Validation of noninvasive assessment of coronary flow velocity reserve in the right coronary artery. A comparison of transthoracic echocardiographic results with intracoronary Doppler flow wire measurements.

Aims: Assessment of coronary flow velocity reserve (CFR) noninvasively using transthoracic Doppler echocardiography (TDE) is validated for the left anterior descending artery only. We evaluated the feasibility and reproducibility to assess CFR using TDE in the right coronary artery, and compared the results with intracoronary Doppler flow wire (DFW) measurements.

Methods And Results: Introduction of a modified apical 2-chamber view allows visualization of the posterior descending branch of the right coronary artery (RPD). 42 consecutive patients (31 men, mean age 61+/-10) with suspected coronary artery disease scheduled for coronary angiography underwent CFR assessment using TDE in fundamental imaging mode; the results were compared with DFW measurements. CFR could be taken noninvasively in 81% (34/42); in case of right dominant- or balanced coronary circulation type success rate was significantly higher (87%; 33/38) than in case of left dominant coronary circulation (25%; 1/4). Correlation between echocardiographically and intracoronary derived CFR results was significant (r=0.85, P<0.0001), as well as reproducibility (r=0.94, P<0.0001) and interobserver variability (r=0.78, P<0.0001).

Conclusion: Coronary flow reserve assessed in the peripheral RCA by TDE concurs very closely with intracoronary Doppler flow wire CFR results. This new approach allows feasible, accurate and reproducible measurement of CFR in the RCA.