years) and smaller left atrial (LA) size (50.0+/-7.7 versus 57.9+/-4.7 mm). Patient age, gender, NYHA class, ejection fraction and post-BMV variables were comparable between the two groups. Successful maintenance of SR was possible in 61/74 (82%) patients at a mean follow up of 30.6+/-7.1 months (range: 16-43 months). Again, mean AFD was shorter (1.8+/-0.6 versus 3.0+/-0.7 years) and LA size smaller (48.9+/-7.5 versus 54.7+/-6.9 mm) among those who maintained SR. However, even in patients with AFD > or =2 years, successful conversion and maintenance of SR was possible in 74% and 62% of patients, respectively. Among patients with LA size > or =60 mm (n = 16), the corresponding value were 84% and 77%, respectively. On multivariate analysis, only AFD was a predictor of acute and long-term success. The probability of SR remaining in those with AFD <2 years at 21, 30 and 43 months was 96%, 95% and 94.6%, respectively, while for those with AFD > or =2 years these values were 62%, 48% and 40%. CONCLUSION: Low-dose amiodarone was safe and effective in restoring and maintaining SR in patients with AF and rheumatic heart disease.     

Comparison of left atrial volumes and function by real-time three-dimensional echocardiography in patients having catheter ablation for atrial fibrillation with persistence of sinus rhythm versus recurrent atrial fibrillation three months later

Real-time 3-dimensional echocardiography (RT3DE) can provide a unique combination of accurate left atrial (LA) volume quantification and rapid, automatic assessment of LA function. The aim of the study was to evaluate the changes in LA volumes and function in patients with atrial fibrillation (AF) undergoing radiofrequency catheter ablation (RFCA) using RT3DE; 57 consecutive patients referred for RFCA were studied. Paroxysmal AF was present in 43 patients (75%) and persistent AF in 14 (25%). After a mean follow-up of 7.9 +/- 2.7 months, patients were divided into 2 groups: successful RFCA (SR group) and recurrence of AF (AF group). RT3DE was performed before, within 3 days, and 3 months after RFCA to assess LA volumes (maximum, minimum, and preA) and LA functions (passive, active, and reservoir). A total of 38 patients (67%) had successful RFCA (SR group). Immediately after RFCA, no significant changes in LA volumes and function were observed. After 3 months, a significant reduction in LA volumes (maximum: 26 +/- 8 to 23 +/- 7 ml/m(2), p <0.01) was noted only in the SR group, with a significant improvement in LA active (22 +/- 8% to 33 +/- 9%, p <0.01) and reservoir functions (116 +/- 45% to 152 +/- 54%, p <0.01). Conversely, the AF group showed a trend towards a deterioration of LA volumes and function. In conclusion, in patients who maintain sinus rhythm after RFCA, a significant reverse remodeling and functional improvement of the left atrium is observed using RT3DE.     

A decrease of enlarged left atrium following cardioversion of atrial fibrillation predicts the long-term maintenance of sinus rhythm

BACKGROUND: Although increased left atrial size (LA) has been long regarded as one of the factors negatively influencing the long-term maintenance of sinus rhythm (SR) following cardioversion (CV) of atrial fibrillation (AF), some reports suggested that CV might be effective also in patients with large LA.Aim. We sought to determine the role of LA enlargement in long-term SR maintenance after CV of persistent AF. METHODS: 104 consecutive patients (33 females, 71 males, mean age 60.4+/-7.4 years) were assigned to SR restoration and maintenance with serial antiarrhythmic drugs. Transthoracic echocardiographic (TTE) variables were recorded prior to CV. Generalised additive logistic regression was used to investigate the impact of LA enlargement on the long-term SR maintenance. RESULTS: SR was present in 63.5% of patients after one year of follow-up. Increased LA area >28 cm (RR 1.72; 1.09-2.71; p<0.02) and increased fractional shortening values in ranges between 26-40% (1.2; 1.01-1.44; p<0.05) were significantly associated with SR maintenance after one year. In order to determine the influence of the LA diameter on the probability of SR maintenance, we analysed mean LA(ar) values prior to and after CV. Patients with large LA(ar) (28 cm(2)) presented a significant decrease of LA size (31.45+/-3.07 cm(2) vs 28.94+/-3.81 cm(2); p<0.008) during the first 30 days after SR restoration. In the group of patients with LA(ar) 28 cm(2) we noted decrease in LA size by 2.57+/-3.2 cm(2), whereas in patients with a smaller LA volume this decrease was significantly lower, being 0.47+/-2.9 cm(2) (p<0.004). CONCLUSIONS: LA enlargement does not preclude a favourable outcome after CV of AF. The decrease in LA area occurring during 30 days following CV favours long term SR maintenance.     

