Since its introduction in 1984 by Inoue et al.,1 percutaneous mitral balloon valvuloplasty (PMBV) has been accepted as an effective procedure for the treatment of severe mitral stenosis with immediate and short-term results comparable to those of surgical commissurotomy.2–7 Over the past years, several large series of patients undergoing PMV have demonstrated low rates of significant complications, such as perforation, tamponade, severe mitral regurgitation (MR), cerebrovascular accident (CVA) and death.8–10 There is no unique technique for PMBV, and most require transseptal left heart catheterization.1,11 In 1990, Stefanadis et al. introduced a purely transarterial method for balloon valvuloplasty12,13 that was developed with the aim to avoid complications associated with the transseptal approach.14 Previous studies indicate that the application of retrograde nontransseptal balloon mitral valvuloplasty (RNT) is a safe and effective technique for the treatment of symptomatic mitral stenosis.15,16 There are no trials directly comparing the Inoue (IN) and RNT techniques. This analysis compares the immediate and long-term results of the two techniques in patients undergoing PMBV in a single center. METHODS Patients. All patients undergoing PMBV from October 1993 to December 1999 at the 1st Cardiologic Clinic of Onassis Cardiac Surgery Center were identified. The study included 72 patients (7 men) who underwent PMBV with either the Inoue balloon method (n = 35; group IN) or the retrograde non-transseptal balloon method (n = 37; group RNT). All patients included in the study had moderate to severe MS with a mitral valve area (MVA) 10, severe MR > grade 2, left atrial thrombi or significant aortic valvular disease were excluded.17 Data collection. After discharge, patients underwent clinical review within 3 months and subsequently at maximum intervals of 1 year. Baseline data were obtained by review of medical records. Follow-up information was collected from medical records and/or telephone interview. This information included survivorship, mitral valve replacement (MVR), MACE (MVR, repeat PMBV) and clinical evaluation according to the NYHA classification of congestive heart failure symptoms. Inoue and RNTBV techniques. The two techniques used have been previously published.18,19 Two experienced physicians, each consistent with one method, performed all procedures. Complete right and left heart catheterizations with determination of intracardiac and intravascular pressures, arterial and venous blood oxygen saturations by oximetry, and cardiac output (CO) were performed immediately before and after PMBV. CO was calculated according to the Fick principle with measured body oxygen consumption and in some patients with thermodilution. Blood oxygen saturations were also determined after PMBV to detect interatrial left-to-right shunts. The MVA was calculated immediately before and after PBV according to the Gorlin formula using the CO determined with the Fick principle.20 During the procedure, all conventional hemodynamic parameters were monitored. Before and immediately after PMV, contrast left ventriculography was performed to detect possible new or changed severity of MR graded according to Seller’s criteria. Echocardiographic evaluation. Two-dimensional and Doppler echocardiography was performed in all patients the day before and after the PMV, using a Hewlett-Packard Sonos 1000 or 2500 imaging system equipped with a 2.5 MHz transducer. Transesophageal echocardiography was performed in all patients 1–2 days before the procedure in order to exclude left atrial thrombus. All echocardiograms were performed and reviewed by two experienced echocardiographers and were videotaped and stored in super-VHS cassettes. All estimates of mitral valve area were determined by Doppler echocardiography and, when possible, by direct planimetry. MR was detected and semiquantitatively graded with color flow imaging. The morphological features of the mitral valve, which include leaflet mobility, thickness, calcification and possible subvalvular disease, were graded using a 4-grade system.21 The total echo score, with a maximum of 16, was the sum of the individual components. On the day after the procedure, a new echocardiogram was performed and the MVA was measured by the same method. The PMBV was considered successful if there was > 50% increase in MVA and/or final MVA > 1.5 cm2 with an MR 50% of the initial gain in valve area. Statistical analysis. Numerical values were expressed as means ± standard deviation (SD) and categorical variables as percentages. Student’s t-test and Chi-square analysis were carried out for comparison of continuous and categorical variables, respectively. Kaplan-Meier estimates were used to determine event-free survival rates for both groups. All analyses were performed with the SPSS version 10.0 statistical package (standard version). P-values Baseline characteristics. Baseline characteristics of the patient groups are shown in Table 1. There were no significant differences between the two groups in terms of NYHA functional class, cardiac rhythm, total echo score, body surface area (BSA), MVA and MVA gradient. IN patients were slightly older compared to RNT patients. It must be noted that more than 70% of patients of both groups had atrial fibrillation and more than 80% were in NYHA class III or IV at baseline. Immediate outcome. Procedural and in-hospital outcomes are shown in Table 2. PMBV was completed successfully in 32 of 35 IN patients and 33 of 37 RNT patients; there was no procedural death, tamponade, perforation or embolism. One patient of the IN and two patients of the RNT group had to undergo emergency operation due to significant MR (grade > 3). There were nonsignificant differences in the increase in the echocardiographically calculated MVA between the two groups (p = NS). In addition, a parallel reduction in transmitral diastolic gradient was achieved. There was a higher percentage of mild MR