Aims: Neovascularization is closely associated with plaque progression in non-heart transplantation subjects; on the other hand, cardiac allograft vasculopathy causes unfavourable outcomes. Intravascular ultrasound (IVUS) and optical coherence tomography (OCT) can provide microscopic assessment in vivo. The aim of this study was to investigate the impact of neovascularization on intimal proliferation.
Methods and results: Both IVUS and OCT were attempted in 45 consecutive patients during annual catheterization after heart transplantation. There were 115 vessels [28 vessels were catheterized within 8 weeks of heart transplantation (baseline)]. IVUS analysis assessed vessel, luminal, and intimal (vessel-lumen) volume using Simpson's method. Qualitative parameters including microchannel were assessed by OCT. A microchannel was defined as a no-signal tubuloluminal structure with a sharply delineated border considered to represent neovascularization. Microchannel was observed more often in patient who had their heart transplant more than a year prior to the imaging, compared with shorter periods (39.1 vs. 10.7%, P = 0.023). All microchannels were seen in thickness >0.5 mm, and intimal volume index (mm(3)/mm) correlated with frequency of microchannel (r = 0.54, P = 0.04). The risks for microchannels were donor age [odds ratio (OR) 1.11; 95% confidence interval (CI) 1.03-1.22; P = 0.007], cytomegalovirus infection (OR 16.21; 95% CI 1.79-220.09; P = 0.012), diabetes (OR 9.5; 95% CI 1.21-116.10; P = 0.032), LDL-cholesterol (OR 1.07; 95% CI 1.01-1.13; P = 0.010), and intimal volume (OR 2.47; 95% CI 1.13-6.36; P = 0.023).
Conclusion: OCT-identified microchannels increased sharply within the first year and were correlated with intimal volume and coronary risks. This suggests that neovascularization may play an important role in the progression of cardiac allograft vasculopathy.
Keywords: cardiac allograft vasculopathy; coronary imaging; neovascularization; transplant.
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