Balloon mitral commissurotomy in juvenile rheumatic mitral stenosis: a ten-year clinical and echocardiographic actuarial results

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1 European Heart Journal (2003) 24, Balloon mitral commissurotomy in juvenile rheumatic mitral stenosis: a ten-year clinical and echocardiographic actuarial results H. Gamra*, F. Betbout, K. Ben Hamda, F. Addad, F. Maatouk, Z. Dridi, S. Hammami, M. Abdellaoui, H. Boughanmi, T. Hendiri, M. Ben Farhat Cardiology Department, Fattouma Bourguiba University Hospital, 5000 Monastir, Tunisia Received 31 January 2003; revised 3 April 2003; accepted 18 April 2003 KEYWORDS Balloon mitral commissurotomy; Young; Follow-up; Restenosis Introduction Mitral stenosis is rarely seen in children and adolescents except in developing countries where rheumatic fever is still endemic. 1 3 It is well known that mitral stenosis at this age is often associated with frequent episodes of pulmonary edema prompting the need for therapeutic intervention. 1 5 Until the mid-1980s, surgical closed or * Corresponding author. Habib Gamra, MD, Cardiology Department, Fattouma Bourguiba University Hospital-5000 Monastir, Tunisia. Tel.: ; Fax: address: hgamra@rns.tn (H. Gamra). Aims To evaluate the safety, efficacy and long-term actuarial results of balloon mitral commissurotomy in young patients with severe rheumatic mitral stenosis. Methods and results Event-free survival and freedom from restenosis were analyzed in 110 patients 20 years old or younger (group 1) and compared with those of 554 adults (group 2). Young patients were less frequently in atrial fibrillation (6% vs 35%, P<0.001) and had less mitral valve deformities (echo score 5.9±2.1 vs 7.5±3.0, P<0.0001). Mitral valve area index by 2D-echo was of 0.66±0.1 cm 2 /m 2 in group 1 and 0.67±0.1 cm 2 /m 2 in group 2 (P=ns) and was larger in group 1 (1.5 vs 1.3 cm 2 /m 2 ) after the procedure (P<0.0001). There were more complications in group 2 (8.4% vs 0%, P=0.01). Procedural success was obtained in 110 (100%) patients of group 1 vs 501 (92%) patients of group 2 (P<0.0001). At follow-up mitral valve area index was 1.34 cm 2 /m 2 in group 1 and 1.16 cm 2 /m 2 in group 2 (P<0.0001). At 10 years, freedom from restenosis was 61% in group 1 vs 71% in group 2 (P=0.35) and event-free survival was 74% and 69% respectively (P=0.15). Conclusion Balloon mitral commissurotomy is safe and effective in young with rheumatic mitral stenosis and provides better immediate results than in adults. However long-term outcome was similar between the 2 groups: 2/3 of patients were alive and free from clinical events at 10 years Published by Elsevier Ltd on behalf of The European Society of Cardiology. open commissurotomy was the only available treatment. However, mitral valve surgery in children and adolescents, in addition to its acute risks, has the added disadvantage that because the initial surgery is performed at an early age, reintervention may be necessary 10 to 15 years later. In adults, balloon mitral commissurotomy yielded similar results than those obtained after open surgical commissurotomy 6,7 and better results than those obtained after closed commissurotomy. 6 Therefore, balloon mitral commissurotomy appears to be an attractive alternative in that particular setting where mitral valve is pliable with minimal calcifications X/03/$ - see front matter 2003 Published by Elsevier Ltd on behalf of The European Society of Cardiology. doi: /s x(03)

2 1350 H. Gamra et al. Table 1 Baseline characteristics Group 1 (n=110) Group 2 (n=544) P Age (years) 16±2.8 37±11.9 <0.001 Female 75 (68%) 399 (73%) ns Atrial fibrillation 6 (6%) 189 (35%) <0.001 Previous commissurotomy 12 (10.8%) 98 (18%) ns Body surface area (m2) 1.44± ±0.18 < NYHA a III 76 (69%) 373 (69%) ns Echo-score 5.9± ±3.0 <0.001 Mitral regurgitation Grade 1 8 (7.2%) 65 (21.0%) ns Grade 2 1 (0.9%) 6 (1.1%) ns Left atrial size (mm) 43±9 55±11 P<0.001 a NYHA=New York Heart Association Although this procedure has been extensively used in adult and elderly patients with both short and long-term follow-up results abundantly reported, 8 18 there is no much published data on its long-term outcome in juvenile patients. Thus the purpose of this study was to evaluate the immediate and long-term (up to 10 years) results of balloon mitral commissurotomy in patients 20 years old or younger. Furthermore, we also sought to compare and contrast these results with