in the RNT group (p = 0.03). Other in-hospital complications besides minor vascular complications (hematomas) in both groups and a pseudoaneurysm in the RNT group at the site of the instrumentation of the sheaths were not reported. The mean fluoroscopic time was shorter in the IN group (31 ± 16 minutes vs. 39 ± 11 minutes in the RNT group) (p = 0.02). Follow-up outcome. There were no reported deaths in either group. At a mean follow-up of 42 ± 12 months, twenty-nine patients (83%) of the IN group and 29 patients (79%) of the RNT group continued to experience favorable clinical status (NYHA class I or II). These data are shown in more detail in the Kaplan-Meier plots in Figure 1. Late echocardiographic reassessment was available in 57 patients (80%). Echocardiographic restenosis was detected in 3 patients of the IN group and 5 patients of the RNT group. In the IN group, mitral valve replacement was performed in 2 cases, repeat PMBV in one case and deterioration of NYHA class (> III and above) in one case (episode of pulmonary edema). In the RNT group, MVR was performed in 4 cases, repeat PMBV in one case and deterioration of functional class in 3 patients (all with mitral valve restenosis). One patient of the IN group experienced a non-fatal (embolic) CVA and one patient from the RNT group had a peripheral (lower extremity) embolism (Table 3). DISCUSSION Our findings suggest that the IN and RNT techniques are comparable regarding the achieved MVA, with slightly more frequent MR with the RNT technique. The IN technique requires significantly less fluoroscopy time. MACE and event-free survival rates at follow-up were similar in the two groups Inoue versus retrograde non-transseptal technique. With the Inoue technique, a transseptal puncture is used during cardiac catheterization to gain access to the mitral valve area from the left atrium.1 A single deflated balloon is advanced from the venous circulation to the right atrium, across the interatrial septum to the left atrium and across the stenotic valve. Inflation and rapid deflation of the balloon opens the stenotic valve via separation of the fused commisures.3 Fracture of calcific deposits in the leaflet tissue may also contribute to improved leaflet mobility and separation, as in surgical commisurotomy.4 Logically, the same mechanism applies to the RNT PBMV, which is a purely transarterial method.11 An externally steerable catheter enters the left atrium retrogradely via the left ventricle. Moreover, the technique has the advantage that it does not involve puncture of the interatrial septum, although it is implicated with femoral arterial damage. In our series, there were no reported major arterial complications apart from small hematomas at the site of femoral artery puncture. Although there is less worldwide experience with the RNT technique, the results appear to be equivalent to the transseptal approach. In our study, the two techniques share similar results concerning the immediate and follow-up outcomes. The Inoue technique required shorter fluoroscopic time. It must be noted that a number of patients in the RNT group (51%) were undergoing an investigative protocol affecting the procedural time but not the fluoroscopy time. An intriguing finding may be that there was a higher percentage of mild MR following the RNT technique. A logical explanation for this difference could be the larger number of attempted dilatations, the differences in balloon sizing or the greater slippage of balloons used in the RNT technique. The increase in mitral valve area was more modest for both techniques than that achieved in other studies.9,15,22,23 However, major complications were also fewer, and it is possible that a greater increase in valve area is achieved at the expense of more frequent complications such as severe mitral regurgitation.24,25 It is of note that in our series, the incidence of severe MR was only 5% for the IN group and 8% for the RNT group. In addition, patients in our study had a higher frequency of unfavorable clinical conditions (such as atrial fibrillation and NYHA class III or IV status) than previous reports,22,23 and thus comprised a high-risk population. Despite these adverse characteristics, the procedure was completed in 91% of IN patients and 89% of RNT patients. Procedural mortality was zero, with initial symptomatic improvement in 92% of the IN group and 86% of the RNT group. Study limitations. There are a number of limitations to the current study. First, it must be noted that this is an observational study. Patients were not studied under protocol condition and they represent a “real life” population. Second, even though it was a single-center study, different operators performed the two techniques. However, the operators (both with established experience) were consistent by using one of the techniques. Third, during the procedure there was not a universal approach concerning the size of the balloon used and the number of the dilations attempted; therefore, different balloon sizing and dilation methods were used in each technique. Moreover, a significant percentage of cases either were lost to follow-up (7%) or lacked echocardiographic reassessment (20%). In addition, this study included a relatively small number of patients. While this may be considered to have skewed the data favorably, our intention was to present a complete data set from a typical Western population in order to establish the overall acute and long-term results that might be expected in such a patient group with the use of each of the techniques described. CONCLUSIONS The IN technique was compared to the RNT in a single center. In this study, the fluoroscopic time was shorter in the IN group. There was also a higher percentage of mild valve regurgitation following the RNT technique. Other than that, the two techniques share comparable clinical and echocardiographic results in the immediate and long-term outcome.
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