Dragon 1 Protocol Manuscript: Training, Accreditation, Implementation and Safety Evaluation of Portal and Hepatic Vein Embolization (PVE/HVE) to Accelerate Future Liver Remnant (FLR) Hypertrophy

Preoperative risk score for 90-day mortality after major liver resection

BACKGROUND

Major liver resection is frequently performed for primary and secondary liver tumors. However, 90-day mortality rates can exceed 10% in high-risk patients. This study aimed to develop a preoperative risk score for postoperative mortality after major liver resection.

METHODS

All major liver resections between 2014 and 2019 in 2 Dutch tertiary referral centers were identified. A validation cohort consisted of all consecutive patients who underwent a major liver resection in the nationwide Dutch Hepato Biliary Audit from 2014 to 2020. Multivariate logistic regression was used to identify prognostic factors and develop a mortality risk score.

RESULTS

Major liver resection was performed in 513 patients, of whom 238 (46.4%) had a primary liver cancer, and in 148 patients (28.8%), a hepaticojejunostomy was performed; 90-day mortality occurred in 56 patients (10.8%). Mortality was independently predicted by 5 risk factors: age ≥ 65 years, diabetes mellitus type 2, diagnosis of primary liver cancer, American Society of Anesthesiologists ≥ 3, and extended hemihepatectomy. A risk score with 1 point assigned to each risk factor showed good discrimination (area under the curve [AUC], 0.77; 95% CI, 0.71-0.83). The predicted 90-day mortality was 3.5% for low-risk (0 or 1 points; 53.8% of all patients), 11.1% for intermediate-risk (2 points; 25.3%), and 29.7% for high-risk patients (3-5 points; 20.9%). External validation in the nationwide cohort with 1617 patients showed similar concordance (AUC, 0.69; 95% CI, 0.64-0.75).

CONCLUSION

The proposed and validated risk score can aid in shared decision making.

Portal and Hepatic Vein Embolization versus Portal Venous Embolization Alone in Cirrhotic and Noncirrhotic Swine: A Pilot Study

PURPOSE

To evaluate the effectiveness of combined portal vein embolization (PVE) and hepatic vein embolization (HVE) compared with that of PVE alone in cirrhotic and noncirrhotic swine.

MATERIALS AND METHODS

Sixteen Yorkshire pigs were included in this study. In the cirrhotic group (n = 8) and noncirrhotic group (n = 8), subjects underwent embolization according to established protocols. Computed tomography (CT) scans were acquired before and at 2- and 4-week intervals following the embolization. Liver volumes were segmented in the portal venous phase. Student t test with a significance level at P < .05 was used.

RESULTS

Across all swine, the future liver remnant (FLR) was significantly larger after PVE + HVE than after PVE at 2 weeks (24.12% [95% CI, 15.36%-32.88%] vs 12.75% [95% CI, 7.43%-18.07%]; P = .021) and 4 weeks (23.23% [95% CI, 15.79%-33.47%] vs 15.08% [95% CI, 9.98%-20.87%]; P = .043) after embolization. In the cirrhotic group, the FLR increase was greater following PVE + HVE than after PVE at 2 weeks (20.85% [95% CI, 14.40%-27.30%] vs 8.66% [95% CI, 6.47%-10.86%]; P = .0089) and 4 weeks (19.27% [95% CI, 17.87%-20.67%] vs 13.33% [95% CI, 9.23%-13.33%]; P = .0003) after embolization.

CONCLUSIONS

PVE + HVE resulted in greater FLR hypertrophy than PVE alone, indicating that cirrhotic livers may benefit from the addition of HVE.

Safety and efficacy of combined portal and hepatic vein embolisation in patients with colorectal liver metastases (DRAGON1): a multicentre, single-arm clinical trial

Background

Major liver resection is often required for complete clearance of colorectal liver metastases (CRLM). Patients with insufficient future liver remnant (FLR) volume/function are at high risk of post-hepatectomy liver failure (PHLF) and require FLR hypertrophy-inducing procedures to enable safe resection. The most recent variant of these procedures is combined portal and hepatic vein embolization (PVE/HVE). The DRAGON 1 trial evaluates the safety and efficacy of PVE/HVE, while assessing recruitment potential for the DRAGON 2 randomized trial.

