Analysis of threshold stenosis by multiplanar venogram and intravascular ultrasound examination for predicting clinical improvement after iliofemoral vein stenting in the VIDIO trial.

BACKGROUND: Selecting patients for iliofemoral vein stenting has traditionally relied on the identification and quantification of stenotic lesions with imaging such as multiplanar venography. Recently, intravascular ultrasound (IVUS) imaging has become more available. However, to date, the usefulness of these imaging modalities using the customary >50% treatment threshold for diameter (multiplanar venography) and area (IVUS) stenosis of iliofemoral veins has not been validated prospectively within the context of clinical improvement.

METHODS: The multicenter Venogram Versus Intravascular Ultrasound for Diagnosing and Treating Iliofemoral Vein Obstruction (VIDIO) trial prospectively enrolled 100 symptomatic patients (Clinical Etiologic Anatomic Pathophysiologic [CEAP] classification of 4-6) with suspected iliofemoral venous outflow disease. Venous stenting for presumed significant iliofemoral vein stenosis, based on imaging and clinical findings, was performed on 68 patients. Based on imaging, stenosis was characterized as nonthrombotic in 48 patients and post-thrombotic in 20 patients. Each underwent baseline and poststenting venography and IVUS to compare the diagnostic and clinical usefulness of the tests. The revised Venous Clinical Severity Score was used to assess clinical patient outcome. A >4-point reduction in the revised Venous Clinical Severity Score between baseline and 6 months was used as an indicator of clinically meaningful improvement. Receiver operating characteristic curve analysis was used to determine the optimal diameter and area thresholds for prediction of clinical improvement.

RESULTS: Clinical improvement after stenting was best predicted by IVUS baseline measurement of area stenosis (area under the curve, 0.64; P = .04), with >54% estimated as the optimal threshold of stenosis indicating interventional treatment. With measurement of lumen gain from baseline to after the procedure, the optimal reduction in vein stenosis correlative of later clinical improvement was >41%; IVUS measurement of area stenosis was most predictive (area under the curve, 0.70; P = .004). Venographic measurements of baseline stenosis and stenotic change were not predictive of later improvement. In a 48-patient nonthrombotic subset analysis, IVUS diameter rather than area measurements of baseline stenosis were significantly predictive of clinical success, but indicated a higher optimal threshold of stenosis (>61%) may be necessary.

CONCLUSIONS: This study suggests that IVUS shows significant usefulness at predicting when stenting iliofemoral vein stenosis in patients clinical-etiologic-anatomic-pathophysiologic classification of 4-6 will result in significant symptom improvement. Our findings corroborate the conventional >50% cross-sectional area threshold by IVUS as defining a clinically significant iliofemoral stenosis that, when stented, has significant predictive value for symptom improvement. In nonthrombotic patients, however, a threshold of >61% diameter stenosis by IVUS may better predict clinical improvement.