those obtained in the adult population. Methods Study population Clinical characteristics A total of 654 patients with severe rheumatic mitral stenosis underwent balloon mitral commissurotomy in our institution between November 1987 and December Of these patients, 110 were 20 year-old or younger (Group 1) while the remainder (n=544) constituted Group 2. The baseline characteristics of both groups are shown in Table 1. Mean age was of 16 years (range: 8 20) in group 1 vs 37 years (range: 21 76) in group 2. There were more patients with atrial fibrillation in the adult population. Patients were equally symptomatic in both groups prior to the procedure and two thirds of each group were in class III or IV of New-York Heart Association functional classification. Echocardiographic evaluation All patients underwent a 2D echo-doppler examination before the procedure. Mitral valve structure was assessed using Wilkins score 19 which was less favorable in adults than in young patients as shown in Table 1. An echo score >8 was found in 16 (15%) patients of group 1 vs 201 (37%) patients of group 2 (P=0.0001). Mitral valve area was determined by 2D echo planimetry. Because of the difference in body surface area between the young and adult populations, mitral valve area index was considered for comparison. Mitral regurgitation was assessed by color Doppler using Helmcke classification 20 which is based on a scale of 1 to 4 according to the degree of jet extension into the left atrium. Prior to the procedure, special care was taken to rule out any clots in the left atrium or the left atrial appendage by transesophageal echocardiography that was systematically performed in every patient since April In addition transesophageal echocardiography provided additional information on the mitral valve structure and the severity of mitral regurgitation. Echo-Doppler examination was repeated within 24 h after the procedure to evaluate mitral valve area, to assess the severity of mitral regurgitation and to detect the presence of atrial septal defect. Mitral commissurotomy procedure After obtaining an informed consent from the patient or the parents, the procedure was performed under local anesthesia. Right and left heart catheterization was performed using respectively a 7 Fr sheath for the right femoral vein and a 6 Fr sheath for the left femoral artery. Intracardiac pressures were recorded and left ventriculography performed in all patients (except for 52 pregnant women), before and after the procedure. Transseptal puncture was performed using a Brockenbrough needle and 7 Fr Mullins sheath through the right femoral vein. Double balloon technique was used in 96 (87.3%) patients of group 1 and 455 (83.6%) patients of group 2 whereas Inoue technique was utilized in

3 Balloon mitral commissurotomy in the young (12.7%) patients of group 1 and 89 (16.4%) of group 2 (P=ns). Balloon size was selected according to the body surface area. The procedure with either technique was performed as previously described. 11,14 Follow-up evaluation After discharge, patients were requested, as part of the research protocol to return every six months during the two first years and at yearly intervals thereafter for clinical and echo-doppler evaluation. Data were additionally obtained for clinical care purposes if indicated. At a mean follow-up of 66±23 months (range: 6 to 144), clinical and echo-doppler data was available in all group 1 patients. For group 2, data was available in 534 (98%) patients at a mean follow-up of 64±16 months (range: 1 134). Mitral valve restenosis was defined as a mitral valve area index <0.9 cm 2 /m 2 by 2D echo. The threshold of 0.9 derives from the usual threshold of valve area in adults of 1.5 cm2 divided by the mean body surface area among our adult population which was of 1.7 m2. A clinical event was defined as: (1) death from any cause, (2) mitral valve replacement, (3) repeat balloon mitral commissurotomy, or (4) New- York Heart Association class III or IV. Procedural death and emergent mitral valve replacement following the procedure were included in the follow-up clinical events. To prevent rheumatic fever, patients were given benzathine penicillin G up to the age of 35 years. Statistical analysis Data are expressed as mean±standard deviation. Continuous variables were analysed using unpaired Student's t test and categorical variables using Chisquare and Fisher exact test. Comparison of variables