Methods

DRAGON 1 is a prospective, single-arm, international, multicenter trial. Patients with upfront unresectable CRLM due to a small FLR were included. The primary outcome was the ability of centers to recruit three patients and perform PVE/HVE and liver resection without 90-day mortality. Secondary outcomes included recruitment capacity, PVE/HVE technical details, FLR volume changes, complications, and resection rates. The study is registered at ClinicalTrials.gov, identifier: NCT04272931.

Findings

In total, 102 patients were included from 43 centers. Twenty-four centers (24/43 = 56%) recruited three or more patients, and 20 centers (20/43 = 47%) achieved this without 90-day mortality. Of 96 patients undergoing PVE/HVE, no post-embolization mortality occurred, though major complications were reported in two patients. Resection was completed in 86 patients (86/96 = 90%), with seven patients (7/86 = 8%) dying within 90 days. PHLF grade B/C (International Study Group of Liver Surgery criteria) occurred in 19 patients (19/86 = 22%).

Interpretation

DRAGON 1 demonstrates that PVE/HVE is safe, with no embolization-related mortality, low morbidity, and high resection rates in upfront unresectable CRLM.

Funding

The Dutch Cancer Society, National Institute for Health and Care Research UK, Maastricht UMC+, Abbott Laboratories and Guerbet.

Combined Portal and Hepatic Vein Embolization Produces Greater Hypertrophy than Portal Vein Embolization Alone with Similar Post-Hepatectomy Outcomes and is not Impacted by Hepatic Artery Infusion Chemotherapy

BACKGROUND

Combined portal and hepatic vein embolization (cPVE-HVE) induces hypertrophy of future liver remnant before hepatectomy. We compared liver hypertrophy and post-hepatectomy outcomes between cPVE-HVE and portal vein embolization (PVE) alone.

PATIENTS AND METHODS

Consecutive patient outcomes after cPVE-HVE and PVE were compared across all pathologies for degree of hypertrophy (DH), kinetic growth rate (KGR), impact of hepatic artery infusion chemotherapy (HAIC), and post-hepatectomy complications at a single center.

RESULTS

The study cohort included 305 patients, 250 underwent PVE and 55 underwent cPVE-HVE. Pre-embolization future liver remnant (FLR) was 28% versus 32% (p < 0.001) for cPVE-HVE and PVE. Post-embolization DH (11.3% versus 9.4%; p = 0.001) and KGR (3.33% versus 2.29%; p < 0.001) were significantly greater for cPVE-HVE over shorter interval (22 versus 28 days; p = 0.007). HAIC was used in 42% (n = 23) of patients before cPVE-HVE and did not impact hypertrophy. Post-hepatectomy outcomes were similar between cPVE-HVE (n = 38) and PVE (n = 250) cohorts. Rates of transfusion (39% versus 40%; p > 0.9), liver failure (7.9% versus 9.2%, p = 0.6), grade 3-5 complications (42% versus 42%, p > 0.9), 90 day all-cause mortality (5.3% versus 3.6%, p = 0.6), and median hospitalization (7 versus 8 days; p = 0.067) were not significantly different.

CONCLUSIONS

cPVE-HVE was associated with greater hypertrophy than PVE alone, with similar post-hepatectomy outcomes. cPVE-HVE after HAIC was safe with similar hypertrophy. Randomized clinical trial evidence is needed to clearly delineate indication for cPVE-HVE and assess postoperative outcomes.

Surgical management, including the role of transplantation, for intrahepatic and peri-hilar cholangiocarcinoma

Intrahepatic and peri-hilar cholangiocarcinoma are life threatening disease with poor outcomes despite optimal treatment currently available (5-year overall survival following resection 20-35%, and <10% cured at 10-years post resection). The insidious onset makes diagnosis difficult, the majority do not have a resection option and the high recurrence rate post-resection suggests that occult metastatic disease is frequently present. Advances in perioperative management, such as ipsilateral portal vein (and hepatic vein) embolisation methods to increase the future liver remnant volume, genomic profiling, and (neo)adjuvant therapies demonstrate great potential in improving outcomes. However multiple areas of controversy exist. Surgical resection rate and outcomes vary between centres with no global consensus on how 'resectable' disease is defined - molecular profiling and genomic analysis could potentially identify patients unlikely to benefit from resection or likely to benefit from targeted therapies. FDG-PET scanning has also improved the ability to detect metastatic disease preoperatively and avoid futile resection. However tumours frequently invade major vasculo-biliary structures, with resection and reconstruction associated with significant morbidity and mortality even in specialist centres. Liver transplantation has been investigated for very selected patients for the last decade and yet the selection algorithm, surgical approach and both value of both neoadjuvant and adjuvant therapies remain to be clarified. In this review, we discuss the contemporary management of intrahepatic and peri-hilar cholangiocarcinoma.