Effect of haemodialysis on left atrial mechanical function in patients with chronic renal failure

OBJECTIVE: The aim of this study was to investigate the potential effects of haemodialysis on left atrial (LA) mechanical functions in patients with chronic renal failure. METHODS: Thirty-two patients with chronic renal failure (mean age 42.8 +/- 19.6 years) were included in this study. LA volumes were determined echocardiographically at the time of mitral valve opening (maximal,Vmax), at the onset of atrial systole (p wave at the electrocardiography = Vp) and at the mitral valve closure (minimal, Vmin) according to the biplane area-length method in apical 4-chamber and 2-chamber view. All volumes were corrected to the body surface area, and the following left atrial emptying functions were calculated. LA passive emptying volume = Vmax - Vp, LA passive emptying fraction = LA passive emptying volume/Vmax. Conduit volume = LV stroke volume-(Vmax - Vmin), LA active emptying volume = Vp Vmin. LA active emptying fraction = LA active emptying volume/Vp, LA total emptying volume = (Vmax - Vmin), LA total emptying fraction = LA total emptying volume/Vmax. RESULTS: Mean fluid removal was 1,875 +/- 812 milliliter.There was no difference between in the LA passive emptying volume before and after dialysis (10.83 +/- 7.44 vs. 11.47 +/- 7.73 cm3/m2, p > 0.05). Conduit volume (from 15.30 +/- 10.68 to 10.31 +/- 6.83 cm3/m2, p < 0.05), LA active emptying volume (from 12.61 +/- 6.39 to 9.25 +/- 4.40 cm3/m2, p < 0.005), LA total emptying volume (from 23.44 +/- 8.52 to 20.72 +/- 8.58 cm3/m2, p < 0.05), LA maximal volume (from 39.44 +/- 14.07 to 28.89 +/- 11.80 cm3/m2, p < 0.001), LA minimal volume (from 15.99 +/- 9.70 to 8.17 +/- 4.52 cm3/m2, p < 0.001), and the volume at the onset of atrial systole (from 28.61 +/- 10.36 to 17.42 +/- 7.20 cm3/m2, p < 0.001) decreased significantly after the haemodialysis session, whereas LA passive emptying fraction (from 0.27 +/- 0.14 to 0.38 +/- 0.14%, p < 0.001), LA active emptying fraction (from 0.46 +/- 0.18 to 0.53 +/- 0.17%, p < 0.05), LA total emptying fraction (from 0.61 +/- 0.14 to 0.72 +/- 0.09%, p < 0.001) increased significantly after haemodialysis. CONCLUSION: The results of this study suggest that left atrial mechanical functions improve after haemodialysis in patients with chronic renal failure.     

Left atrial reservoir function as a potent marker for first atrial fibrillation or flutter in persons > or = 65 years of age

The aim of this prospective study was to evaluate the incremental value of left atrial (LA) function for the prediction of risk for first atrial fibrillation (AF) or atrial flutter. Maximum and minimum LA volumes were quantitated by echocardiography in 574 adults (mean age 74 +/- 6 years, 52% men) without a history or evidence of atrial arrhythmia. During a mean follow-up period of 1.9 +/- 1.2 years, 30 subjects (5.2%) developed electrocardiographically confirmed AF or atrial flutter. Subjects with new AF or atrial flutter had lower LA reservoir function, as measured by total LA emptying fraction (38% vs 49%, p <0.0001) and higher maximum LA volumes (47 vs 40 ml/m(2), p = 0.005). An increase in age-adjusted risk for AF or atrial flutter was evident when the cohort was stratified according to medians of LA emptying fraction (< or =49%: hazard ratio 6.5, p = 0.001) and LA volume (> or =38 ml/m(2): hazard ratio 2.0, p = 0.07), with the risk being highest for subjects with concomitant LA emptying fractions < or =49% and LA volume > or =38 ml/m(2) (hazard ratio 9.3, p = 0.003). LA emptying fraction (p = 0.002) was associated with risk for first AF or atrial flutter after adjusting for baseline clinical risk factors for AF or atrial flutter, left ventricular ejection fraction, diastolic function grade, and LA volume. In conclusion, reduced LA reservoir function markedly increases the propensity for first AF or atrial flutter, independent of LA volume, left ventricular function, and clinical risk factors.     

