Background: Several intravascular diagnostic techniques provide detailed information regarding the narrowing (stenosis) of the lumen of coronary arteries. They are increasingly used in addition to angiography during coronary artery stenting.
Purpose: To systematically review the comparative effectiveness of intravascular diagnostic techniques versus angiography alone in patients with coronary artery disease who are undergoing percutaneous coronary interventions for the following objectives: (a) to decide whether a coronary lesion needs to be stented; (b) to guide and optimize stent deployment; (c) to assess whether stent placement was successful; and (d) to evaluate the factors influencing the diagnostic techniques' effect on outcomes.
Data sources:
MEDLINE®, Cochrane Central Register of Controlled Trials, recent conference proceedings, and
Study selection: We included studies of any design and duration of followup, without any language or sample size restriction. We excluded studies that did not directly compare the use of an intravascular diagnostic technique with angiography alone or another intravascular diagnostic technique to decide whether to stent or to guide coronary artery stenting.
Data extraction: We extracted details on study population characteristics and results, and assessed studies for risk of bias. We evaluated therapeutic decisionmaking outcomes, intermediate outcomes, and patient-centered outcomes. We appraised strength of evidence primarily based on studies rated as having a low or medium risk of bias.
Data synthesis: In total, 37 eligible studies evaluated two of the intravascular diagnostic techniques, namely fractional flow reserve (FFR) and intravascular ultrasound (IVUS). There is a moderate strength of evidence (drawn from one randomized controlled trial [RCT] and one nonrandomized study) that the use of FFR, as compared with angiography alone, supports the following: (a) FFR is effective in helping to decide whether intermediate coronary lesions (defined as 50% to 70% stenosis) require stenting; (b) FFR confers a lower risk of the composite endpoint of death or myocardial infarction (MI) or of major adverse cardiac events; and (c) FFR leads to fewer stents implanted and reduces the cost of the procedure. Regarding the comparison of IVUS-guided stenting and stent placement guided by angiography alone, there is a moderate strength of evidence (drawn from 9 RCTs and 22 nonrandomized studies) that supports no significant difference between the two approaches in mortality or MI, but a significant reduction in repeat revascularizations and restenosis with IVUS-guided stenting. There is insufficient evidence concerning the use of intravascular diagnostic techniques immediately after percutaneous coronary interventions to evaluate the success of stenting compared with angiography or for direct comparisons between intravascular diagnostic techniques. There is a moderate strength of evidence (on the basis of one large nonrandomized study) that sex, diabetes mellitus status, lesion length, and reference diameter among those undergoing IVUS- and angiography-guided stent placement had no significant association with major adverse cardiac events or its individual components. There is insufficient evidence to evaluate the comparative effect of intravascular diagnostic techniques other than FFR and IVUS.
Limitations: Studies evaluating FFR and IVUS were limited by incomplete outcome reporting, heterogeneity in outcome definitions, infrequent enrollment of women, and a lack of data on patients with left main coronary artery disease or acute MI. The evidence for FFR was derived from trials that focused on patients with lower grade angina or those with nonischemic intermediate coronary stenosis. The majority of the IVUS trials were conducted before 2000, a particularly important limitation given the rapid pace of technological advancement in this domain.
Conclusions: There is a moderate strength of evidence that the use of FFR (as compared with angiography alone) to decide whether or not to stent an intermediate coronary lesion confers a lower risk of composite endpoint of death or MI, or of major adverse cardiac events; leads to fewer stents being implanted; and reduces procedural costs. There is a moderate strength of evidence that the use of IVUS (as compared with angiography alone) to guide optimal stent placement reduces repeat revascularization and restenosis, but does not affect mortality or MI. Future studies will need to focus on women and on patients with more severe coronary artery disease, and to evaluate longer term (on the order of years) patient outcomes to better appreciate real world effectiveness. Stenting low-risk lesions may lead to additional invasive tests or treatments that could adversely impact long-term outcomes. Further research is also needed to evaluate the use of hybrid and novel intravascular diagnostic techniques.