Myocardial Blood Flow and Coronary Flow Reserve During 3 Years Following Bioresorbable Vascular Scaffold Versus Metallic Drug-Eluting Stent Implantation

5-Year Outcomes After Bioresorbable Coronary Scaffolds Implanted With Improved Technique

BACKGROUND

Bioresorbable vascular scaffolds (BVS) were designed to improve late event-free survival compared with metallic drug-eluting stents. However, initial trials demonstrated worse early outcomes with BVS, in part due to suboptimal technique. In the large-scale, blinded ABSORB IV trial, polymeric everolimus-eluting BVS implanted with improved technique demonstrated noninferior 1-year outcomes compared with cobalt chromium everolimus-eluting stents (CoCr-EES).

OBJECTIVES

This study sought to evaluate the long-term outcomes from the ABSORB IV trial.

METHODS

We randomized 2,604 patients at 147 sites with stable or acute coronary syndromes to BVS with improved technique vs CoCr-EES. Patients, clinical assessors, and event adjudicators were blinded to randomization. Five-year follow-up was completed.

RESULTS

Target lesion failure at 5 years occurred in 216 (17.5%) patients assigned to BVS and 180 (14.5%) patients assigned to CoCr-EES (P = 0.03). Device thrombosis within 5 years occurred in 21 (1.7%) BVS and 13 (1.1%) CoCr-EES patients (P = 0.15). Event rates were slightly greater with BVS than CoCr-EES through 3-year follow-up and were similar between 3 and 5 years. Angina, also centrally adjudicated, recurred within 5 years in 659 patients (cumulative rate 53.0%) assigned to BVS and 674 (53.3%) patients assigned to CoCr-EES (P = 0.63).

CONCLUSIONS

In this large-scale, blinded randomized trial, despite the improved implantation technique, the absolute 5-year rate of target lesion failure was 3% greater after BVS compared with CoCr-EES. The risk period for increased events was limited to 3 years, the time point of complete scaffold bioresorption; event rates were similar thereafter. Angina recurrence after intervention was frequent during 5-year follow-up but was comparable with both devices.(Absorb IV Randomized Controlled Trial; NCT02173379).

Endothelial Dysfunction and Coronary Vasoreactivity - A Review of the History, Physiology, Diagnostic Techniques, and Clinical Relevance

The fervency for advancement and evolution in percutaneous coronary intervention has revolutionised the treatment of coronary artery disease. Historically, the focus of the interventional cardiologist was directed at the restoration of luminal patency of the major epicardial coronary arteries, yet whilst this approach is evolving with much greater utilisation of physiological assessment, it often neglects consideration of the role of the coronary microcirculation, which has been shown to clearly influence prognosis. In this review, we explore the narrative of the coronary circulation as more than just a simple conduit for blood but an organ with functional significance. We review organisation and physiology of the coronary circulation, as well as the current methods and techniques used to examine it. We discuss the studies exploring coronary artery endothelial function, appreciating that coronary artery disease occurs on a spectrum of disorder and that percutaneous coronary intervention has a latent effect on the coronary circulation with long-term consequences. It is concluded that greater recognition of the coronary artery endothelium and mechanisms of the coronary circulation should further guide revascularisation strategies.

Evolution of coronary artery calcium and absolute myocardial perfusion after percutaneous revascularization: A 3-year serial hybrid [15O]H2O PET/CT imaging study

BACKGROUND AND AIMS

The value of serial coronary artery calcium (CAC) scores to predict changes in absolute myocardial perfusion and epicardial vasomotor function is poorly documented. This study explored the association between progression of CAC score and changes in absolute myocardial perfusion.

METHODS

Fifty-three patients (26% female) with de novo single-vessel coronary artery disease underwent [¹⁵O]H₂O positron emission tomography/computed tomography at 1 month (baseline), 1 year, and 3 years after complete revascularization with percutaneous coronary intervention (PCI) to assess CAC scores, hyperemic myocardial blood flow (hMBF), coronary flow reserve (CFR) and cold pressor test MBF (CPT-MBF), within the context of the VANISH trial.

RESULTS

Baseline CAC score was 0 in 9%, 0.1-99.9 in 40%, 100-399.9 in 36% and ≥400 in 15% of patients, respectively. Mixed model-analysis allowed for averaging perfusion indices over all time points: hMBF (3.74 ± 0.83; 3.33 ± 0.79; 3.08 ± 0.78 and 2.44 ± 0.74 mL min^-1·g^-1) and CFR (3.82 ± 1.12; 3.17 ± 0.80; 3.19 ± 0.81; 2.63 ± 0.92) were lower among higher baseline CAC groups (p < 0.01; p = 0.03). However, no significant interaction was found between baseline CAC groups and time after PCI for all perfusion indices, denoting that evolution of perfusion indices over time was not significantly different between CAC groups. Furthermore, CAC progression was not correlated with evolution of hMBF (r = 0.08, p = 0.57), CFR (r = 0.09, p = 0.53) or CPT-MBF (r = 0.03, p = 0.82) during 3 years of follow-up.

CONCLUSIONS

Higher baseline CAC was associated with lower hMBF and CFR. However, both baseline CAC and its progression were not associated with evolution of absolute hMBF, CFR and CPT-MBF over time, suggesting that CAC score and progression of CAC are poor indicators of change in absolute myocardial perfusion.

Coronary vasomotor function and myocardial flow with bioresorbable vascular scaffolds or everolimus-eluting metallic stents: a randomised trial

AIMS

The aim of this study was to compare the hyperaemic flow and vasomotor response to endothelium-dependent stimuli between bioresorbable vascular scaffolds (BVS) and metallic everolimus-eluting stents (EES) at 13 months.

METHODS AND RESULTS

Seventy non-diabetic patients aiming to achieve complete revascularisation were randomised 1:1 to BVS or EES implantation. At 13 months, invasive coronary angiography was performed using intracoronary pressure and Doppler ultrasound measurements at rest and maximal hyperaemia. A vasomotor test to endothelium-dependent (acetylcholine) and independent (nitroglycerine) stimuli and optical coherence tomography (OCT) were also performed. Fifty-nine patients (30 BVS and 29 EES) underwent 13-month examination. Doppler ultrasound average peak velocity (49.0±17.5 vs 49.3±18.3 cm/sec; p=0.95), coronary blood flow (97.4±53.5 vs 88.3±46.7 ml/min; p=0.51), coronary flow reserve (2.6±0.9 vs 2.7±0.8; p=0.84) and fractional flow reserve (0.92±0.06 vs 0.94±0.04; p=0.17) were similar between the groups. The vasomotor test showed vasoconstriction response to acetylcholine in 75.6% proximal and 72.2% distal peri-scaffold segments without differences between study devices. BVS had larger in-scaffold vasoconstriction than EES (60.0% vs 27.6%; p=0.01) despite similar neointima response as assessed by OCT.

CONCLUSIONS

BVS and EES had similar microcirculatory response to hyperaemia and predominant vasoconstrictive response in the peri-scaffold segments to endothelium-dependent stimuli. However, BVS exhibited larger vasoconstriction to endothelium-dependent stimuli in the scaffold segment.