The effect of renal transplantation on left ventricular mechanical dyssynchrony and remodeling: A prospective study based on gated SPECT myocardial perfusion imaging

Background: End stage renal disease (ESRD) is associated with concentric left ventricular (LV) remodeling leading to hypertrophy, dilatation and poor LV contractile function. Moreover, the LV mechanical dyssynchrony (LVMD) associated with ESRD is a poor prognostic predictor. Although, renal transplant is known to improve the contractile functions of LV, the long-term effect on reversibility of LVMD is still debatable and studies have shown conflicting results.

Methods: This ongoing prospective study (Institutes Ethics Committee approved) of eighteen consecutive patients (M/F=16:2) includes analysis of pre- and post-renal transplant LVMD parameters (Phase Band Width: PBW, Phase Standard Deviation: PSD and entropy), contractile parameters [End Diastolic & End Systolic volumes (EDV & ESV), LV ejection fraction (LVEF)] and remodeling indices [LV mass (grams), Sphericity Index: SI (ratio of LV long-axis diameter to LV vertical diameter on the end-diastolic vertical long-axis frame), Eccentricity Index, EI ranging from 0 (sphere) to 1 (line)] on gated SPECT myocardial perfusion imaging (MPI). None of these patients had perfusion defects in MPI. The median interval between the transplant and the second MPI was 26 months (range: 12-38). All the patients were non-dependent on dialysis and having urea (mean 35 mg/dl; range: 12-67) and creatinine (mean 1.1 mg/dl; range: 0.8-1.2) within normal range at the time of second MPI.

Results: There was significant reduction in EDV (129.1±39.6 ml in pre-transplant vs 66.4±21.0 ml in post-transplant, with mean difference of 62.7 ml; p=0.0001) and ESV (69.8±31.6 ml in pre-transplant vs 20.5±15.6 ml in post-transplant, with mean difference of 49.5 ml; p=0.0001) along with significant improvement in LVEF (49.2±12.5% vs 71.7±13.6%, mean improvement of 22.4±6.1% with p=0.0001) suggesting overall improvement in the contractile function in the post-transplantation. Significant improvement was noted in LVMD parameters in post-transplant patients as suggested by a decrease in the mean PBW and PSD i.e. 33.6±4.2^º (66.3±36.4^º vs 32.7±13.8^º; p=0.001) and 4.8±1.6^º (11.8±4.2^º vs 6.9±2.9^º; p=0.001) respectively from the pre-transplant values. Similarly entropy also decreased from 54.0±10.1 to 47.1±10.5 (p=0.02) from pre- to post-transplant studies. Additionally, the LV mass (gm) reduced significantly from 184.6±34.1 vs 123.8±21.8 in post-transplant study with mean reduction of 60.8±7.2 gm suggesting reversal of LV hypertrophy (p=0.001). We also noted improvement in the LV dilatation/remodeling parameters suggested by increase in the sphericity index (1.5±0.2 vs 1.8±0.2; p=0.001) and eccentricity index (0.79±0.1 vs 0.83±0.1, p=0.001).

Conclusions: The results of the ongoing study objectively show that renal transplantation improve the LVMD and LV remodeling along with contractile functions on basis of gated SPECT MPI parameters.