Late Clinical Outcomes of Percutaneous Mitral Commissurotomy in Patients With Mitral Stenosis
Condition: Mitral Valve Stenosis
MeSH terms: Mitral Valve Stenosis; Constriction, Pathologic
Study type: Observational [Patient Registry]

Summary: 
      In this retrospective cohort study, out of 220 patients who had undergone successful PTMC
      between 2006 and 2018, the clinical course of 186 patients could be successfully followed.
      Peri-procedural clinical and echocardiographic data were collected for these patients.
      Cardiac-related death, undergoing a second PTMC or mitral valve replacement (MVR) were
      considered adverse cardiac events in follow-up for the purpose of this study. Patients with
      no history of these events were contacted and asked to undergo echocardiographic imaging, in
      order to assess the prevalence of mitral valve restenosis, defined as mitral valve area (MVA)
      < 1.5 cm2 and loss of ≥50% of initial area gain
    

Detailed description: 
      This research was designed as single-technique (Inoue balloon), multicenter retrospective-
      prospective cohort study. The target group of this study consisted of 220 patients with
      symptomatic MS who had undergone PTMC at in 4 hospitals (Baqiyatallah, Namazi, Shahid-Faghihi
      and Kowsar) under the supervision of Baqiyatallah University of Medical Sciences and Shiraz
      University of Medical Sciences between April 2006 and January 2018. The demographic data of
      the patients were obtained from the medical records departments at each center.

      The inclusion criteria for the participants were: 1) age more than 20 years at the time of
      PTMC; 2) immediate post-PTMC mitral valve area (IMVA) ≥1.5 cm2, or for lower values, at least
      50% increase in pre-PTMC mitral valve area (MVA); 3) an initial cardiovascular event-free
      period of at least 6 months after the procedure.

      The exclusion criteria consisted of: 1) more than 2+ mitral regurgitation (MR) immediately
      after the procedure; 2) immediate cardiovascular event during the hospital stay after the
      procedure; 3) more than mild aortic stenosis or sufficiency before PTMC; 4) history of
      previous PTMC or surgical mitral procedures.

      The study design and steps were approved by the ethics committees at both Baqiyatallah and
      Shiraz University of Medical Sciences.

      PTMC Technique All PTMC procedures were done with an Inoue balloon catheter by skilled
      interventional cardiologists via anterograde trans-septal approach in all patients. Right and
      left cardiac catheterization was performed before and during the procedure to assess
      hemodynamic changes. Optimal balloon size (in millimeters) was estimated with the height
      (cm)/10 + 10 formula. The balloon was inflated in a step-wise fashion from lower to higher
      volumes. After each inflation, changes in trans-mitral mean pressure gradient (TMPG) and the
      degree of mitral regurgitation (MR) were monitored. Based on interventionist's judgement and
      in order to achieve optimal results, balloon inflation could be continued up to 1-2 mm more
      than the estimated size. In the last stage, left ventriculography was conducted to assess the
      degree of final MR.

      Echocardiography All the patient included underwent transthoracic Doppler echocardiography
      (TTE) in the week before PTMC by expert cardiologists with an advanced echocardiography
      fellowship. All general echocardiographic findings and significant mitral valve-related
      characteristics were reported. MVA was measured by planimetry in the short axis view, and
      also by pressure half-time quantification when atrial fibrillation (AF) or MR were not
      serious enough to interfere with its interpretation. The degree of MR was reported on a
      semi-quantitative scale of 0 to 4 based on Doppler color flow mapping. Mitral valve
      morphology was also evaluated with the standard Wilkins echocardiographic scoring system in
      the spectrum of 4 to 16. Pulmonary arterial pressure was estimated by measuring systolic
      pulmonary arterial pressure (sPAP) in mmHg based on the trans-tricuspid regurgitation jet.
      Other significant variables in this study were left atrial diameter in centimeters, and mean
      trans-mitral pressure gradient (TMPG) in mmHg.

      Each patient also had one session of transesophageal echocardiography during the day before
      the procedure in order to rule out thrombi in the left atrium or the left atrial appendage.
      Another session of TTE was performed during the first day after the procedure to confirm the
      immediate success of PTMC, with the main focus on mitral valve-related parameters, and also
      to rule out acute complications such as severe MR or cardiac tamponade.

      Follow-up The clinical condition of the patients was recorded as their New York Heart
      Association (NYHA) functional class before the procedure. Their clinical status was also
      followed in their inpatient and outpatient records. For the purpose of this study, the
      patients or their first-degree relatives were contacted by telephone in order to record the
      occurrence and exact timing of any adverse cardiac events, and also to reassess their current
      NYHA functional class status. Clinical events considered significant for the purpose of this
      study included: 1) cardiac-related death, 2) another session of PTMC, or 3) surgical
      procedure of mitral valve replacement (MVR). Patients who had been event-free until that time
      were asked to undergo another TTE evaluation after providing their informed consent, in order
      to compare the echocardiographic variables noted above with their previous records.

      Statistical Analysis Continuous variables are reported as the mean ± SD. Categorical and
      nominal variables are shown as the number and percentage, and were pooled in some cases in
      order to facilitate the interpretation of the results. Initially, univariate Cox proportional
      hazards regression analysis was used to assess the relationship between variables and adverse
      cardiac events at follow-up. In the next stage, Cox multivariable regression was also
      performed to single out the independent variables. To evaluate the variables for the
      occurrence of restenosis during follow-up, uni- and multivariate logistic regression analysis
      was used. Receiver operating characteristic (ROC) curves were generated to determine the best
      cut-off point for IMVA in interpreting the results. For all analyses a p-value of 0.05 or
      less was considered statistically significant. All data analyses were done with IBM SPSS
      Statistics version 23 software.
    

Intervention name(s): PTMC
Intervention type(s): Procedure
Intervention description(s): percutaneous mitral ballooning with Inoue balloon
Other intervention name(s): mitral ballooning
Observational model: Cohort
Time perspective: Other
Sampling method: Non-Probability Sample
Study population: 
        : In this retrospective cohort study, out of 220 patients who had undergone successful PTMC
        between 2006 and 2018, the clinical course of 186 patients could be successfully followed.
        Peri-procedural clinical and echocardiographic data were collected for these patients.
        Cardiac-related death, undergoing a second PTMC or mitral valve replacement (MVR) were
        considered adverse cardiac events in follow-up for the purpose of this study. Patients with
        no history of these events were contacted and asked to undergo echocardiographic imaging,
        in order to assess the prevalence of mitral valve restenosis, defined as mitral valve area
        (MVA) < 1.5 cm2 and loss of ≥50% of initial area gain
      
Keywords: percutaneous mitral commissurotomy; follow up