Is the Use of iFR for the Deferral of Left Main Coronary Artery Lesions Safe?

Deferral of left main coronary artery lesions using instantaneous wave-free ratio (iFR) seems to be safe. At the least, patients with deferred lesions had similar long-term prognosis to that of patients who underwent revascularization based on that same indicator.

Left main coronary artery lesions were universally excluded from studies including medical treatment among the therapeutic alternatives.

As a consequence of Yusuf’s work published in The Lancet in 1994 and the CASS Registry published in Circulation the following year, there are almost no new studies randomizing left main coronary artery lesions >50% to medical treatment. Both works showed that the mortality rate for patients randomized to medical treatment was twice as high as for patients who underwent surgery.

A 50% visual assessment required more precision: its underestimation doubles mortality at 5 years and its overestimation entails a trip to the OR for a patient who does not need surgery.

This is when coronary intravascular ultrasound (IVUS) emerged as arbiter and the LITRO study (J Am Coll Cardiol 2011;58:351-8) divided the waters more clearly with a minimal luminal area of 6 mm2.

Read also: Optimal Intervention Timing for NSTEMI with No Antiaggregant Pre-Treatment.

This criterion divided patients for many years. However, new questions emerged. For starters, 6 mm2 is an absolute number; consequently, a small left main coronary artery with a mild lesion might meet the revascularization criterion, while a large-diameter left main coronary artery with a clearly severe lesion could still have a 6-mm2 minimal luminal area.

This work proposes a new arbiter: iFR.

This multicenter observational study included 314 patients with left main coronary artery lesions, among whom 163 (51.9%) were deferred and 151 (48.1%) were revascularized based on an iFR cutoff of 0.89.

Read also: Multiple vs. Culprit vessel MI in Cardiogenic Shock: Anything New?

The primary endpoint was a composite of death, non-fatal infarction, and ischemia-driven revascularization. The secondary endpoints were each individual component of the primary endpoint and also cardiac death.

After 30 months of follow-up, the primary endpoint occurred in 9.2% of deferred patients and in 14.6% of revascularized patients (p = 0.26). There were no significant differences in the individual components either: 3.7% vs. 4.6% for all-cause death; 1.2% vs. 2% for cardiac death; 2.5% vs. 5.3% for non-fatal infarction; 4.3% vs. 5.3% for target-lesion revascularization.

Conclusion

Deferring left main coronary artery lesions based on iFR seems safe, and deferred and revascularized patients appear to have a similar long-term prognosis.

Original Title: Safety of Revascularization Deferral of Left Main Stenosis Based on Instantaneous Wave-Free Ratio Evaluation.

Reference: Takayuki Warisawa et al. J Am Coll Cardiol Intv 2020, article in press. https://doi.org/10.1016/j.jcin.2020.02.035. 

We are interested in your opinion. Please, leave your comments, thoughts, questions, etc., below. They will be most welcome.