Aims: There has been growing attention for the development of functional tricuspid regurgitation (TR) long after left-sided valve surgery. We attempted to determine the long-term haemodynamic effects of corrective surgery for severe functional TR in patients who had prior left-sided valve surgery using cardiac magnetic resonance imaging (CMR).
Methods and results: Thirty-one patients with severe functional TR (TR fraction of 46.0+/-16.2% by CMR) were analysed. CMR was performed within 1 month before and at a median 27.0 months after surgery. Long after TR surgery, 28 of the 31 patients had no or mild residual TR, two had mild-to-moderate TR, and one showed moderate TR. Remarkable reductions in the right ventricular (RV) end-diastolic volume index (RV-EDVI) (177.4+/-59.1 mL/m(2) vs. 118.2+/-31.2 mL/m(2), P<0.001) and end-systolic volume index (RV-ESVI) (88.5+/-30.1 mL/m(2) vs. 67.2+/-31.0 mL/m(2), P=0.002) were observed, whereas RV ejection fraction (RV-EF) showed no change (49.7+/-8.3% vs. 44.9+/-12.5%, P=0.09). Pre-operative RV-EDVI (R=-0.86, P<0.001) and RV-ESVI (R=-0.55, P=0.001) were significantly associated with their respective changes after corrective surgery. Post-surgery, a normal RV-EF was achieved in 14 patients (42.5%). Pre-operative RV-EDVI of 164 mL/m(2) effectively discriminated patients with normal RV-EF from those without post-surgery, with a sensitivity of 77% and a specificity of 72% (P=0.01). A significant rise in the left ventricular (LV) EDVI and cardiac index (CI) was found after surgery (from 92.9+/-24.4 to 123.2+/-31.6 mL/m(2) for LV-EDVI, P<0.001; from 3.8+/-1.3 to 4.2+/-0.8 L/min/m(2) for CI, P=0.03). Functional capacity as assessed by NYHA class showed a significant improvement from 2.7+/-0.6 before surgery to 2.0+/-0.6 long after surgery (P<0.001).
Conclusion: Successful TR surgery can remarkably reduce RV volumes and preserve RV systolic function. In addition, successful TR surgery led to a significant rise in LV preload and CI, which may significantly contribute to a significant amelioration in the functional capacity of the patients. It seems that RV volume measurement by CMR is helpful for determining optimal timing for TR surgery.