Angiography-derived assessment of coronary microcirculatory resistance in patients with chronic total occlusion.

Coronary microvascular dysfunction (CMD) represent a crucial and often underdiagnosed cause of myocardial ischemia and dysfunction. It is closely linked to the prognosis of patients with coronary artery disease. Increased microvascular resistance (whether due to CMD or vascular rarefaction) is more frequent in the setting of coronary chronic total occlusions (CTO). Whether recanalization contributes to the recovery of microvascular function and whether measures of microvascular resistance can potentially be used as prognostic parameter to predict long-term success of CTO recanalization remains unknown. The aim of this study was to investigate CMD in patients with CTO and the effect of successful CTO recanalization. As well, we investigate whether CMD can be identified as a risk factor for restenosis after CTO recanalization. 119 patients underwent successful CTO recanalization at the University Medical Center in Mainz. After a follow-up period of 6 months, invasive control was carried out, in which 79 patients continued to have sufficient revascularization and 40 presented with restenosis. Angiography-based microvascular resistance (Angio-IMR) measurements were performed directly after successful CTO recanalization and at 6 months follow-up offline using a software package (QAngio XA 3D; Medis Medical Imaging Systems). 64% of the patients were male with an average age of 62 ±  9 years. The mean follow-up period was 191 ± 80 days. Median J-CTO Score was 1.8 ± 0.7. The CTO was localized at the RCA in 60%, at the LAD in 20% and at the LCX in 24% of the patients. All included patients had a good result after CTO recanalization confirmed by Quantitative flow ratio (QFR) of 0.94 ± 0.04 directly after PCI. Angio-IMR values immediately after CTO recanalization were pathological (> 25) in 78% of the patients and showed a significant decrease at 6 months follow-up (31.7 ± 7.1 vs. 28.6 ± 5.3¸ p = 0.0024). Post-procedural angio-IMR values did not predict restenosis at 6-month follow-up (31.7 ± 8 vs. 29.8 ± 7.5, p = 0.173). CMD can be detected in a majority of patients after successful CTO PCI. At 6 months follow-up we found significant improved angio-IMR values; CMD was not a predictor of restenosis.