Optimal treatment strategies for borderline resectable liver metastases from colorectal cancer

BACKGROUND

Traditionally, colorectal liver metastases (CRLMs) are divided into "initially resectable" and "initially unresectable." The terminology "borderline resectable" continues to be elusive without any common consensus or definition. This narrative review aims to decode the conundrum of "borderline resectable CRLM (BR-CRLM)" and to discuss optimal treatment strategies.

METHODS

A comprehensive review was performed using Medline/PubMed and Web of Science databases with a search period ending on January 1, 2024. Using PubMed, the terms "CRLM," "BR-CRLM," and "management of BR-CRLM" were searched.

RESULTS

The 2016 European Society for Medical Oncology guidelines defined the term "resectability" in CRLM using the "technical (surgical) criteria" and the "oncologically criteria." These 2 criteria form the basis of defining BR-CRLM. Thus, BR-CRLM can be either technically easy but with unfavorable oncologically criteria or technically difficult with favorable oncologically criteria. Although defining BR-CRLM by incorporating both these criteria seems to be the most logical way forward, there is currently a lot of heterogeneity in the literature. It is generally agreed upon that some form of chemotherapy needs to be administered in BR-CRLM before embarking on surgery. Conversion chemotherapy is used in patients with BR-CRLM in which there is a possibility of resection after effective downsizing. Along with improved effective chemotherapy, great strides have been made in pushing the limits of surgery to achieve resectability in this subset of patients.

CONCLUSION

Advanced surgical techniques and locoregional liver-directed therapies coupled with perioperative chemotherapy with or without targeted therapy have made long-term survival benefit, a reality in patients with BR-CRLM. Thus, the time has come to recognize "BR-CRLM" as a distinct entity.

Transileocolic Portal Vein Embolization Increases Remnant Liver Volume After Major Hepatectomy

BACKGROUND/AIM

Transileocolic portal vein embolization (TIPE) may reduce the risk of liver failure after massive hepatectomy. However, convincing evidence of its usefulness in this regard is yet to be reported. Therefore, this study aimed to investigate the use of TIPE after massive hepatectomy.

PATIENTS AND METHODS

Twelve patients who underwent TIPE were included. Pre- and postoperative liver volumetry was determined using a 3D simulator with computed tomography.

RESULTS

After TIPE, the percent change in total liver volume was 104.0%±13.1% (p=0.08). Conversely, the percent increase in remnant liver volume (ml)/total liver volume (ml) and remnant liver volume (ml)/standard liver volume (ml) was 122.9%±18.6% (p<0.001) and 132.2%±19.6% (p<0.001), respectively. TIPE operation time was 125±84.6 min, with minimal blood loss in all cases. Postoperative hospitalization duration during TIPE was 4.5±2.6 days. No TIPE-related complications occurred in any patient.

CONCLUSION

TIPE is beneficial and safe when preoperative volumetry indicates that the remaining liver volume is inadequate and inoperable.

Transfemoral hepatic vein access in double vein embolization - initial experience and feasibility

BACKGROUND

Hepatic vein embolization in double vein embolization (DVE) can be performed with transhepatic, transjugular or transfemoral access. This study evaluates the feasibility and technical success of using a transfemoral access for the hepatic vein embolization in patients undergoing preoperative to induce hypertrophy of the future liver remnant (FLR).

