WASHINGTON – A new study shows that when compared with patients without intermediate left main coronary artery disease, those with intermediate left main disease have greater risk of cardiovascular events. The findings of the ISCHEMIA trial sub study were presented during the SCAI 2020 Scientific Sessions Virtual Conference as featured clinical research.

The presence of left main disease (LMD) typically provokes both emotional and evidence-based concerns that apart from trials done in the 1980s, patients with left main disease have been excluded from trials of revascularization vs. medical therapy. ISCHEMIA also excluded patients with left main disease, although patients with intermediate left main disease (25-49%) were allowed. The outcomes of these patients and the effect of invasive vs. conservative strategy has not been explored before.  

In the study, randomized ISCHEMIA trial participants who underwent coronary computed tomography angiography (CCTA) at baseline were categorized into those with (25-49%) and without (<25%) intermediate LMD as determined by a core lab. Patients with LMD ≥50%, those with prior coronary artery bypass graft surgery (CABG), and those with non-evaluable or missing data on LM stenosis were excluded. Both clinical and quality of life (QoL) outcomes in those with and without intermediate LMD were compared, as well as outcomes of participants randomized to an initial invasive versus conservative strategy.

ISCHEMIA randomized 5,179 participants to an initial invasive or conservative strategy; those who underwent coronary CCTA comprise the LMD sub study cohort. Among the 3,913 participants who underwent CCTA, 3,699 satisfied the inclusion criteria. Of these participants, 962 (26%) had intermediate LMD and 2,737 (74%) did not. Among invasive strategy participants with intermediate LMD, 7.0% had significant LM stenosis on invasive angiography. The primary outcome event rate was significantly higher in those with intermediate LMD as compared to those without intermediate LMD (adjusted HR=1.31; 95% CI 1.06 to 1.61; P=0.0123).

“Our study showed that when compared with patients without intermediate left main disease, those with intermediate left main disease had worse outcomes,” said Sripal Bangalore, MD, FSCAI, director of the Cardiac Catheterization Laboratory at Bellevue Hospital and lead author of the study. “However, there was no treatment interaction such that the outcomes with invasive vs. conservative were similar whether or not the patient had intermediate left main disease on CCTA.”

 Abstract #11656 “Outcomes with Intermediate Left Main Disease on Coronary CT Angiography in the ISCHEMIA trial (ISCHEMIA Intermediate LM Substudy).” SCAI 2020 Scientific Sessions Virtual Conference, May 14-16, 2020.