The Hazardous Longitudinal Heterogeneity of Plaques

Lipid Content Distribution and its Clinical Implication in Patients with Acute Myocardial Infarction-Plaque Erosion: Results from the Prospective OCTAMI Study

AIMS

Plaque erosion (PE) is one of the main plaque phenotypes of acute coronary syndrome (ACS). However, the underlying plaque component and distribution have not been systematically analysed. This study aims to investigate the distribution of lipid and calcium content in culprit lesions assessed by optical coherence tomography (OCT) in patients with PE and explore its relationship with prognosis in a cohort of ST segment elevation myocardial infarction (STEMI) patients.

METHODS

A prospective cohort of 576 patients with STEMI was enrolled in our study. After exclusion, 152 PE patients with clear underlying plaque components were ultimately analysed. The culprit lesion was divided into the border zone, external erosion zone and erosion site in the longitudinal view. Each pullback of the culprit lesions was assessed by 3 independent investigators frame-by-frame, and the quantity and distribution of lipid and calcium components were recorded.

RESULTS

Of the 152 PE patients, lipid and calcium contents were more likely to exist in the external erosion zone than in the other regions. In particular, a high level of lipid content proximal to the erosion site was significantly associated with plaque vulnerability and a higher incidence of MACEs.

CONCLUSION

This study revealed that high level of lipid content in the proximal external erosion zone was related to high-risk plaque characteristics and poor prognosis, which provided a novel method for risk stratification and precise management in patients with plaque erosion.

Fundamental Pathobiology of Coronary Atherosclerosis and Clinical Implications for Chronic Ischemic Heart Disease Management-The Plaque Hypothesis: A Narrative Review

Importance

Recent clinical and imaging studies underscore that major adverse cardiac events (MACE) outcomes are associated not solely with severe coronary obstructions (ischemia hypothesis or stenosis hypothesis), but with the plaque burden along the entire coronary tree. New research clarifies the pathobiologic mechanisms responsible for plaque development/progression/destabilization leading to MACE (plaque hypothesis), but the translation of these insights to clinical management strategies has lagged. This narrative review elaborates the plaque hypothesis and explicates the current understanding of underlying pathobiologic mechanisms, the provocative destabilizing influences, the diagnostic and therapeutic implications, and their actionable clinical management approaches to optimize the management of patients with chronic coronary disease.

Observations

Clinical trials of management strategies for patients with chronic coronary artery disease demonstrate that while MACE rate increases progressively with the anatomic extent of coronary disease, revascularization of the ischemia-producing obstruction does not forestall MACE. Most severely obstructive coronary lesions often remain quiescent and seldom destabilize to cause a MACE. Coronary lesions that later provoke acute myocardial infarction often do not narrow the lumen critically. Invasive and noninvasive imaging can identify the plaque anatomic characteristics (plaque burden, plaque topography, lipid content) and local hemodynamic/biomechanical characteristics (endothelial shear stress, plaque structural stress, axial plaque stress) that can indicate the propensity of individual plaques to provoke a MACE.

Conclusions and Relevance

The pathobiologic construct concerning the culprit region of a plaque most likely to cause a MACE (plaque hypothesis), which incorporates multiple convergent plaque features, informs the evolution of a new management strategy capable of identifying the high-risk portion of plaque wherever it is located along the course of the coronary artery. Ongoing investigations of high-risk plaque features, coupled with technical advances to enable prognostic characterization in real time and at the point of care, will soon enable evaluation of the entire length of the atheromatous coronary artery and broaden the target(s) of our therapeutic intervention to include all regions of the plaque (both flow limiting and nonflow limiting).

Preemptive percutaneous coronary intervention for coronary artery disease: identification of the appropriate high-risk lesion

PURPOSE OF REVIEW

Management of patients with coronary artery disease (CAD) has been based on identification of a coronary obstruction causing ischemia and performing a revascularization procedure to reduce that ischemia, with the goal of thereby preventing subsequent major adverse cardiac events (MACEs) in that vascular territory. Recent investigations demonstrate that preemptive percutaneous coronary intervention (PCI) of nonculprit coronary lesions (NCLs) that may not cause ischemia in patients with ST-segment elevation myocardial infarction (STEMI) reduces MACE. In this review, we focus on preemptive PCI, discuss its mechanistic benefits and speculate on its potential value for other coronary syndromes.

RECENT FINDINGS

The COMPLETE trial in STEMI patients treated with primary PCI demonstrated that preemptive PCI of NCL obstructions, which may not cause ischemia, but often exhibit high-risk OCT plaque characteristics, reduced cardiovascular death or nonfatal myocardial infarction. Reduction in MACE from preemptive PCI of NCL was similar for lesions confirmed to cause ischemia (fractional flow reserve <0.80) and for lesions that were only visually assessed to have luminal obstruction at least 70%.The ISCHEMIA trial in patients with stable CAD and moderate/severe ischemia demonstrated that MACE risk increased progressively with more extensive atherosclerosis, but that performing PCI of ischemia-producing lesions did not reduce MACE. Adverse cardiac events likely originated in high-risk plaque areas not treated with PCI.

SUMMARY

In STEMI patients, preemptive PCI of high-risk NCL that may not cause ischemia improves long-term MACE. In stable CAD patients, MACE increases as the atherosclerotic burden increases, but PCI of the ischemia-producing lesion itself does not improve outcomes compared with optimal medical therapy. Adverse events likely originate in high-risk plaque areas that are distinct from ischemia-producing obstructions. Identification of highest-risk atherosclerotic lesions responsible for future MACE may provide an opportunity for preemptive PCI in patients with a variety of coronary syndromes.