Quantitative assessment of severity of mitral regurgitation by serial echocardiography in a multicenter clinical trial of percutaneous mitral valve repair

The aims of the echocardiographic substudy of this multicenter trial were to evaluate the use of quantitative assessment of mitral regurgitation (MR) severity using serial echocardiography and to assess the efficacy of percutaneous mitral valve repair. Previous surgical repair studies did not use quantitative echocardiographic methods. Results of a percutaneous mitral valve repair clip device in a core echocardiographic laboratory were evaluated. Published parameters for quantifying MR were used in a systematic protocol to qualify patients for study entry and evaluate treatment efficacy at discharge and 6 months after clip repair. Baseline results were presented for 55 patients, and follow-up results, for 49. Ninety-eight percent of required echocardiographic studies were submitted to the core laboratory, and >85% of required measurements were possible. At baseline, mean regurgitant volume was 54.8 +/- 24 ml, regurgitant fraction was 46.9 +/-16.2%, effective regurgitant orifice area was 0.71 +/- 0.40 cm(2), and vena contracta width was 0.66 +/- 0.20 cm. Based on a severity scale of 1 to 4, mean color flow grade was 3.4 +/- 0.7, and mean pulmonary vein flow was 2.8 +/- 1.2. In patients with a clip at 6 months, all measurements of MR severity were significantly decreased versus baseline, with mean regurgitant volume decreased from 50.3 to 27.5 ml (change -22.8 ml; p <0.0001), regurgitant fraction from 44.6% to 28.9% (change -15.7%; p <0.0001), color flow grade from an average of 3.4 to 1.8 (change -1.6; p <0.0001), and pulmonary vein flow from 2.8 to 1.8 (change -1.0; p <0.0018). In conclusion, quantitative assessment of MR is feasible in a multicenter trial, and percutaneous mitral repair with the MitraClip produces a sustained decrease in MR severity to moderate or less for > or =6 months.     

Effects of valve replacement for aortic stenosis on mitral regurgitation

We aimed to prospectively and quantitatively assess the effects of aortic valve replacement (AVR) for aortic stenosis (AS) on mitral regurgitation (MR) and to examine the determinants of the changes in MR. Fifty-two patients with AS scheduled for AVR were included if holosystolic MR not being considered for replacement or repair was detected. MR was quantified using the proximal isovelocity surface area method before and 8 +/- 4 days after surgery. Mitral valvular deformation parameters did not change significantly, but the mitral effective regurgitant orifice (ERO) and regurgitant volume decreased from 11 +/- 6 mm(2) to 8 +/- 6 mm(2) and from 20 +/- 10 ml to 11 +/- 9 ml, respectively (both p <0.0001). Using multiple linear regression analysis, preoperative severity of MR, mitral leaflet coaptation height, and end-diastolic volume decrease were independently associated with postoperative reduction in MR, whereas changes in mitral valve morphology after surgery were not. MR etiology did not predict the reduction in MR. In conclusion, the decrease in MR observed in most patients after AVR is associated with the magnitude of acute left ventricular reverse remodeling. As the reduction in left ventricular systolic pressure contributes to the decrease in regurgitant volume, the preoperative quantitative assessment of MR should best be performed by measurement of the ERO.     

