Procedural implications of intravascular ultrasound morphologic features of chronic total coronary occlusions

Although the success rates of percutaneous coronary intervention of chronic total occlusions (CTOs) have improved, morphologic features are not well known. We analyzed experience at 4 centers where intravascular ultrasound (IVUS) was performed in 67 native artery CTO lesions (mean CTO duration 6.3 months) just after the lesion was crossed with a guidewire (n = 7) or after dilatation with a 1.5-mm (n = 46) or 2.0-mm (n = 14) balloon. IVUS detected calcium somewhere in the CTO in 96%; however, only 68% had mild calcium. IVUS identified a proximal end of the CTO in all lesions, but a distal end of the CTO in only 50%. An intramural hematoma was observed in 34% of CTOs, suggesting that the guidewire frequently entered the medial space during successful recanalization. CTOs were longer, vessel area was smaller, and total calcium index was greater in lesions with hematomas (p = 0.003, 0.05, and 0.03, respectively). Inadequate reflow after the procedure was observed in 9% and was associated with longer lesions and intralesional calcium. CTO length as measured with angiography was shorter than the length as measured with IVUS (p = 0.02). Calcium was detected on the angiogram in 61% (p = 0.054 vs IVUS). Most typical angiographic findings associated with a low rate of procedural success were not associated with different IVUS morphologies. In conclusion, CTO lesions had multiple small calcium deposits, intramural hematomas were common and were indicative of guidewire penetration into the medial space during the CTO procedure, especially in long calcified lesions in smaller vessels, and inadequate reflow after the procedure was correlated with more complex CTO morphology.