Eight RCTs (n=546 patients) were included in the review. Study sample size ranged from 20 to 190 patients. Loss to follow-up, where reported, varied from less than 2% to 20%. Quality scores were not estimated; most trials did not provide sufficient information on their methodology to enable quality assessment.
Primary outcomes: Compared with unstented valves, there was no statistically significant difference in the left ventricular mass with stented valves prior to six months (SMD -0.1, 95% CI –0.49 to 0.29; four RCTs, I2=50%) and after six months (SMD -0.11, 95% CI -0.46 to 0.24; four RCTs, I2=51%). Compared with unstented valves, there was no statistically significant difference in mean gradients with stented valves prior to six months (WMD -1.86, 95% CI -5.22 to 1.5; three RCTs, I2=76%) and at 12 months (WMD -0.24, 95% CI -1.6 to 1.12; two RCTs, I2=4%).
Sensitivity analyses did not reveal any significant differences for left ventricular mass. Sensitivity analysis of transvalvar gradients showed a difference postoperatively when four RCTs with no preoperative data were added, but not for early and late outcomes.
Secondary outcomes: Compared with unstented valves, there was a statistically significant difference in peak gradients with stented valves for early outcomes (WMD -6.63, 95% CI -9.6 to -3.66; four RCTs, I2=49%) in favour of unstented valves. There was no significant difference for preoperative outcomes or late outcomes, unless previously excluded studies were introduced into the analysis.
Results for postoperative mean gradients and orifice areas were reported in the review.