before and after the procedure was carried out using paired t test. Twenty-six baseline clinical, echocardiographic and procedural variables were tested to determine significant univariate correlates of immediate success in the overall group. Variables with a significance level of P<0.25 were entered in a multiple stepwise logistic regression model to identify independent predictors of procedural success with a final significance level of P<0.05. Kaplan Meier analysis was used to determine survival rate, event-free survival and restenosisfree survival. Differences in survival rates between the two groups were analysed by the Log-rank test. To identify independent predictors of event-free Table 2 survival, in both groups, a Cox proportional hazard regression analysis using backward selection with a threshold of P<0.05 was performed. All analyses were performed using Stata software version 5.0 (Stata corporation, Texas, USA). Results Complications during the procedure in both groups Immediate results Group 1 Group 2 P Procedural death 0 3 (0.5%) ns Tamponade 0 4 (0.7%) ns Systemic embolism 0 9 (1.4%) ns Mitral regurgitation (5.5%) Total 0 46 (8.4%) 0.01 The procedure was completed in all group 1 patients and in 537 (98.7%) of group 2 patients. There was no death in the young population vs 3 in the adult population: 2 because of left ventricular perforation and 1 from a stroke that occurred during the procedure. Overall, the only complication encountered in the young population was a transient leg ischemia observed after the procedure and which was most likely related to femoral artery puncture. The list of complications in both groups is shown in Table 2. Hemodynamic parameters significantly improved in both groups as shown in Table 3 (all P<0.001). Mitral valve area by echo increased from 0.95±0.20 to 2.13±0.3 cm 2 in group 1 and from 1.06±0.2 to 2.15±0.4 cm 2 in group 2 (P=ns) Mitral valve area index by echo which was of 0.66 cm 2 /m 2 in group 1 and 0.67 cm 2 /m 2 in group 2 (P=ns) significantly increased to 1.5±0.3 and 1.3±0.3 cm 2 /m 2 respectively (P<0.001; Fig. 1). The same pattern was observed among patients with an echo score <8 (Fig. 2). Residual stenosis defined as mitral valve area index <0.9 cm 2 /m 2 after the procedure was found in 13 (2.3%) patients of group 2 vs none of group 1 patients (P=ns). No severe mitral regurgitation ( grade 3) was observed in the young group. In contrast, severe mitral regurgitation was observed in 30 (5.5%) patients of the adult group. Procedural success defined as a mitral valve area index 0.9 cm 2 /m 2 with no severe mitral regurgitation after the procedure, was obtained in 110

4 1352 H. Gamra et al. Table 3 Hemodynamic parameters before and immediately after the procedure Group 1 Group 2 P Pressures (mm Hg) Left atrium Pre 29±8 27± Post 13±6 15± Pulmonary artery (systolic) Pre 55±20 52±20 ns Post 37±15 37±14 ns Mean mitral gradient Pre 23±8 20± Post 5±3 6±4 ns Cardiac index (l/min/m 2 ) Pre 3.2± ± Post 3.7± ±0.8 <0.001 Mitral valve area (cm2) Pre 0.90± ± Post 2.2± ±0.4 ns Mitral valve area index (cm 2 /m 2 ) Pre 0.63± ±0.1 ns Post 1.57± ±0.1 <0.001 Fig. 1 Mitral valve area index before (Pre) and after (Post) balloon mitral commissurotomy and at follow-up (F/U) in both groups. Fig. 2 Mitral valve area index before (Pre) after (Post) the procedure and at follow-up (F/U) in patients with echo score 8 in both groups. (100%) patients of group 1 vs 501 (92%) patients of group 2 (P<0.001). Long-term results Event-free survival The clinical events that occurred in both groups during follow-up are shown in Table 4. In group 1, all patients were alive, and 14 of them (12.7%) had a clinical event. The remaining 96 patients were in functional class I (n=89) or II (n=7). In group 2, 97 patients (17.8%) had a clinical event including 10 additional deaths all from cardiac causes. The remaining 437 patients were alive in functional class I (n=379) or II (n=58) without further cardiac intervention. The probability of event-free survival (Fig. 3) was 90% at 5 years and 74% at 10 years in group 1 vs 83% and 69% respectively in group 2 (P=0.15). There was no univariate predictor of adverse clinical events in the young. In contrast, in the adult group, echo-score and cardiac rhythm were pre-procedural predictors whereas mitral valve area index, left atrial pressure and mitral regurgitation were post-procedural predictors of adverse clinical events (Table 5).

