Intermediate LMD linked to worse outcomes
After the researchers adjusted for baseline differences between the two groups in overall substudy cohort, they found that intermediate LMD severity was an independent predictor of the primary composite endpoint of cardiovascular death, MI, hospitalization for unstable angina, heart failure, and resuscitated cardiac arrest (hazard ratio, 1.31; P = .0123); cardiovascular death/MI/stroke (HR, 1.30; P = .0143); procedural primary MI (HR, 1.64; P = .0487); heart failure (HR, 2.06; P = .0239); and stroke (HR, 1.82, P = .0362).
“We then looked to see if there is a treatment difference, a treatment effect based on whether patients had intermediate LMD,” Dr. Bangalore said. “Most of the P values were not significant. The results are very consistent with what we saw in the main analysis: not a significant difference between invasive and conservative strategy. We do see some differences, though. An invasive strategy was associated with a significantly higher risk of procedural MI [2.9% vs. 1.5%], but a significantly lower risk of nonprocedural MI [–6.4% vs. –2%].”
Dr. Bangalore added that there was significant benefit of the invasive strategy in reducing angina and improving quality of life based on the Seattle Angina Questionnaire-7. “This result was durable up to 48 months of follow-up, whether the patient had intermediate left main disease or not. These results were dependent on baseline angina status. The benefit of invasive strategy was mainly in patients who had daily, weekly, and monthly angina, and no benefit in patients with no angina; there was no interaction based on intermediate left main status.”
Dr. Bangalore emphasized that the original ISCHEMIA trial excluded patients with severe left main disease by design. “But patients with intermediate left main disease in ISCHEMIA tended to have a greater extent of coronary artery disease, indicating greater atherosclerotic burden. I don’t think that’s any surprise. They had a worse prognosis with higher risk of cardiovascular events but similar quality of life, including angina-specific quality of life.”
The key clinical message, he said, is that patients with intermediate LMD face an increased risk of cardiovascular events. “I think we have to be aggressive in trying to reduce their risk with medical therapy, etc.,” he said. “If they are symptomatic, ISCHEMIA tells us that patients have two options. They can choose an invasive strategy, because clearly there is a benefit. You have a significant benefit at making you feel better and potentially reducing the risk of spontaneous MI over a period of time. Or, you can try medical therapy first. If you do see some left main disease, it’s showing the general burden of atherosclerosis disease in those patients. I think that’s the critical message, that we have to be very aggressive with these patients.”
A call for more imaging studies
An invited panelist, Timothy D. Henry, MD, said that the results of the ISCHEMIA substudy should stimulate further research. “With an intermediate lesion, clearly the interventional group did better, and it wasn’t symptom related,” said Dr. Henry, medical director of the Carl and Edyth Lindner Center for Research and Education at the Christ Hospital in Cincinnati. “So even if you do medical therapy, you’re not going to really find it out. In my mind, this should stimulate us to do more imaging of the left main that are moderate lesions, and follow this up as an independent study. I think this is a really important finding.”
ISCHEMIA was supported by grants from the National Heart, Lung, and Blood Institute. Dr. Bangalore disclosed that he is a member of the advisory board and/or a board member for Meril, SMT, Pfizer, Amgen, Biotronik, and Abbott. He also is a consultant for Reata Pharmaceuticals.
SOURCE: Bangalore S et al. SCAI 2020, Abstract 11656.