Intermediate coronary artery stenosis: evidence-based decisions in interventions to avoid the oculostenotic reflex

The uric acid/HDL-C ratio may predict significant coronary stenosis in moderate left main coronary artery lesions: an intravascular ultrasonography study

BACKGROUND

There may be severe difficulties in determining the severity of LMCA (left main coronary artery) lesions. The use of intravascular ultrasound (IVUS) facilitates decisions about lesion severity in these patients. The aim of this study was to investigate the relationship between the UHR (uric acid to HDL-C ratio) and lesion severity in patients who underwent LMCA IVUS.

METHODS

This study included 205 patients with ICS (intermediate coronary stenosis) in the LMCA who underwent IVUS. In the IVUS measurements of these patients, the plaque burden (PB) and the minimal lumen area (MLA) showing lesion severity were measured.

RESULTS

The patients were separated into two groups according to plaque burden (< 65% and ≥ 65%). The UHR was significantly greater in the high plaque burden group (479.5 vs. 428.6, P = 0.001). When the patients were separated into two groups according to the MLA (< 6mm2 and ≥ 6mm2), the UHR was determined to be significantly greater in the group with low MLA (476.8 vs. 414.9, P < 0.001). In the ROC analysis performed according to the MLA and plaque burden values, the UHR cutoff value of 450 was found to have similar sensitivity and the same specificity for both parameters.

CONCLUSIONS

The results of this study suggested that there is a relationship between UHR and MLA < 6mm2 and plaque burden ≥ 65%, which are independently evaluated as critical in IVUS, and this could predict anatomically significant lesions in patients with a moderate degree of LMCA stricture.

The assessment of intermediate coronary lesions using intracoronary imaging

Intermediate coronary artery stenosis, defined as visual angiographic stenosis severity of between 30-70%, is present in up to one quarter of patients undergoing coronary angiography. Patients with this particular lesion subset represent a distinct clinical challenge, with operators often uncertain on the need for revascularization. Although international guidelines appropriately recommend physiological pressure-based assessment of these lesions utilizing either fractional flow reserve (FFR) or quantitative flow ratio (QFR), there are specific clinical scenarios and lesion subsets where the use of such indices may not be reliable. Intravascular imaging, mainly utilizing intravascular ultrasound (IVUS) and optical coherence tomography (OCT) represents an alternate and at times complementary diagnostic modality for the evaluation of intermediate coronary stenoses. Studies have attempted to validate these specific imaging measures with physiological markers of lesion-specific ischaemia with varied results. Intravascular imaging however also provides additional benefits that include portrayal of plaque morphology, guidance on stent implantation and sizing and may portend improved clinical outcomes. Looking forward, research in computational fluid dynamics now seeks to integrate both lesion-based physiology and anatomical assessment using intravascular imaging. This review will discuss the rationale and indications for the use of intravascular imaging assessment of intermediate lesions, while highlighting the current limitations and benefits to this approach.

THE MECHANICAL FACTORS INFLUENCING THE ASSESSMENT OF INTERMEDIATE STENOSIS SEVERITY EXPLAINED THROUGH FRACTIONAL FLOW RESERVE

Assessment of intermediate coronary lesions with diameter stenosis of 40% to 70% severity is being a challenge for cardiologist to identify potentially ischemic stenosis for revascularization and nonculprit stenosis which can be deferred from stenting. An invasive coronary angiography and intravascular ultrasound provide anatomic information of stenosis severity whereas an invasive fractional flow reserve index (FFR) provides the functional significance of the stenosis severity. The measurement of functional significance of stenosis severity minimizes the procedural complications such as coronary dissection, in stent restenosis etc. rather than anatomical significance measure. The FFR cutoff value of [Formula: see text]0.8 is used to distinguish ischemic and nonischemic stenosis. The FFR is clinically well validated even though it is influenced by the mechanical factors such as hyperemic flow and guide wire insertion. In recent times, noninvasive coronary computed tomography (CCTA) modality has become popular in the diagnosis of coronary artery disease. The CCTA permits the assessment of cross-sectional parameters such as minimum lumen area and lumen diameter, lesion length and plaque morphology. However, the CCTA provides limited information on the functional significance of stenotic lesions as compared to FFR. The purpose of this review is to discuss the mechanical factors influencing the invasive FFR while assessing the functional significance of intermediate stenosis severity. In addition, the hidden mechanical factors influencing the noninvasive CCTA assessment of stenosis severity will be discussed from the critical information obtained from FFR which could be beneficial for the clinician particularly in the assessment of intermediate stenosis severity.

The clinical impact of routine angiographic follow-up in randomized trials of drug-eluting stents: a critical assessment of "oculostenotic" reintervention in patients with intermediate lesions

OBJECTIVES

The aim of this study was to study the long-term clinical effects of routine angiographic follow-up and related reintervention after drug-eluting stenting.

BACKGROUND

Prior stent trials have shown that protocol-mandated angiographic follow-up increases repeat interventions compared with clinical follow-up alone. The long-term clinical impact of this practice is unknown.

METHODS

Long-term outcomes of patients assigned to routine angiographic follow-up in 3 large-scale TAXUS (Boston Scientific, Natick, Massachusetts) trials were compared with patients assigned to clinical follow-up alone, in a propensity score-adjusted patient-level meta-analysis. Outcomes were also compared in patients with treated versus untreated nonischemic intermediate lesions (quantitative angiographic stenosis between >or=40% and <70%) detected at angiographic follow-up.

RESULTS

Target lesion revascularization (TLR) rates at 5 years were significantly higher in the angiographic compared with clinical follow-up cohort (18.3% vs. 11.1%, p < 0.001). This was due to more frequent treatment of intermediate lesions, but there was no associated reduction in rates of cardiac death or myocardial infarction (8.9% vs. 8.8%, p = 0.93). Of patients with nonischemic intermediate lesions, 17% who were not revascularized at the time of angiographic follow-up had a subsequent TLR, whereas 7% of patients who had TLR at this follow-up angiogram required additional revascularization during long-term follow-up.

CONCLUSIONS

A strategy of routine angiographic follow-up increases oculostenotic revascularization of nonischemic intermediate lesions without affecting subsequent rates of cardiac death or myocardial infarction, and TLR was not required in 83% of those lesions. A conservative approach, in which repeat angiography is limited to patients with recurrent ischemia or progressive symptoms, minimizes repeat revascularization of nonischemic intermediate lesions and optimizes long-term event-free survival after drug-eluting stent implantation.