Cardiopulmonary Bypass Time
Four studies including 2,330 patients reported on cardiopulmonary bypass times,5,7–9 though one reported only median times for each group and could not be included in pooled analysis.7 In the remaining three studies, TVS at the time of LVAD prolonged cardiopulmonary bypass time by an average of 31 minutes per patient (Figure 1). Three7–9 out of four studies reported significantly longer bypass times with TVS.
Need for RVAD
All six studies including 3,249 patients reported on the postoperative need for RVAD for RV failure,. In pooled analyses, there was no difference in the need for RVAD in patients treated with LVAD + TVS versus LVAD alone (RR 1.42, 95% CI 0.54–3.76, I2 = 71%, Figure 2). The study by John et al.,10 which analyzed data from the HeartMate II trials, was the sole study to find a significantly higher risk of RVAD insertion in patients treated with LVAD + TVS versus LVAD alone (9.7% vs. 1.9%, p < 0.001). However, this study did not account for differences in baseline risk or degree of TR. In a subgroup analysis including the three studies6–8 that exclusively compared patients with at least moderate TR who underwent LVAD + TVS versus LVAD alone, there was still no difference in postoperative need for RVAD (RR 0.79, 95% CI 0.49–1.28, I2 = 5%, p = 0.34). Results were also similar when limiting the analysis to the three studies that solely included patients with continuous flow devices.8–10
Duration of Inotropic Support
There were three studies representing 249 patients that reported on the postoperative duration of inotropic support.5,6,9 One study reported a significantly shorter duration of inotropic support in patients treated with LVAD + TVS,6 where the median duration after LVAD + TVS was 8 days compared with 10 days after LVAD alone (p = 0.04). The remaining two studies found no difference in inotrope duration in patients treated with LVAD + TVS versus LVAD alone (mean 10.5 vs. 7.8 days, respectively,5 and 8.6 vs. 8 days.9
Acute Renal Failure
Four studies reported on the risk of postoperative acute renal failure in patients treated with LVAD + TVS versus LVAD alone, one of which reported a significantly higher risk in those with concomitant TVS. In pooled analyses including 2,020 patients, there was no difference in the risk of postoperative acute renal failure in patients treated with LVAD + TVS versus LVAD alone (RR 1.07, 95% CI 0.55–2.10, Figure 3). Between-study heterogeneity was moderate (I2 = 67%). The results from Saeed and Robertson showed more acute renal failure in those treated with TVS + LVAD compared with LVAD alone (pooled RR 1.56, 95% CI 1.16–2.11), which differed from the other two studies that demonstrated a trend toward lower risk of acute renal failure in patients treated with TVS (pooled RR 0.61, 95% CI 0.34–1.09). In reviewing the data from Saeed et al., patients with TVS had a rise in creatinine postoperatively (from an average of 1.6 mg/dl preoperatively to 2.3 mg/dl on postoperative day 14) compared with a drop in creatinine in those treated with LVAD alone, but both groups had creatinine levels that were comparable to their preoperative values by postoperative day 30. It is notable that this group reported substantial prolongation in cardiopulmonary bypass times with addition of TVS (median 70 minutes longer than patients treated with LVAD alone). The study from the STS database reported increased risk of new onset renal failure and need for dialysis in patients treated with LVAD + TVS versus LVAD alone, which persisted after accounting for propensity to perform a tricuspid valve procedure (TVP).
Hospital Length of Stay
Four studies including 2,401 patients reported on differences in hospital length of stay in patients treated with LVAD + TVS versus LVAD alone.5,6,8,9 The study pooling data from the STS database reported an adjusted 29% increased risk for prolonged hospital length of stay in patients treated with TVS compared with LVAD alone (RR 1.29, 95% CI 1.16–1.43, p < 0.001).8 One study6 reported a significantly shorter length of stay in patients treated with LVAD + TVS compared with LVAD alone (median 19 vs. 26 days, p = 0.02). Both of these studies, reporting disparate results, restricted their analyses to patients with at least moderate TR. The remaining two studies reported no differences in hospital length of stay in patients treated with LVAD + TVS versus LVAD alone (mean 32 vs. 30 days, respectively5 and 23 vs. 20 days.9
In total, all six studies representing 3,217 patients reported on early mortality, although none reported any difference in patients treated with LVAD + TVS versus LVAD alone. There was no difference in early mortality in patients treated with TVS + LVAD versus LVAD alone (Figure 4). There was low heterogeneity between studies. A subgroup analysis including the three studies that exclusively compared patients with at least moderate TR who underwent LVAD + TVS versus LVAD alone,6–8 there was still no difference in early mortality (RR 0.93, 95% CI 0.67–1.29, p = 0.67). Results were similar when limiting the analysis to the three studies that solely included patients with continuous flow devices.8–10
There were very limited data provided in any of the studies on long-term outcomes. The exception was the report from the HeartMate II trials,10 which reported no difference in 1-year (77% vs. 75%) and 2-year (63% vs. 64%) survival in patients treated with LVAD + TVS versus LVAD alone. Beyond that, three articles6,7,9 provided Kaplan–Meier curves for mortality, though there were very few patients being followed beyond 1 year in any study.
