When can computed tomography-fissure analysis replace Chartis collateral ventilation assessment in the prediction of patients with emphysema who might benefit from endobronchial valve therapy?

Abstract

A best evidence topic in thoracic surgery was written according to a structured protocol. The question addressed was when can computed tomography-fissure analysis replace Chartis collateral ventilation assessment in the prediction of patients with emphysema who might benefit from endobronchial valve therapy? Twelve papers were chosen to answer the question. The authors, date, journal, country of publication and study type; patient group studied; relevant outcomes and results of these papers were tabulated. Five studies retrospectively compared the prognostic value of 2 methods. They found that when computed tomography-fissure analysis showed an intact fissure more than 95%, both methods were equivalent in correctly predicting a positive response to valve therapy. Concordant results were found in two-thirds of patients, and the additional evaluation with Chartis did not confer a significant advantage. Yet the increasing cost and time to procedure, the different ranges of Chartis findings patterns not correlated with lung volume reduction and the unfeasibility of the measurements (reported in 6–17% of the most series) due to difficult anatomy are additional limitations for its use. Conversely, in patients with fissure integrity between 75% and 90%, Chartis assessment could improve the patient selection, because the computed tomography-fissure analysis alone is unable to predict a successful treatment. In this situation, Chartis had a 31% ability to predict those patients who can be successfully treated. In BeLieVer-HIfi Study, post hoc analysis revealed that the additional use of Chartis for patient selection significantly improved outcomes. Similarly, STELVIO, LIVE and IMPACT studies, where only patients with complete fissure and negative Chartis measurement were treated, showed significant benefits after valve treatment. Finally, in patients with fissure integrity below 75%, the negative predictive value for lobar atelectasis is 100%. Thus, in these patients, it could be futile even considering a Chartis assessment.

INTRODUCTION

A best evidence topic was constructed according to a structured protocol fully described in the ICVTS [1].

THREE-PART QUESTION

In [patients with severe emphysema therapy] is [computed tomography (CT)-fissure analysis] or [Chartis collateral ventilation (CV) assessment] the best for [predicting a successful placement of an endobronchial valve]?

CLINICAL SCENARIO

A patient with severe emphysema and unfit for surgery is referred to your attention for endoscopic lung volume reduction (LVR). The heterogeneity of the disease is mainly localized at left upper lobe, and the patient fulfils the criteria for an endobronchial valve for emphysema according to the Endobronchial Valve for Emphysema Palliation Trial (VENT) criteria [2]. You ask for a quantitative CT-fissure integrity score, and the oblique fissure has a score of 88% integrity. The patient asks you what the chance is with your treatment and also your theatre staff are asking whether you want to also perform an intraoperative Chartis assessment before the placement of the valve.

SEARCH STRATEGY

Medline 1990 to January 2017 using OVID interface: [endobronchial valve] AND [lung volume reduction] AND [emphysema] AND [Chartis Collateral ventilation] OR [CT fissure analysis]. Finally, a hand search was performed to search references from the retrieved study.

SEARCH OUTCOME

One hundred and fifty-five papers were found using the reported search strategy. Twelve papers (Table 1) were identified that provided the most applicable evidence to answer the question.

RESULTS

Herth et al. [3] prospectively evaluated Chartis CV in 80 patients undergoing endobronchial valve (EBV) therapy. CV− (n = 51) vs CV+ patients (n = 29) had higher incidence of target lobe volume reduction (TLVR) ≥350 ml (71% vs 17%) and an improvement in forced expiratory volume in 1 s (FEV1%) (16 ± 22 vs 1 ± 15; P = 0.0013), in 6-min walking test (6MWT) (24 vs 10; P > 0.05) and in St. George’s Respiratory Questionnaire (−10 vs −5; P > 0.05). Chartis assessment was impracticable in 7% of cases.

Reymond et al. [4] retrospectively evaluated the role of CT-fissure assessment to predict CV in 30 patients. In 5 (17%) patients, Chartis assessment was unfeasible. Twenty-five patients were included, and a total of 37 target lobes were assessed. Both tests were concordant in 73% of cases. CT-fissure assessment was highly sensitive (95%) but not specific (44%) for predicting CV. CV was present in 20 of 29 (69%) target lobes with a different grade of fissural defect and in only 1 of 8 (12%) target lobes with complete fissures.

Gompelmann et al. [5] retrospectively compared the predictive value of Chartis CV and CT-fissure analysis to predict TLVR ≥350 ml in 69 patients treated with EBV. Chartis and CT-fissure analysis presented similar diagnostic accuracy (74% vs 77%, respectively). Discordant results were found in 22 (31.9%) cases.