Effect of losartan on degree of mitral regurgitation quantified by echocardiography

The objective of this study was to determine the effect of oral losartan on the degree of mitral regurgitation (MR). The regurgitant volume and effective regurgitant orifice were quantified using 3 methods (flow convergence, quantitative Doppler, and quantitative 2-dimensional echocardiography) in 32 patients (26 men, mean age 67 +/- 14 years) with MR, both at baseline and 4 hours after losartan (50 mg orally). Twenty-eight patients were also reevaluated after 1 month of continued treatment with losartan (50 mg/day). With treatment, systolic blood pressure decreased from 143 +/- 16 to 130 +/- 18 mm Hg and left ventricular end-systolic wall stress from 173 +/- 46 to 156 +/- 44 g/cm2 (both p < 0.001). With treatment, regurgitant volume decreased (from 77 +/- 28 to 64 +/- 26 ml, - 18 +/- 10%; p < 0.001) in direct relation to the effective regurgitant orifice change (from 43 +/- 16 to 37 +/- 15 mm2, -17 +/- 10%; p < 0.001) but without significant change in regurgitant gradient or duration. Wide individual variability in response was observed unrelated to the magnitude of blood pressure changes. Larger reduction in regurgitant volume was observed in patients with a marked decrease in wall stress (r = 0.47, p = 0.01) and higher baseline end-diastolic volume index (r = -0.38, p = 0.03) and regurgitant volume (r = -0.45, p = 0.01). Acute improvements were sustained and unchanged at 1 month (all p > 0.15). Treatment of MR using the angiotensin receptor antagonist losartan produces a significant and sustained decrease in the degree of MR, with decreases in regurgitant volume and effective regurgitant orifice. However, the changes are of modest and variable magnitude.     

Identification of good responders to rhythm control of paroxysmal and persistent atrial fibrillation by transthoracic and transesophageal echocardiography

BACKGROUND: Identification of good responders to rhythm control in the management of atrial fibrillation (AF) is worthwhile in terms of increasing hemodynamic benefit and decreasing the likelihood of unstable anticoagulation even after the Atrial Fibrillation Follow-Up Investigation of Rhythm Management. METHODS: We tested the hypothesis that atrial substrate determines the risk of recurrence on rhythm control both in patients with paroxysmal AF (PAF) and in those with persistent or sustained AF (> or =1 week, SAF). There were 90 consecutive patients (mean age 63 +/- 12 years, 67 males and 23 females) with previous PAF (n = 66) or SAF (n = 24). They were maintained in sinus rhythm successfully for at least 1 month after conversion and then studied by transthoracic and transesophageal echocardiography. All of the patients were followed regularly by determination of symptoms, 12-lead ECG and intermittent Holter recording to determine recurrence of AF after echocardiographic study. RESULTS: After 9.1 +/- 3.8 (range 3-12) months of follow-up, 23 of the 90 (26%) patients had documented recurrence of AF (67 without recurrence). Univariate analysis of demographic characteristics, medications, ECG and echocardiographic parameters revealed that, compared with the group of patients without recurrent AF, the group of those with it included more members of the SAF group (11/27 vs. 13/67, p = 0.039), included more male subjects (22/23 vs. 45/67, p = 0.045), had a larger left atrial volume index (LAVI; 27 +/- 9 vs. 22 +/- 9 ml/m2, p = 0.024) and had lower LA appendage peak emptying velocity (LAAPEV; 42 +/- 15 vs. 55 +/- 22 cm/s, p = 0.01). Multivariate Cox proportional hazards regression analysis adjusted for age, gender and AF group revealed that patients with LAVI <30 ml/m2 and LAAPEV >46 cm/s had the least recurrence of AF (relative risk 0.18, 95% confidence interval 0.06-0.55, vs. with LAVI >30 ml/m2 or LAAPEV <46 cm/s, p = 0.002). Kaplan-Meier probability of freedom from AF recurrence was significantly better when LAVI <30 ml/m2 (log-rank p = 0.02), LAAPEV > 46 cm/s (p = 0.013) or both (p = 0.004). The superiority to predict the rate of sinus rhythm maintenance was the same in the PAF and SAF groups. CONCLUSIONS: Good responders to rhythm control in the PAF and SAF groups share the characteristics of smaller LA volume and better LAA contractile function, emphasizing the critical role of atrial substrate remodeling in recurrence of AF.