MATERIAL AND METHODS

Retrospective analysis of single center cohort including 17 consecutive patients. The baseline standardized FLR was 18.2% (range 14.7-24.9). Portal vein embolization was performed with vascular plugs and glue through an ipsilateral transhepatic access. Hepatic vein embolization was performed using vascular plugs. Access for the hepatic vein was either transhepatic, transjugular or transfemoral. Technical success, number of hepatic veins embolized and complications were registered. In addition, volumetric data including degree of hypertrophy (DH) and kinetic growth rate (KGR), and resection data were registered. R: Seven of the 17 patients had transfemoral hepatic vein embolization, with 100% technical success. No severe complications were registered. In the whole cohort, the median number of hepatic veins embolized was 2 (1-6). DH was 8.6% (3.0-19.4) and KGR was 3.6%/week (1.4-7.4), without significant differences between the patients having transfemoral versus transhepatic /transjugular access (p = 0.48 and 0.54 respectively). Time from DVE to surgery was median 4.8 weeks (2.6-33.9) for the whole cohort, with one patient declining surgery, two having explorative laparotomy and one patient having change of surgical strategy due to insufficient growth.

CONCLUSION

Transfemoral access is a feasible option with a high degree of technical success for hepatic vein embolization in patients with small future liver remnants needing DVE.

Cornerstones and divergencies in the implementation and use of liver hypertrophy techniques: results from a nationwide survey for the set-up of the prospective registry

BACKGROUND

The aim of this national survey on liver hypertrophy techniques was to track the trends of their use and implementation in Italy and to detect analogies and heterogeneities among centers.

METHODS

In December 2022, Italian centers with liver resection activity were specifically contacted and asked to fill an online questionnaire composed of 6 sections including a total of 51 questions.

RESULTS

46 Italian centers filled the questionnaire. The proportion of major/total number of liver resections was 27% and the use of hypertrophy techniques was required in 6,2% of cases. The most frequent reason of drop out was disease progression in 58.5% of cases. Most frequently used techniques were PVE and ALPPS with an increasing use of hepatic venous deprivation (HVD). Heterogeneous answers were provided regarding the cutoff values to indicate the need for hypertrophy techniques. Criteria to allocate a patient to different hypertrophy techniques are not standardized.

CONCLUSIONS

The use of hypertrophy techniques is deep-rooted in Italy, documenting the established value of their role in improving resectability rate. While an evolution of techniques is detectable, still significant heterogeneity is perceived in terms of cutoff values, indications and managing protocols.

CIRSE Standards of Practice on Portal Vein Embolization and Double Vein Embolization/Liver Venous Deprivation

This CIRSE Standards of Practice document is aimed at interventional radiologists and provides best practices for performing liver regeneration therapies prior to major hepatectomies, including portal vein embolization, double vein embolization and liver venous deprivation. It has been developed by an expert writing group under the guidance of the CIRSE Standards of Practice Committee. It encompasses all clinical and technical details required to perform liver regeneration therapies, revising the indications, contra-indications, outcome measures assessed, technique and expected outcomes.

Single-Center Retrospective Study Comparing Double Vein Embolization via a Trans-Jugular Approach with Liver Venous Deprivation via a Trans-Hepatic Approach

PURPOSE

To compare safety, technical and clinical outcomes of double vein embolization (DVE) via a trans-jugular approach with liver venous deprivation (LVD) via a trans-hepatic approach.

MATERIALS AND METHODS

A single-center retrospective analysis was conducted on patients undergoing simultaneous portal and hepatic veins embolization in view of a major hepatectomy (June 2019-November 2022). Hepatic vein embolization was performed either by transjugular plug (DVE) or by transhepatic plug followed by glue injection (LVD). Inclusion criteria were availability of pre-procedural CT scan, and availability of CT scans acquired 10 days and 25 days post-procedure. Comparative data included complication rate, fluoroscopy time, dose area product (DAP), Future Liver Remnant volume and function increase (FLR-V and FLR-F increase, respectively) and clinical outcomes.

RESULTS

Thirty-six patients (n = 14 DVE; n = 22 LVD) were included. No baseline significant differences were observed among the two groups. One grade-3 complication (2.8%) was observed in the LVD group; one case of technical failure (2.8%) was observed in the DVE group. Fluoroscopy time and DAP were similar between DVE and LVD (29 ± 17.7 vs. 25 ± 8.2 min, p = 0.97; 105.1 ± 63.5 vs. 143.4 ± 79.5 Gy·cm2, p = 0.15). No differences arose at either time-point in FLR-V increase (46.7 ± 23.1% vs. 48.2 ± 28.2%, 52.9 ± 30.9% vs. 53.2 ± 29%, respectively, p = 0.9). FLR-F increase also did not differ significantly (62.8 ± 55.2 vs. 67.4 ± 57.5, p = 0.9). No differences in drop-out rate from surgery were observed. (28.6% vs. 27.3%, p = 0.93). One case of grade-B post-hepatectomy liver failure (2.8%) was observed in the LVD group.

