Use of Coronary Physiology in the Catheterization Laboratory to Guide Treatment in Patients With Coronary Artery Disease

Quantification of the Effect of Pressure Wire Drift on the Diagnostic Performance of Fractional Flow Reserve, Instantaneous Wave-Free Ratio, and Whole-Cycle Pd/Pa

Background—

Small drifts in intracoronary pressure measurements (±2 mm Hg) can affect stenosis categorization using pressure indices. This has not previously been assessed for fractional flow reserve (FFR), instantaneous wave-free ratio (iFR), and whole-cycle distal pressure/proximal pressure (Pd/Pa) indices.

Methods and Results—Four hundred forty-seven

stenoses were assessed with FFR, iFR, and whole-cycle Pd/Pa. Cut point values for significance were predefined as ≤0.8, <0.90, and <0.93, respectively. Pressure wire drift was simulated by offsetting the distal coronary pressure trace by ±2 mm Hg. FFR, iFR, and whole-cycle Pd/Pa indices were recalculated and stenosis misclassification quantified. Median (±median absolute deviation) values for FFR, iFR, and whole-cycle Pd/Pa were 0.81 (±0.11), 0.90 (±0.07), and 0.93 (±0.06), respectively. For the cut point of FFR, iFR, and whole-cycle Pd/Pa, 34.6% (155), 50.1% (224), and 62.2% (278) of values, respectively, lay within ±0.05 U. With ±2 mm Hg pressure wire drift, 21% (94), 25% (110), and 33% (148) of the study population were misclassified with FFR, iFR, and whole-cycle Pd/Pa, respectively. Both FFR and iFR had significantly lower misclassification than whole-cycle Pd/Pa (P<0.001). There was no statistically significant difference between the diagnostic performance of FFR and iFR (P=0.125).

Conclusions—

In a substantial proportion of cases, small amounts of pressure wire drift are enough to cause stenoses to change classification. Whole-cycle Pd/Pa is more vulnerable to such reclassification than FFR and iFR.

Long-term outcome of intravascular ultrasound application in patients with moderate coronary lesions and grey-zone fractional flow reserve

OBJECTIVE

This study aimed to assess the long-term outcome of intravascular ultrasound (IVUS) application in patients with a fractional flow reserve (FFR) of 0.75-0.80.

BACKGROUND

Scientifically evaluating anatomical structures is vital because structure influences both physiological function and decision-making in moderate coronary lesions, especially for those with an FFR of 0.75-0.80.

MATERIALS AND METHODS

Patients (n=128) were divided into three groups based on treatment: the drug control group (n=40), the IVUS-percutaneous coronary intervention (PCI) group (n=40) and the IVUS-drug group (n=48). A PCI was performed when a patient had a minimum lumen area less than 4 mm(2) and a plaque burden of 70% or greater. Major adverse clinical events were defined as cardiac death, nonfatal myocardial infarction, target vessel revascularization, including PCI or coronary artery bypass grafting, and unstable angina, all of which were also evaluated during follow-up.

RESULTS

Kaplan-Meier curves indicated that the incidence of major adverse clinical events did not differ between the IVUS-PCI and IVUS-drug groups (5 vs. 6.3%, P=0.810), but the levels in both of these groups significantly decreased compared with the drug control group (5 vs. 22.5%, P=0.024, and 6.5 vs. 22.5%, P=0.026, respectively).

CONCLUSION

The long-term outcome of the application of IVUS in patients with a grey-zone FFR of 0.75-0.80 was superior to that of patients who were treated only with drugs without IVUS measurement. Patients with a grey-zone FFR should receive an individualized treatment strategy according to their IVUS parameters. Patients with the same FFR values may require different treatment strategies.

Intravascular imaging tools in the cardiac catheterization laboratory: comprehensive assessment of anatomy and physiology

Intravascular imaging modalities have an imperative role in contemporary cardiovascular research. Currently, there are several invasive imaging modalities available in the cardiac catheterization laboratory and new technologies are under development. In the current review, we aimed to provide an update on the research applications of contemporary intravascular imaging tools in the cardiac catheterization laboratory. For the purpose of this review, we separately discuss imaging tools for assessment of epicardial disease (fractional flow reserve and hyperemic stenosis resistance), microvascular function (coronary flow reserve, hyperemic microvascular resistance, and index of microcirculatory resistance), endothelial function, atherosclerotic plaque and vascular remodeling (intravascular ultrasound, optical coherence tomography, angioscopy, and near-infrared spectroscopy), and finally the emerging modalities (palpography and wall shear stress profiling).