Impact of the Type of Anticoagulation Therapy on Long-Term Clinical Outcomes in Patients with Coronary Bifurcation Lesion and Atrial Fibrillation-Insights from the Bulgarian Bifurcation Registry

Background and Objectives: Patients with atrial fibrillation and coronary artery disease represent a group with a greater risk of mortality. To evaluate patients with atrial fibrillation (AF) and a significant coronary bifurcation lesion and compare the clinical outcomes between the patients on anticoagulant treatment with Vitamin K antagonist (VKA) and those on direct anticoagulant (DOAC). Materials and Methods: This is a prospective study of patients with AF and stable coronary artery disease, who had evidence of a significant coronary bifurcation lesion. A log-rank test was used to assess the difference in mortality between patients taking VKA and those on DOAC. The primary endpoint was the incidence of all-cause and cardiovascular death at mid-term. Results: A total of 226 patients with AF and a significant bifurcation lesion were included. The mean age was 70.9 ± 9.2, and 70% were males. Of the patients, 123 (54.7%) were on VKA treatment, and 103 (45.3%) were taking DOAC. For a median follow-up time of 55 (39-96) months, overall mortality was 40%, whereas CV mortality was 31%. Both all-cause (28.2% versus 50.4%, p = 0.020) and CV death (12.7% versus 24.9%, p = 0.032) were significantly lower in patients taking DOAC versus those on VKA. In patients treated with PCI, CV mortality was significantly lower in patients taking DOAC (21.4% versus 40.5%, p = 0.032). VKA therapy was an independent predictor of cardiovascular death (HR 1.88; 95% CI 1.11-3.18; p = 0.01), together with chronic kidney disease (HR 1.81; 95% CI 1.13-2.92; p = 0.01). Conclusions: Treatment with DOAC in patients with atrial fibrillation and coronary bifurcation lesion was associated with significantly lower mortality independently of the treatment approach. VKA was an independent predictor of CV mortality.

Impact of coronary bifurcation morphology on wave propagation

The branching pattern of the coronary vasculature is a key determinant of its function and plays a crucial role in shaping the pressure and velocity wave forms measured for clinical diagnosis. However, although multiple scaling laws have been proposed to characterize the branching pattern, the implications they have on wave propagation remain unassessed to date. To bridge this gap, we have developed a new theoretical framework by combining the mathematical formulation of scaling laws with the wave propagation theory in the pulsatile flow regime. This framework was then validated in multiple species using high-resolution cryomicrotome images of porcine, canine, and human coronary networks. Results demonstrate that the forward well-matchedness (no reflection for pressure/flow waves traveling from the coronary stem toward the microcirculation) is a salient feature in the coronary vasculature, and this result remains robust under many scenarios of the underlying pulse wave speed distribution assumed in the network. This result also implies a significant damping of the backward traveling waves, especially for smaller vessels (radius, <0.3 mm). Furthermore, the theoretical prediction of increasing area ratios (ratio between the area of the mother and daughter vessels) in more symmetric bifurcations found in the distal circulation was confirmed by experimental measurements. No differences were observed by clustering the vessel segments in terms of transmurality (from epicardium to endocardium) or perfusion territories (left anterior descending, left circumflex, and right coronary artery).

A Novel Tram Stent Method in the Treatment of Coronary Bifurcation Lesions - Finite Element Study

A novel stent was designed for the treatment of coronary bifurcation lesion, and it was investigated for its performance by finite element analysis. This study was performed in search of a novel method of treatment of bifurcation lesion with provisional stenting. A bifurcation model was created with the proximal vessel of 3.2 mm diameter, and the distal vessel after the side branch (2.3 mm) was 2.7 mm. A novel stent was designed with connection links that had a profile of a tram. Laser cutting and shape setting of the stent was performed, and thereafter it was crimped and deployed over a balloon. The contact pressure, stresses on the arterial wall, stresses on the stent, the maximal principal log strain of the main artery and the side-branch were studied. The study was performed in Abaqus, Simulia. The stresses on the main branch and the distal branch were minimally increased after deployment of this novel stent. The side branch was preserved, and the stresses on the side branch were lesser; and at the confluence of bifurcation on either side of the side branch origin the von-Mises stress was marginally increased. The stresses and strain at the bifurcation were significantly lesser than the stresses and strain of the currently existing techniques used in the treatment of bifurcation lesions though the study was primarily focused only on the utility of the new technology. There is a potential for a novel Tram-stent method in the treatment of coronary bifurcation lesions.

Recent perspective on coronary artery bifurcation interventions

Coronary bifurcation lesions are frequent in routine practice, accounting for 15-20% of all lesions undergoing percutaneous coronary intervention (PCI). PCI of this subset of lesions is technically challenging and historically has been associated with lower procedural success rates and worse clinical outcomes compared with non-bifurcation lesions. The introduction of drug-eluting stents has dramatically improved the outcomes. The provisional technique of implanting one stent in the main branch remains the default approach in most bifurcation lesions. Selection of the most effective technique for an individual bifurcation is important. The use of two-stent techniques as an intention to treat is an acceptable approach in some bifurcation lesions. However, a large amount of metal is generally left unapposed in the lumen with complex two-stent techniques, which is particularly concerning for the risk of stent thrombosis. New technology and dedicated bifurcation stents may overcome some of the limitations of two-stent techniques and revolutionise the management of bifurcation PCI in the future.

Coronary left main and non-left main bifurcation angles: how are the angles modified by different bifurcation stenting techniques?

BACKGROUND

Investigation of the correlation between bifurcation angles and outcomes is limited with discordant results. The aim of this study is to investigate left main (LM) and non-left main (N-LM) bifurcation angles and their modification after percutaneous coronary intervention (PCI). Measurement of all three angles adds to our understanding of bifurcation anatomy and the resultant effect of different stenting techniques.

METHODS AND RESULTS

All three bifurcation angles were described according to the European Bifurcation Club definition: the A (proximal bifurcation angle), the B (distal bifurcation angle) and the C (main branch angle). Measurements were performed in 75 LM and 140 N-LM bifurcations. In LM bifurcations baseline mean values of C, A, and B were 151 degrees +/- 28 degrees, 131 degrees +/- 32 degrees, and 78 +/- 28 degrees, respectively. In bifurcations with 2 stents the B significantly decreased by a mean of 10 degrees (P = 0.003) and A increased by 10 degrees (P = 0.006). Crush stenting significantly decreased B (A - 14 degrees ; P = 0.020) and increased A (A + 21 degrees; P = 0.005), particularly non-true bifurcations. In N-LM bifurcations mean values for C, A, and B were 156 degrees +/- 19 degrees , 144 degrees +/- 22 degrees, and 60 degrees +/- 20 degrees, respectively. Similar to LM bifurcations, the B became narrower mainly at the expense of the A, which became wider. In both types of bifurcations the greatest variation in A and B was found following 2-stent techniques performed in T-shaped (> or =70 degrees) bifurcations.

CONCLUSIONS

In both LM and N-LM bifurcations we found a significant difference in A and B pre- and post-PCI. This difference was driven by the 2-stent technique and was most evident with a baseline bifurcation angle > or =70 degrees. The Crush technique caused the largest angle variation post-procedure, particularly in non-true LM bifurcations.