CONCLUSION

LVD via transhepatic approach and DVE via transjugular approach seem equally safe and effective. Level of Evidence Level 3, Retrospective Cohort Study.

A "cui prodest" evaluation on the development of a minimally invasive liver surgery program: a differential benefit analysis of open and laparoscopic approach for left and right hemihepatectomies

BACKGROUND

The correlation between technical feasibility and short-term clinical advantage provided by laparoscopic over open technique for major hepatectomies is unclear. This monocentric retrospective study investigates the possible differences in the benefit provided by minimally invasive approach between left and right hepatectomy, deepening the concept of differential benefit in the setting of anatomical major resections.

METHODS

All hemihepatectomies performed from January 2004 to December 2021 were identified in the institutional database. A propensity score method was used to match minimal invasive (MILS) and open pairs in the left hemihepatectomies (LH) and right hemihepatectomies (RH) groups with a 1:1 ratio to adjust any potential selection bias. The differential benefit for left and right hepatectomy provided by laparoscopic over open technique was evaluated in a pure analysis (i.e., including cases converted to open) and a risk-adjusted analysis (i.e., after excluding open conversion from the laparoscopic series).

RESULTS

The analysis of the risk-adjusted differential benefit demonstrated better result of the MILS in the RH group than in the LH group, in terms of blood loss (∆ blood loss - 150 and - 350, respectively; differential benefit: 200 mL, p < 0.05), morbidity (∆ rate of morbidity - 11.3% and - 18.1%, respectively; differential benefit: 6.8%, p < 0.05) and length of stay, LOS (∆ LOS - 1 day and - 3 days, respectively; differential benefit: 2 days, p < 0.05).

CONCLUSION

While MILS is associated with improved clinical outcomes both in left and right hepatectomy procedures, the greater advantage provided by laparoscopy was documented in patients undergoing right hepatectomy, i.e. for more technically demanding procedures. A MILS program should include the broadest range of liver resections to ensure the full benefits of the laparoscopic technique.

The Effect of Microwave and Radiofrequency Ablation (MWA/RFA) on Liver Volume in Patients with Primary and Secondary Liver Tumours: A Retrospective Analysis

PURPOSE

It is known that thermal liver ablation can induce liver hypertrophy. However, exact impact in liver volume remains unclear. The aim of this study is to assess the influence of radiofrequency or microwave ablation (RFA/MWA) on liver volume in patients with primary and secondary liver lesions. Findings can be relevant in assessing the potential extra benefit of thermal liver ablation in preoperatively performed liver hypertrophy inducing procedures, such as portal vein embolization (PVE).

METHODS

Between January 2014-May 2022, 69 invasive treatment naïve patients with primary (n = 43) or secondary/metastatic (n = 26) liver lesions (in all segments, except in segments II/III) treated percutaneously by RFA/MWA were included. Total liver volume (TLV), segment II + III volume (serving as "distant liver volume"), ablation zone volume and absolute liver volume (ALV, calculated by subtracting the ablation zone volume from the TLV) were the study outcomes.

RESULTS

ALV in patients with secondary liver lesions increased to a median percentage of 106.87% (IQR = 99.66-113.03%, p = 0.016), volume of segments II/III increased to a median percentage of 105.81% (IQR = 100.06-115.65%, p = 0.003). ALV and segments II/III in patients with primary liver tumours remained stable, with a median percentage of 98.72% (IQR = 92.99-108.35%, p = 0.856) and 100.43% (IQR = 92.85-109.41%, p = 0.699), respectively.

CONCLUSION

In patients with secondary liver tumours, ALV and segments II/III increased after MWA/RFA by an average of approximately 6%, while ALV in patients with primary liver lesions remained unchanged. Besides the curative intent, these findings indicate the potential added benefit of thermal liver ablation on FLR hypertrophy inducing procedures in patients with secondary liver lesions.

LEVEL OF EVIDENCE

Level 3, non-controlled retrospective cohort study.

