Studies have shown that resynchronization of the ventricles leads to reduction of functional mitral regurgitation and to a better clinical profile. To throw more light onto this, Dr. M Petrovic and coworkers performed the present trial that assessed the positive effects of resynchronization therapy on reduction of mitral insufficiency in their responders' group, as it was shown to be associated with dyssynchrony improvement and left ventricular reverse remodeling after resynchronization at mid-term follow-up.
Study population for this trial included 57 patients (80% men) with idiopathic dilated cardiomyopathy and standard inclusion criteria (New York Heart Association class-NYHA class III or IV heart failure, left ventricular ejection fraction ≤ 35%, QRS ≥120 ms, and optimal medical therapy).
As a part of this study, researchers evaluated the clinical status and echocardiographic parameters (conventional and tissue Doppler imaging) before and at 12 months after the CRT. All-cause mortality and change in NYHA class comprised the clinical outcome.
Findings from this study showed an echocardiographic left ventricular reverse remodeling (end-systolic volume decreased more than 15 %) was reported by 54% of the 57 patients (average age was 59. 9 years) and were responders to CRT.
At 12 months follow-up in responders' group, a statistically significant decrease in PISA radius and a significant decrease in mitral regurgitation velocity-time integral, PISA and the peak velocity of mitral regurgitation were observed (table 1).
Table 1: Responders group vs. Non responders group
|
|
PISA radius |
Mitral regurgitation velocity-time integral |
PISA |
peak velocity of mitral regurgitation |
| Non responders group |
0.64 ±0.15cm |
1.3 ±0.4cm |
2.4±0.9 cm2 |
4.4±0.7m/s |
| Responders group |
0.4±0.25cm |
1.0±0.5cm |
1.8±1.6cm2 |
3.9±0.9m/s |
| P values |
0.011 |
<0.05 |
|
|
Also, significantly decreased degree of mitral regurgitation as assessed by color Doppler was reported (p<0.01). Additionally, there was a significant association of an improvement of mitral regurgitation with the shortening of interventricular mechanical delay and septal-to-lateral wall delay (table), as was reverse remodeling of left atrium and decrease in left atrium diameters, p<0.05.
Table 2: Improvement of mitral regurgitation and reverse remodeling of left atrium and decrease in left atrium diameters
| |
Interventricular mechanical delay |
Septal-to-lateral wall delay |
| Before 12 months follow up |
60.7±25ms |
105±52 ms |
| At 12 months follow up |
32.5±28ms |
36±47 ms |
| P values |
<0.001 |
<0.001 |
Furthermore, all of responders had a statistically changed NYHA class with an improved clinical status. Higher survival rate was reported in responders group.
Based on all the above findings, this study concluded that the reduction in mitral regurgitation after the resynchronization therapy was associated with left ventricular reverse remodeling and dyssynchrony improvement at mid-term follow up. This reduction contributed to a better clinical status of responders. | 