Davey et al. [6] conducted a single-centre randomized controlled trial (RCT), where 50 patients with heterogeneous emphysema and a target lobe with intact interlobar fissure (BeLieVeR-HIFi Study) were randomized to receive EBV (n = 25) or sham valve placement (n = 25). All patients also underwent Chartis assessment that was unfeasible in 12% of cases. Treated group versus control group showed significant improvement in FEV1% (20.9; P = 0.0326) and in 6MWT (33; P = 0.012). Four (17%) patients were CV+, despite the presence of intact fissures. Post hoc analysis revealed that the additional use of Chartis for patient selection could improve outcomes.

Schumann et al. [7] retrospectively compared the predictive value of Chartis CV and CT-fissure analysis to predict TLVR ≥350 ml in 33 of 146 emphysematous patients treated with EBV. Chartis and CT-fissure analysis presented similar sensitivity (88.9% vs 77.8%) and specificity (66.7% vs 73.3%). Discordant results were found in 11 (33.4%) of 33 cases.

Gesierich et al. [8] retrospectively evaluated 92 patients undergoing Chartis evaluation. Four different Chartis findings (CV−/CV+/collapse phenomenon/unclear) were found and correlated with CT-fissure analysis. In CV− patients (n = 46), 34 patients had lobar atelectasis; of these, 31 patients had fissure integrity showing a comparable predictive value of both methods. In collapse phenomenon patients (n = 20), 11 patients with fissure integrity were responders. Chartis assessment was unfeasible in 6.5% of cases.

Klooster et al. [9] conducted a single-centre RCT (Stelvio Study), where 68 patients with severe emphysema, Chartis CV− and CT-fissure integrity were randomized to receive EBV (n = 34) or medical therapy (n = 34). Treated group versus control group showed significant LVR (−0.83; P < 0.001) and improvement in FEV1% (17.8; P = 0.001), in 6MWT (74; P < 0.001) and in St. George’s Respiratory Questionnaire (−14.7; P < 0.001).

Koster et al. [10] retrospectively evaluated the prognostic value of CT-fissure analysis and Chartis CV to predict TLVR ≥350 ml. High-resolution CT analysis and Chartis had similar accuracy (80.6% vs 83.3%, respectively); combining both methods in patients with incomplete fissure, the accuracy increased to 89.5%.

Herzog et al. [11] retrospectively evaluated 406 Chartis measurements in 166 patients and described 4 different findings (CV−/CV+/low flow/low plateau). Patients with CV− target lobe or low flow target lobe and ipsilateral adjacent CV− lobe had a significant improvement in FEV1% (P < 0.05), vital capacity (VC) (P < 0.05) and significant TLVR (P < 0.05) after valve insertion. Chartis assessment was unfeasible in 10% of cases.

de Oliveira et al. [12] retrospectively evaluated the prognostic value of CT-fissure integrity in 38 of 108 emphysematous patients undergoing EBV therapy. The positive predictive values for TLVR ≥350 ml were 83.9%, 70% and 90.5% for fissure integrity ≥75%, fissure integrity between 75% and 90% and fissure integrity >90%, respectively. The negative predictive value in case of fissure integrity <75% was 100%.

Skowasch et al. [13] conducted a multicentre RCT (LIVE Study), where 498 patients with severe emphysema were selected for EBV therapy with Chartis. Compared with the baseline value, a significant LVR (−0.42; P < 0.0001) and improvement in FEV1% (11.9; P < 0.0001), forced vital capacity (12.15%; P < 0.0001) and modified medical research council dyspnea scale (mMRC scale) (−0.49; P < 0.0001) were observed. Chartis assessment was unfeasible in 12.7% of cases.

Valipour et al. [14] conducted a multicentre RCT (IMPACT Study), where 93 patients with severe homogeneous emphysema were randomized (1:1) to receive EBV (n = 43) or medical therapy (n = 50). CV+ patients (n = 17) were excluded. Treated group versus control group showed significant improvement in LVR (−0.48; P = 0.001), FEV1% (17.0; P < 0.001), 6MWT (40; P = 0.002) and St. George’s Respiratory Questionnaire (−9.64; P < 0.001).

CLINICAL BOTTOM LINE

This analysis shows that in patients with a grade of CT-fissure integrity ≥95% [5, 7, 8], valves can be directly implanted, whereas in patients with fissure integrity between 75% and 90% [4, 10] to confirm the absence of CV, Chartis assessment could be required before proceeding with valve implant. Finally, in patients with fissure integrity below 75%, the negative predictive value for lobar atelectasis is 100% [12]. Thus, in these cases, it could be futile even considering a Chartis assessment.

Conflict of interest: none declared.

REFERENCES