Safety of intermediate left main stenosis revascularization deferral based on fractional flow reserve and intravascular ultrasound: A systematic review and meta-regression including 908 deferred left main stenosis from 12 studies.

Background: Current guidelines recommend intravascular ultrasound (IVUS) or fractional flow reserve (FFR) to decide upon ambiguous left main (LM) disease. However, no study has compared the safety of LM revascularization deferral based on FFR or IVUS.

Methods: MEDLINE/PubMed was systematically screened for studies reporting on deferred treatment of angiographically ambiguous LM based upon FFR or IVUS evaluation. Baseline, angiographic and outcome data were appraised and pooled separately for each strategy according to random-effect models with inverse-variance weighting.

Results: A total of 908 LM stenoses from 7 FFR and 5 IVUS studies were included with median follow-up of 29.0 and 31.5 months respectively. Per year of follow-up occurrence of overall MACE were 5.1% in FFR group and 6.4% in IVUS group while death, myocardial infarction, LM revascularization were respectively 2.6%, 1.5% and 1.8% vs. 3.0%, 0.5% and 2.2%. Meta-regression analysis suggested the influence of a distal LM stenosis on MACE in FFR group (β = 0.06, p = 0.01) and age in IVUS group (β = 0.4, p = 0.001). In individual studies several independent predictors of MACE were identified including use of lower doses of intracoronary adenosine (OR 1.39, p = 0.04) in FFR group and plaque burden (OR 1.34, p = 0.025), number of other diseased vessels (OR 1.39, p = 0.04) and any untreated stenosis (OR 3.80; p = 0.037) in IVUS- studies.

Conclusions: Deferring LM intermediate stenosis on the basis of FFR or IVUS showed an acceptable and similar risk of events in a mid-term follow-up. Conversely, several different variables related to each technique showed an interaction on outcome.