Validation of a semi-automatic software for optical coherence tomography - analysis in heart transplanted patients.

Optical Coherence Tomography (OCT) is an intravascular imaging modality enabling detailed evaluation of cardiac allograft vasculopathy (CAV) after heart transplantation (HTx). However, its clinical application remains hampered by time-consuming manual quantitative analysis. We aimed to validate a semi-automated quantitative OCT analysis software (Iowa Coronary Wall Analyzer, ICWA-OCT) to improve OCT-analysis in HTx patients. 23 patients underwent OCT evaluation of all three major coronary arteries at 3 months (3M) and 12 months (12M) after HTx. We analyzed OCT recordings using the semiautomatic software and compared results with measurements from a validated manual software. For semi-automated analysis, 31,228 frames from 114 vessels were available. The validation was based on a subset of 4287 matched frames. We applied mixed model statistics to accommodate the multilevel data structure with method as a fixed effect. Lumen (minimum, mean, maximum) and media (mean, maximum) metrics showed no significant differences. Mean and maximum intima area were underestimated by the semi-automated method (ß-methodmean = - 0.289 mm2, p < 0.01; ß-methodmax = - 0.695 mm2, p < 0.01). Bland-Altman analyses showed increasing semi-automatic underestimation of intima measurements with increasing intimal extent. Comparing 3M to 12M progression between methods, mean intimal area showed minor underestimation (ß-methodmean = - 1.03 mm2, p = 0.04). Lumen and media metrics showed excellent agreement between the manual and semi-automated method. Intima metrics and progressions from 3M to 12M were slightly underestimated by the semi-automated OCT software with unknown clinical relevance. The semi-automated software has the future potential to provide robust and time-saving evaluation of CAV progression.

Imaging of Cardiac Transplantation: An Overview.

Heart transplantation (HTx) remains the optimal treatment for selected patients with end-stage advanced heart failure. However, survival is limited early by acute rejection and long term by cardiac allograft vasculopathy (CAV). Even though the diagnosis of rejection is based on histology, cardiac imaging provides a pivotal role for early detection and severity assessment of these hazards. The present review focuses on the use and reliability of different invasive and non-invasive imaging modalities to detect and monitor CAV and rejection after HTx. Coronary angiography remains the corner stone in routine CAV surveillance. However, angiograms are invasive and underestimates the CAV severity especially in the early phase. Intravascular ultrasound and optical coherence tomography are invasive methods for intracoronary imaging that detects early CAV lesions not evident by angiograms. Non-invasive imaging can be divided into myocardial perfusion imaging, anatomical/structural imaging and myocardial functional imaging. The different non-invasive imaging modalities all provide clinical and prognostic information and may have a gatekeeper role for invasive monitoring. Acute rejection and CAV are still significant clinical problems after HTx. No imaging modality provides complete information on graft function, coronary anatomy and myocardial perfusion. However, a combination of invasive and non-invasive modalities at different stages following HTx should be considered for optimal personalized surveillance and risk stratification.