On the basis of our review of the literature and synthesis of available data, although the addition of TVS prolongs cardiopulmonary bypass times, we did not find sufficient evidence to suggest that performance of TVS at the time of LVAD implantation has an effect on early postoperative outcomes. However, most existing studies are inadequately powered and fail to adequately adjust for potential confounders. The two largest studies, analyzing data from the HeartMate II trials10 and STS database,8 found no difference in early mortality in patients treated with TVS at the time of LVAD, though one10 found a higher risk of RVAD and the other8 a higher risk of postoperative renal failure and prolonged length of stay.
TR is extremely common in patients with advanced HF, most often occurring as a result of progressive tricuspid annular enlargement and tricuspid valve leaflet tethering because of RV enlargement. The development of TR often leads to a difficult cycle of progressive RV enlargement, and in turn, worsening regurgitation. In patients undergoing valve surgery for mitral regurgitation, it is known that TR can progress after surgery11 and is associated with worse postoperative outcomes. This recognition has led to the most current guidelines from the European Society of Cardiology recommending that patients who have severe TR undergo surgical intervention at the time of left-sided valve surgery (class I), and such surgery should be considered in patients undergoing left sided heart valve surgery with at least mild TR and a dilated tricuspid annulus (class IIa).12 However, similar guidelines do not exist in patients undergoing LVAD, though the prevalence of at least moderate TR has been estimated to be nearly 50% in recent studies.1,9 Accordingly, whether TR is treated with tricuspid valve repair or replacement at the time of LVAD has largely been based on the preference of the individual surgeon. The tricuspid valve has often been viewed as a “pop-off” valve, and there is concern that fixing the TR may result in progressive RV dysfunction and failure in the early postoperative period. Furthermore, there has been some evidence that effective offloading of the left ventricle with the LVAD can result in improvement in the degree of TR,13,14 though this has been inconsistent across studies with some showing no improvement without surgical repair.15 As severe preoperative TR has been identified as a predictor of adverse postoperative outcomes,16 other centers have taken the approach of surgically repairing the tricuspid valve in patients with significant TR at the time of LVAD implantation in the hopes of improving postoperative outcomes and potentially eliminating the need for future tricuspid procedures.
In this review, we found that patients treated with TVS at the time of LVAD consistently had longer cardiopulmonary bypass times across studies compared with patients who underwent LVAD alone, which is expected. However, we found no differences in postoperative outcomes including use of RVAD, renal dysfunction, and early mortality in patients treated with LVAD+ TVS versus LVAD alone. Only three studies compared the results from patients with at least moderate TR,6–8 but there were still no differences in pooled analyses of outcomes when restricted to these studies. In the remaining studies, patients treated with TVS had more TR and worse baseline RV function, and thus were at greater risk of adverse postoperative outcomes than those who underwent LVAD alone. However, differences in baseline risk were not adjusted for in their analyses. In many cases, the fact that postoperative outcomes were similar despite this difference in risk was interpreted as indication that TVS had a positive effect on postoperative outcomes in these patients. Although there were no randomized trials on the topic to address this question, the sole study that adjusted for propensity to have TVS found a higher risk of renal failure and prolonged hospitalization in patients treated with TVS, though no difference in the need for RVAD or early mortality.8 Analyses of the impact of TVS on postoperative outcomes from the Interagency Registry for Mechanically Assisted Circulatory Support (INTERMACS) and the Heartware trials were recently presented inter(national) meetings, though full-text results have not been published. However, neither reported differences in early mortality in their published abstracts.17,18 In addition to the pooled results reported herein, Maltais et al. reported evidence of reverse RV remodeling and improved RV function after LVAD + TVS,9 though data are lacking to inform us as to whether these early changes translate into differences in long-term outcomes. As such, further work is also needed to better evaluate and understand the long-term implications of performing TVS at the time of LVAD. The increasing use of LVAD as destination therapy underscores the importance of examining this issue, as the LVAD remains in situ for the remainder of the patient’s life and the impact of TR on long-term outcomes becomes of great importance.
There are limitations to acknowledge to aid in interpretation of these data. All included studies were observational, and patient selection for TVS may have contributed to results observed. Only three studies restricted their population to patients implanted with continuous flow LVADs, while others included older generation pulsatile flow pumps. Differences in physiology and surgical implantation requirements may contribute to variation in early postoperative outcomes. However, when we restricted our analysis of RVAD and early mortality to those studies using continuous flow devices, we found results to be similar. Some studies included patients who underwent both tricuspid valve repair and replacement. As we did not have access to the individual patient-level data from the various studies, we were unable to assess whether differences in outcomes may occur as a result of the type of TVP employed.
This is the first systematic review and meta-analysis to evaluate the impact of TVS performed at the time of LVAD implantation on cardiopulmonary bypass times and early postoperative outcomes. We found that there are limited observational data available on this topic. Although cardiopulmonary bypass times appear to be longer in those treated with TVS at the time of LVAD implantation, there is insufficient information to draw definitive conclusions on the impact of TVS on early postoperative outcomes. As such, further data are needed in order to inform surgeons as to the best practice for these patients.
The authors thank Patricia Erwin for her assistance with developing a search strategy.
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Keywords:Copyright © 2015 by the American Society for Artificial Internal Organs
heart valve; circulatory assist devices; heart failure; outcomes