5 Balloon mitral commissurotomy in the young 1353 Table 4 Clinical events during follow-up in both groups Group 1 Group 2 P Death 0 13 (2.5%) ns Reintervention 14 (12.7%) 84 (15.4%) ns Redo balloon mitral commissurotomy 13 (11.8%) 33 (6%) 0.02 Mitral valve replacement 1 (0.9%) 51 (9.3%) Total 14 (12.7%) 97 (17.8%) ns Fig. 3 Freedom from clinical events by Kaplan Meier analysis. Number of patients evaluated in both groups at 3, 5, 7 and 10 years of follow-up are indicated. Table 5 Predictors of event-free survival according to univariate analysis in both groups Group 1 Group 2 Echo-score 0.9 <0.001 Sex Mitral valve area index (Pre) Mitral valve area index (Post) 0.4 <0.001 Previous commissurotomy Cardiac rhythm 0.3 <0.001 Left atrial pressure (Pre) Left atrial pressure (Post) Mitral regurgitation (Pre) Mitral regurgitation (Post) 0.6 <0.001 No patients in neither group developed symptoms suggesting recurrent rheumatic fever during follow-up. Freedom from restenosis Doppler echocardiographic follow-up results were available in all group 1 and in 514 group 2 patients (patients with significant residual mitral stenosis or early events were excluded). Mitral valve area index decreased from 1.5±0.3 to 1.3±0.3 cm 2 /m 2 but remained significantly higher compared with the baseline value (P<0.001) and with mitral valve area index in the adults which was of 1.16± 0.3 cm 3 /m 2 (P<0.001) as shown in Fig. 1. Restenosis was found in 14 (12.7%) young, 13 of whom had a successful repeat balloon mitral commissurotomy and one underwent mitral valve replacement because of associated grade 2 mitral regurgitation. Restenosis was observed in 83 adults (16.1%), 33 had a repeat procedure and 20 underwent mitral valve replacement. The remaining 30 patients were asymptomatic and therefore did not require reintervention. Actuarial freedom from restenosis at 5 and 10 years was 91% and 61% respectively in group 1 vs 88% and 71% in group 2 (P=0.35, Fig. 4). No predictor of restenosis was found in group 1 using the univariate analysis. However in group 2, cardiac rhythm, echo-score and previous commissurotomy were preprocedural predictors whereas left atrial pressure and mitral

6 1354 H. Gamra et al. Fig. 4 Freedom from restenosis by Kaplan Meier analysis. Number of patients evaluated in both groups at 3, 5, 7 and 10 years of follow-up are indicated. regurgitation were post procedural predictors of restenosis. Discussion Previous reports of balloon mitral commissurotomy in young populations examined small number of patients except for Sinha et al. 33 who reported a series of 193 patients. Follow-up is often limited to weeks 22,23,28 or months 27,29 32 except for Zaki et al. 34 who reported five years follow-up results.to the best of our knowledge, our study represents the largest sample size with the longest follow-up period reported. Immediate results The immediate results of balloon mitral commissurotomy in young were better than in adults with a significant larger mitral valve area index and fewer complications; however, there was no statistically significant inter-group differences in most of the hemodynamic variables. Procedure complications were not encountered in the young. In contrast, 46 (8.4%) adult patients experienced complications (P=0.01). This is most likely related to the more favourable anatomy in the young as demonstrated by a lower echocardiographic score. In fact, the severely diseased mitral valves usually seen in adults are associated with enlarged left and right atria, thickened and sometimes calcified inter-atrial septum that makes both the atrial puncture and the balloon passage more difficult. In fact, in our population young patients had significantly smaller left atrial dimension than adults (Table 1). Furthermore, balloon placement is considerably easier across a pliable than a calcified valve. All of these factors make the procedure easier, smoother and shorter in young patients. Our results are comparable to the ones reported by others. 