oronary spastic angina (CSA) causes myocardial ischemia at rest by abnormal contraction of epicardial coronary arteries without organic stenosis, which often occurs between midnight and early in the morning. 1 The diagnostic accuracy of noninvasive modalities for CSA, such as the cold pressor test or hyperventilation test, has been low, 2 so angiographic assessment in conjunction with spasm-provocation by intracoronary injection of acetylcholine has been the most standard, albeit an invasive, method of diagnosis. 3 However, it may sometimes lead to a serious adverse outcome. 4 The basal coronary arterial tone is increased in patients with CSA. 5,6 Because coronary flow velocity (CFV) is inversely related to lumen size in the distal myocardial bed, 7 elevated basal arterial tone can be assessed as higher flow velocity in the coronary artery. Transthoracic Doppler echocardiography (TTDE) enables reliable measurement of CFV and its reserve (CFVR) in the human left anterior descending artery. 8 We have previously reported that measuring the change of CFVR following nitroglycerin (NTG) administration is useful for assessing basal coronary arterial tone. 9 Accordingly, we evaluated the usefulness of TTDE for noninvasive diagnosis of CSA by assessing coronary arterial tone in the morning. Methods Study Patients and Study DesignWe studied 50 consecutive patients with chest pain at rest who underwent planned coronary angiography and had no significant stenoses. Two patients were excluded because of suboptimal TTDE measurements. A total of 48 patients (age 40-77 years, mean 59.8±9.1; 28 males, 20 females) were included for further analysis.The Institutional Review Board approved the study, and the patients provided written informed consent. Vasodilators were withdrawn at least 72 h before the study, except sublingual NTG, which was withdrawn at least 2 h before the study. The patients fasted overnight and did not smoke within 2 h prior to the study. All foods or drinks containing flavonoids, catechins or caffeine were withheld during the study. The Doppler examinations were performed prior to the cardiac catheterization in the morning. CFV MeasurementsTTDE was performed with 5-MHz transducer connected to Vivid 7 echocardiographic machine (GE-Vingmed Ultrasound, Horton, Norway), by an experienced investigator. The distal left anterior descending artery was examined using color Doppler mapping with a velocity ranging from -15 to +15 cm/s. After positioning a sample volume where the ultrasonic beam was as parallel to the direction of the distal part of the left anterior descending artery as possible,

Circulation Journal Official Journal of the Japanese Circulation Society http://www. j-circ.or.jp issue Doppler imaging (TDI)-derived strain measurements provide a quantitative assessment of left ventricular regional wall motion without the influence of cardiac tethering and translational artifacts. 1,2Ischemic myocardium is known to present delayed onset and termination of shortening, which may be rarely provided visually. TDI is useful to detect this phenomenon as a prolongation of time to peak strain (TPS) 3 or TPS rate. 4,5 The prolongation of the isovolumic relaxation time has been known to precede systolic dysfunction during acute myocardial ischemia in animal models. 3,6,7 In clinical studies, post-systolic shortening (PSS) was found in ischemic myocardium 8 on TDI during dobutamine stress 2,3,6,7,9-12 or during exercise stress. 5 Adenosine triphosphate (ATP) is a strong vasodilator that dilates the coronary artery by activating A2 receptor after conversion into adenosine. ATP redistributes the coronary blood flow from ischemic region to non-ischemic region, from subendocardial myocardium to epicardial myocardium, resulting in coronary steal and regional myocardial ischemia.The potential advantage of ATP over dipyridamole or dobutamine is its extremely short half-life, less discomfort for the patients and more tolerability and safety as compared to dobutamine stress or exercise stress. 13,14 Previously we have reported that ATP stress provoked a transient delay of contraction assessed on TDI that was correlated with coronary flow reserve in left anterior descending artery (LAD) lesions. 15 The clinical usefulness of ATP stress TDI, however, has not been validated in patients with right coronary artery (RCA) and/or left circumflex artery (LCX) lesions. Moreover, there has been no report on whether ATPinduced contractile delay in ischemic myocardium disappears after coronary revascularization or not.The aims of the present study were therefore to (1) clarify the cut-off of TPSc ratio to detect myocardial ischemia among various regions including in LAD, RCA and LCX diseases; and (2) clarify whether ATP-induced prolongation of TPS disappears immediately after successful percutaneous coronary intervention (PCI) or not. Background: In regional myocardial ischemia, contractile delay develops, which can be assessed by measuring time to peak strain (TPS) on tissue Doppler imaging. The aims of the present study were to clarify the usefulness of TPS measurements during adenosine triphosphate (ATP) stress in assessing myocardial ischemia and to evaluate whether prolongation of TPS disappears immediately after percutaneous coronary intervention (PCI) or not.