Left main bifurcation stenting: impact of residual ischaemia on cardiovascular mortality

Abstract

Aims: The present study sought to determine the rate and prognostic implications of post-procedural physiologically significant residual ischemia according to Murray law-based quantitative flow ratio (μQFR) after left main (LM) bifurcation percutaneous coronary intervention (PCI).

Methods and results: Consecutive patients undergoing LM bifurcation stenting at a large tertiary care center between January 2014 and December 2016 with available post-PCI μQFR were included. Physiologically significant residual ischemia was defined by post-PCI μQFR values ≤0.80 in the left anterior descending (LAD) or left circumflex artery (LCX). The primary outcome was 3-year cardiovascular death. The major secondary outcome was 3-year bifurcation-oriented composite endpoint (BOCE). Among 1170 included patients with analyzable post-PCI μQFR, 155 (13.2%) had residual ischemia in either LAD or LCX. Patients with vs. those without residual ischemia had a higher risk of 3-year cardiovascular mortality [5.4% vs. 1.3%; adjusted hazard ratio (HR) 3.20, 95% confidence interval (CI): 1.16-8.80]. The 3-year risk of BOCE was significantly higher in the residual ischemia group (17.8% vs. 5.8%; adjusted HR 2.79, 95% CI: 1.68-4.64), driven by higher incidence of the composite of cardiovascular death and target bifurcation-related myocardial infarction (14.0% vs. 3.3%; adjusted HR 4.06, 95% CI: 2.22-7.42). A significant, inverse association was observed between continuous post-PCI μQFR and the risk of clinical outcomes (per 0.1 μQFR decrease, HR of cardiovascular death 1.27, 95% CI: 1.00-1.62; HR of BOCE 1.29, 95% CI: 1.14-1.47).

Conclusion: After angiographically successful LM bifurcation PCI, residual ischemia assessed by μQFR was identified in 13.2% of patients and was associated with higher risk of 3-year cardiovascular death, indicating the superior prognostic value of post-PCI physiological assessment.

Keywords: Cardiovascular death; Left main coronary artery disease; Percutaneous coronary intervention; Quantitative flow ratio; Residual ischemia.

Structured Graphical Abstract

Physiologically significant residual ischemia after LM bifurcation stenting. Among 1,170 included patients undergoing angiographically successful LM bifurcation PCI with analyzable post-PCI μQFR, 155 (13.2%) had residual ischemia in either LAD or LCX which was associated with a significantly higher risk of 3-year adverse cardiac events. The post-PCI μQFR demonstrated a continuous and inverse relationship between its numeric value and clinical events. Mismatch between post-PCI physiological and anatomical assessment for significant stenoses was identified in over 15% of patients, in whom post-PCI μQFR-based physiological assessment showed superior prognostic value for 3-year clinical outcomes. BOCE, bifurcation-oriented composite endpoint; CABG, coronary artery bypass grafting; CI, confidence interval; CV, cardiovascular; DS, diameter stenosis; HR, hazard ratio; LAD, left anterior descending artery; LCX, left circumflex artery; LM, left main; PCI, percutaneous coronary intervention; TB, target bifurcation; μQFR, Murray law-based quantitative flow ratio.

Figure 1

Study flowchart. Among 1170 patients with analyzable post-percutaneous coronary intervention Murray law-based quantitative flow ratio assessments, 155 (13.2%) with abnormal post-percutaneous coronary intervention Murray law-based quantitative flow ratio in either left anterior descending or left circumflex artery, in spite of “successful” percutaneous coronary intervention by angiographic criteria, were attributed to residual ischemia group. LAD, left anterior descending; LCX, left circumflex artery; LM, left main; RVD, reference vessel diameter; STEMI, ST-segment elevation myocardial infarction; NSTEMI, non-ST-segment elevation myocardial infarction; PCI, percutaneous coronary intervention; μQFR, Murray law-based quantitative flow ratio.

Figure 2

Distribution of post-percutaneous coronary intervention Murray law-based quantitative flow ratio and 3-year outcomes. (A) Among 1170 patients, 1015 (86.8%) patients had no residual ischemia, 117 (10.0%) had left circumflex artery ischemia alone, 32 (2.7%) had left anterior descending ischemia alone, and 6 (0.5%) had both left anterior descending and left circumflex artery ischemia; (B) cumulative incidence of cardiovascular death and bifurcation-oriented composite endpoint according to left circumflex artery or left anterior descending ischemia after percutaneous coronary intervention. CV, cardiovascular; BOCE, bifurcation-oriented composite endpoint; other abbreviations as in Figure 1.

Figure 3

Time-to-event curves for 3-year clinical outcomes stratified by physiologically significant residual ischemia or residual disease by anatomy. Kaplan–Meier time-to-first event curves showing the 3-year cumulative incidences of cardiovascular death and bifurcation-oriented composite endpoint by physiologically significant residual ischemia (A and B) and residual disease by anatomy (C and D), respectively. BOCE, bifurcation-oriented composite endpoint; CI, confidence interval; CV, cardiovascular; DS, diameter stenosis; HR, hazard ratio; PMI, periprocedural myocardial infarction; other abbreviations as in Figure 1.

Figure 4

Distribution and clinical outcomes by patient-level post-percutaneous coronary intervention minimal Murray law-based quantitative flow ratio^a. ^aDefined as the lower post-percutaneous coronary intervention Murray law-based quantitative flow ratio value in left anterior descending and left circumflex artery. (A and B) Distribution of post-percutaneous coronary intervention minimal Murray law-based quantitative flow ratio; (C and D) Rates of 3-year adverse events in each 0.05 post-percutaneous coronary intervention minimal Murray law-based quantitative flow ratio unit; (E and F) Estimated risks of 3-year adverse events according to continuous post-percutaneous coronary intervention minimal Murray law-based quantitative flow ratio. Abbreviations as in Figure 1.