Abstract 4191: Impact of Proximal Balloon Occlusion on the Measurement of Luminal Size and Fibrous Cap Thickness by Optical Coherence Tomography
Background: Optical coherence tomography (OCT) provides accurate measurement of coronary lumen diameter and fibrous cap thickness in vivo. Because OCT requires blood-free zone for imaging, low pressure (−0.5atm) proximal balloon occlusion (PBO) combined with distal flush (0.5–2ml/sec) from the tip of the catheter or bolus injection (2.5– 4ml/sec) of crystalloid fluid through the guiding catheter without PBO is performed during OCT imaging. The purpose of this study was to investigate the effect of PBO on the assessment of the lumen size and the fibrous cap thickness by OCT in patients.
Methods: We performed OCT with and without PBO in 14 patients. The lumen diameter (LD), the lumen cross sectional area (CSA) and the minimal fibrous cap thickness (FCT) were compared between 40 lesion pairs. Presence of the calcified plaque in each lesion was also evaluated. In 5 patients, intracoronary pressure with and without PBO was compared using the pressure wire.
Results: With PBO, intracoronary pressure was diminished from 75.5±29.5 to 19.8±2.9 mmHg (p<0.001). Maximal and minimal LD were decreased with PBO by −5.5% (p<0.001) and −6.9% (p<0.001), respectively. CSA was also decreased with PBO by −11.5% (p<0.001). FCT was significantly increased from 63±31 to 88±44 micrometer (p<0.007). These differences were prominent in 25 lesions without a large (<2 quadrants) calcified plaque (Maximal LD: −6.5%, p<0.001; Minimal LD: −10.2%, p<0.001; CSA: −15.7%, p<0.001; FCT: +48.8%, p<0.05).
Conclusion: The presence of proximal balloon occlusion influences lumen size and fibrous cap thickness assessed by OCT. The differences are further affected by the plaque morphology.