Optimizing the future liver remnant: Portal vein embolization, hepatic venous deprivation, and associating liver partition and portal vein ligation for staged hepatectomy

Preservation of an adequate future liver remnant is paramount when planning any major liver resection and is of particular concern in the setting of bilateral colorectal liver metastases. Procedures including portal vein embolization and hepatic venous deprivation for one- or two-stage hepatectomy, and associating liver partition and portal vein ligation for staged hepatectomy have been developed to enable curative-intent hepatectomy for colorectal liver metastases in patients with an initially insufficient future liver remnant.

Influence of cholestasis on portal vein embolization-induced hypertrophy of the future liver remnant

PURPOSE

In the pre-clinical setting, hepatocellular bile salt accumulation impairs liver regeneration following partial hepatectomy. Here, we study the impact of cholestasis on portal vein embolization (PVE)-induced hypertrophy of the future liver remnant (FLR).

METHODS

Patients were enrolled with perihilar cholangiocarcinoma (pCCA) or colorectal liver metastases (CRLM) undergoing PVE before a (extended) right hemihepatectomy. Volume of segments II/III was considered FLR and assessed on pre-embolization and post-embolization CT scans. The degree of hypertrophy (DH, percentual increase) and kinetic growth rate (KGR, percentage/week) were used to assess PVE-induced hypertrophy.

RESULTS

A total of 50 patients (31 CRLM, 19 pCCA) were included. After PVE, the DH and KGR were similar in patients with CRLM and pCCA (5.2 [3.3-6.9] versus 5.7 [3.2-7.4] %, respectively, p = 0.960 for DH; 1.4 [0.9-2.5] versus 1.9 [1.0-2.4] %/week, respectively, p = 0.742 for KGR). Moreover, pCCA patients with or without hyperbilirubinemia had comparable DH (5.6 [3.0-7.5] versus 5.7 [2.4-7.0] %, respectively, p = 0.806) and KGR (1.7 [1.0-2.4] versus 1.9 [0.8-2.4] %/week, respectively, p = 1.000). For patients with pCCA, unilateral drainage in FLR induced a higher DH than bilateral drainage (6.7 [4.9-7.9] versus 2.7 [1.5-4.2] %, p = 0.012). C-reactive protein before PVE was negatively correlated with DH (ρ = - 0.539, p = 0.038) and KGR (ρ = - 0.532, p = 0.041) in patients with pCCA.

CONCLUSIONS

There was no influence of cholestasis on FLR hypertrophy in patients undergoing PVE. Bilateral drainage and inflammation appeared to be negatively associated with FLR hypertrophy. Further prospective studies with larger and more homogenous patient cohorts are desirable.

Resectability of bilobar liver tumours after simultaneous portal and hepatic vein embolization versus portal vein embolization alone: meta-analysis

BACKGROUND

Many patients with bi-lobar liver tumours are not eligible for liver resection due to an insufficient future liver remnant (FLR). To reduce the risk of posthepatectomy liver failure and the primary cause of death, regenerative procedures intent to increase the FLR before surgery. The aim of this systematic review is to provide an overview of the available literature and outcomes on the effectiveness of simultaneous portal and hepatic vein embolization (PVE/HVE) versus portal vein embolization (PVE) alone.

METHODS

A systematic literature search was conducted in PubMed, Web of Science, and Embase up to September 2022. The primary outcome was resectability and the secondary outcome was the FLR volume increase.

RESULTS

Eight studies comparing PVE/HVE with PVE and six retrospective PVE/HVE case series were included. Pooled resectability within the comparative studies was 75 per cent in the PVE group (n = 252) versus 87 per cent in the PVE/HVE group (n = 166, OR 1.92 (95% c.i., 1.13-3.25)) favouring PVE/HVE (P = 0.015). After PVE, FLR hypertrophy between 12 per cent and 48 per cent (after a median of 21-30 days) was observed, whereas growth between 36 per cent and 67 per cent was reported after PVE/HVE (after a median of 17-31 days). In the comparative studies, 90-day primary cause of death was similar between groups (2.5 per cent after PVE versus 2.2 per cent after PVE/HVE), but a higher 90-day primary cause of death was reported in single-arm PVE/HVE cohort studies (6.9 per cent, 12 of 175 patients).

CONCLUSION

Based on moderate/weak evidence, PVE/HVE seems to increase resectability of bi-lobar liver tumours with a comparable safety profile. Additionally, PVE/HVE resulted in faster and more pronounced hypertrophy compared with PVE alone.