Assessment of flow velocity reserve by transthoracic Doppler echocardiography and venous adenosine infusion before and after left anterior descendingcoronary artery stenting

Objective We sought to evaluate whether coronary flow velocity reserve (CFR ) (the ratio between hyperemic and baseline peak flow velocity), as measure d by transthoracic Doppler echocardiography during adenosine infusion, allo ws detection of flow changes in the left anterior descending coronary arter y (LAD) before and after stenting. Background The immediate post-stenting evaluation of CFR by intracoronary D oppler has shown mixed results, due to reactive hyperemia and microvascular stunning. Noninvasive coronary Doppler echocardiography may be a more reli able measure than intracoronary Doppler. Methods Transthoracic Doppler echocardiography during 90-s venous adenosine infusion (140 mug/kg body weight per min) was used to measure CFR of the L AD in 45 patients before and 3.7 +/- 2 days after successful stenting, as w ell as in 25 subjects with an angiographically normal LAD (control group). Results Adequate Doppler spectra were obtained in 96% of the patients. Pre- stent CFR was significantly lower in patients than in control subjects (dia stolic CFR: 1.45 +/- 0.5 vs. 2.72 +/- 0.71, p < 0.01; systolic CFR: 1.61 <p lus/minus> 1.02 vs. 2.41 +/- 0.68, p < 0.01) and increased toward the norma l range after stenting (diastolic CFR: 2.58 <plus/minus> 0.7 vs. 2.72 +/- 0 .75, p = NS; systolic CFR: 2.43 +/- 1.01 vs. 2.41 +/- 0.52, p = NS). Diasto lic CFR was often damped, suggesting coronary steal in patients with greate r than or equal to 90% versus <90% LAD stenosis (0.86 <plus/minus> 0.23 vs. 1.69 +/- 0.43, p < 0.01). Coronary stenting normalized diastolic CFR in th ese two groups (2.45 <plus/minus> 0.77 and 2.64 +/- 0.69, respectively, p = NS), even though impaired diastolic CFR persisted in three of four patient s with greater than or equal to 90% stenosis. Stenosis of the LAD was bette r discriminated by diastolic (F = 49.30) than systolic (F = 12.20) CFR (bot h p < 0.01). Conclusions Coronary flow reserve, as measured by transthoracic Doppler ech ocardiography, is impaired in LAD disease; it may identify patients with <g reater than or equal to>90% stenosis; and it normalizes early after stentin g, even in patients with greater than or equal to 90% stenosis. (J Am Coll Cardiol 2001;38:155-62) (C) 2001 by the American College of Cardiology.