26,28,33,34 For example, in Bahl study, 28 the better results obtained in the children population were attributed to the more diseased subvalvular apparatus in the adult population. In order to examine whether the outcome differences in our study was solely attributable to the difference in echo-score, we compared mitral valve area index between patients with an echo-score 8 in both groups (Fig. 2). Such analysis revealed similar results to those obtained in the whole population, which supports the hypothesis that there may be a role for factors besides echo-score such as left atrial size. In addition, the typically inferior echogenicity found in the adult patients makes it more difficult to accurately assess the echoscore which thereby would be underestimated. Long-term results Event-free survival Although the difference in clinical events between the two groups was not statistically significant, there were fewer events in the young population. There was no death and the only clinical events were related to reintervention procedures for restenosis and/or significant mitral regurgitation. Kaplan Meier analysis showed that 90% and 74% of the young population vs 83% and 69% of the adult

7 Balloon mitral commissurotomy in the young 1355 population were alive and free from clinical events at 5 and 10 years of follow-up respectively. The lack of inter-group differences in survival and adverse clinical events (Figs. 3 and 4) was probably because our adult population was relatively young (mean age: 37±11.9 years). In contrast, the mean age in other published studies, particularly those from Western countries, is typically higher; for example 54±15 years in the NHLBI mitral balloon valvuloplasty registry 9 and 45±15 years in the study of Iung and colleagues. 15 Not surprisingly eventfree survival was lower in such populations with for instance a 51% freedom from clinical events at 36 months for Cohen, 8 60% at 4 years for Dean 9 and 56% at 10 years for Iung. 15 In contrast, our results are comparable to those of Zaki et al. 32 who found an event-free survival of 91% at 5 years among 46 children and adolescents. Restenosis Restenosis rate was lower although not statistically different in young vs adult patients. Restenosis, which was defined by echocardiographic criteria, did warrant a reintervention in 13 (11.8%) young vs 53 (9.7%) adults. The remaining patients were free of symptoms and therefore did not have any reintervention. Although direct comparison between our results and those of surgical commissurotomy can not be made because of the lack of published data, we believe that our data offer strong arguments for consideration of balloon mitral commissurotomy as the technique of choice for the treatment of juvenile rheumatic mitral stenosis. Further encouragement derives from the fact that all of the young patients that developed restenosis were able to undergo a successful repeat procedure. The slightly higher rate of reintervention in the young group may be explained by the fact that restenosis is more often symptomatic for patients engaged in physical activity. The lack of significant predictors of restenosis in young is most likely related to the small sample size as only 14 patients developed that event. Although there was no link between restenosis and recurrent rheumatic fever in our population, patients should be given Benzathin Penicillin G at least up to the age of 35 to prevent such an event. Reintervention Balloon mitral commissurotomy was repeated in all young patients who had restenosis. In fact, all of them had a pliable mitral valve apparatus suitable for a repeat procedure. The repeat procedure was successful in all cases. In contrast, only 33 among 82 adult patients (40.2%) had repeat balloon mitral commissurotomy. The remaining patients had calcified valves that required replacement. Of interest, none of our patients that was sent for surgery because of restenosis had a surgical open commissurotomy, suggesting patients who are not good candidates for repeat balloon mitral commissurotomy are unlikely to be good candidates for surgical commissurotomy. In summary, balloon mitral commissurotomy in young patients is effective, safe and provides better immediate results than in adults particularly with regard to acute complications. Although indexed mitral valve area was larger than in adults, freedom from restenosis and from clinical events at 10 years was not statistically significant between the two groups: 2/3 were alive and free from clinical events at 10 years.these encouraging results support the validity of this technique as a procedure of choice for the treatment of mitral stenosis especially in children and adolescents. Acknowledgements We thank Peter Whittaker, PhD, for reviewing and Jamila Rassas for preparing this manuscript. References 1. 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