193 Ultrafast ultrasound myocardial contrast echocardiography for the assessment of ischaemia: first in-human study

Background Clinical myocardial contrast echocardiography (MCE) utilises commercial microbubbles for myocardial perfusion assessment to detect obstructive coronary artery disease (OCAD). Ultrafast ultrasound or High Frame Rate (HFR) MCE due to its high temporal resolution (>1000frames/sec) can reduce noise and improve perfusion assessment. In the first study in humans with OCAD, we assessed the feasibility of detecting ischaemia with HFR MCE using a research platform. Methods 25 consecutive consenting eligible patients consisting of 20 patients with high pre-test probability (PTP) and 5 with low PTP for OCAD underwent rest and stress perfusion imaging using both conventional and HFR MCE during intravenous infusion of ultrasound contrast agent at rest and following vasodilator stress. All patients with high PTP for OCAD also underwent coronary angiography. Qualitative analysis of the extent and intensity of perfusion defects was performed with both conventional and HFR technique and were correlated with coronary angiography. Results Of the 20 pts with high PTP, 18 pts demonstrated OCAD in all of which inducible perfusion defects were seen with both conventional and HFR MCE. Both techniques correctly detected multivessel OCAD. However, the number of segments with perfusion defects by HFR was greater (114) than with conventional MCE (75) (p <0.001) and in 9 (50%) out of 18 OCAD patients, HFR MCE detected severe perfusion defects compared to mild to moderate defects with conventional MCE (p < 0.001), as shown in figure 1 from a patient with occluded obtuse marginal artery. Of the 3 out of 4 pts with low PTP, both MCE techniques detected no perfusion defects. The 5th patient did not tolerate vasodilator stress. Conclusion In the first study in humans with OCAD, Ultrafast or HFR MCE, despite using a research platform without optimisation and without using data processing algorithm unlike conventional MCE, is as accurate for the detection of OCAD. However, HFR MCE detected greater and more severe ischaemic burden which has prognostic implications. Conflict of Interest None