P5272Right versus Left Ventricular Remodelling after Surgical myectomy for HOCM

Background Surgical myectomy for (HOCM) results in complex structural and functional changes. “Remodelling” in different cardiac chambers. To date, changes in the Right versus the left Ventricle have not been studied. Methods Fourty five patients (mean age = 32±16, 68% males) who underwent extended septal myectomy for LVOTO and Fourty “normal” controls (mean age = 32±12 years, 52% males) were studied by cardiac magnetic resonance imaging (CMR). The patients were studied pre-operatively and 6–18 months post-operatively (median = 9 months). The images were analysed by both commercial and in-house software. Results After myectomy. Follow up CMR showed changes in RV mass (21±5 to 23±7) g/m2, volume (60±15 to 66±12) ml/m2 and shape using 3 different methods. RV deformation parameters showed significant changes with circumferential strain (−8±2 to −14±4), filling (38±16 to 62±19) ml/s/m2 and ejection rate (−44±17 to −75±22). Changes in RV were substantially higher than those observed in the LV (Figure. 1, Table. 1). All patients reported significant symptomatic improvement with 31 (78%) patients in NYHA class I and 9 (22%) in class II at follow up. Significant reduction in peak gradient across the LVOT by 75%. Table 1. Summary of reported parameters related to RV Shape for pre and post operation HOCM patients and Normal Healthy Volunteers LV RV Pre Post Normal P-value Pre Post Normal P-value EDV ml/m2 75±18 81±14 73±10 0.005 60±15 66±12 71±12 0.002 ESV ml/m2 20±9 24±8 26±6 0.008 16±7 19±9 26±7 0.02 SV ml/m2 56±13 57±10 51±13 0.38 44±11 48±10 49±14 0.009 EF 74±7 70±7 65±5 0.001 74±8 72±7 64±6 0.228 Mass g/m2 74±33 62±29 27±8 0.0456 21±5 23±7 18±5 0.2100 PFR ml/m2 173±48 141±48 141±40 <0.0001 38±16 62±19 55±24 <0.0001 PER ml/m2 −179±35 −172±42 −144±42 0.29 −44±17 −75±22 −57±22 <0.0001 Peak Strain −20±3 −20±3 −20±3 0.49 −8±2 −14±4 −12±3 <0.0001 Conclusion LV septal myectomy is followed by structural and functional remodelling which is more extensive in the right than the left ventricle. The clinical significance of these findings needs further study.