Comparison of deformation imaging and velocity imaging for detecting regional inducible ischaemia during dobutamine stress echocardiography.

AIMS: To determine whether Doppler based myocardial tissue velocity imaging (TVI) or strain rate imaging (SRI) is more accurate in detecting stress-induced ischaemia during dobutamine stress echocardiography (DSE). METHODS AND RESULTS: Regional myocardial velocity, displacement, strain rate and strain patterns during DSE were investigated in 44 routine patients with known or suspected coronary artery disease. Simultaneous perfusion scintigraphy defined regional ischaemia. Curves and curved-M-mode patterns were analysed and receiver-operating-characteristics of TVI and SRI parameters were compared by their area under the curve (AUC) in the receiver-operating-characteristics. In non-ischaemic segments, peak systolic velocity and strain rate increased significantly. Unlike SRI, TVI parameters had higher values in basal than in apical segments. In 47 segments of 19 segments DSE-induced ischaemia, which was proven by scintigraphy. In ischaemia, velocity and strain rate increased less. Post-systolic shortening (PSS) was always seen in SRI but not regularly in TVI. Peak systolic velocity and systolic displacement were the best TVI-parameters of stress-induced ischaemia (AUC 0.68 and 0.77, respectively.), in SRI it was the ratio of PSS and maximal segmental deformation (AUC=0.95, p < 0.0001). CONCLUSION: Compared to TVI, SRI parameters showed no major apico-basal gradient and had significantly higher diagnostic accuracy, comparable to conventional reading. SRI thus appears superior to TVI for regional ischaemia detection during DSE and may be preferred to support conventional DSE reading.

Incidence and characteristics of segmental postsystolic longitudinal shortening in normal, acutely ischemic, and scarred myocardium.

OBJECTIVE: Myocardial longitudinal shortening after aortic valve closure (postsystolic shortening [PSS]) is considered a marker of pathology with diagnostic potential. However, PSS can also occur in healthy subjects. We, therefore, investigated the occurrence and characteristics of PSS in control subjects and patients, and how to distinguish normality from disease. METHODS: In 20 young control subjects, 10 older control subjects, 30 patients with acute myocardial infarction (acute ischemia), and 10 patients with postischemic myocardial scar, longitudinal myocardial deformation was measured with Doppler tissue strain rate (SR) imaging. Segmental SR and strain were visually and quantitatively analyzed and compared. RESULTS: In young control subjects, PSS was found in 98 of 313 segments (31%) and showed gaussian distribution (median 1.3%). During ejection time, median peak SR was -1.4 s(-1) and median strain -16.6%. In older control subjects, parameters differed only slightly. In acutely ischemic and scarred myocardium, both systolic strain and SR were significantly reduced or inverted. In disease, PSS occurred significantly more often (78% and 79%, respectively), was significantly higher in magnitude, and its peak occurred later than in young and older control subjects. CONCLUSION: PSS is a normal finding in healthy subjects occurring in approximately one-third of myocardial segments and, thus, is not always a marker of disease. Our data indicate that pathologic PSS can be detected by coexisting reduction in systolic strain and, second, by exceeding a postsystolic strain magnitude cutoff.

Strain-rate imaging during dobutamine stress echocardiography provides objective evidence of inducible ischemia.

BACKGROUND: Interpretation of dobutamine stress echocardiography (DSE) is subjective and strongly dependent on the skills of the reader. Strain-rate imaging (SRI) by tissue Doppler may objectively analyze regional myocardial function. This study investigated SRI markers of stress-induced ischemia and analyzed their applicability in a clinical setting. METHODS AND RESULTS: DSE was performed in 44 patients with known or suspected coronary artery disease. Simultaneous perfusion scintigraphy served as a "gold standard" to define regional ischemia. All patients underwent coronary angiography. Segmental strain and strain rate were analyzed at all stress levels by measuring amplitude and timing of deformation and visual curved M-mode analysis. Results were compared with conventional stress echo reading. In nonischemic segments, peak systolic strain rate increased significantly with dobutamine stress (-1.6+/-0.6 s-1 versus -3.4+/-1.4 s-1, P<0.01), whereas strain during ejection time changed only minimally (-17+/-6% versus -16+/-9%, P<0.05). During DSE, 47 myocardial segments in 19 patients developed scintigraphy-proven ischemia. Strain-rate increase (-1.6+/-0.8 s-1 versus -2.0+/-1.1 s-1, P<0.05) and strain (-16+/-7% versus -10+/-8%, P<0.05) were significantly reduced (both P<0.01 compared with nonischemic). Postsystolic shortening (PSS) was found in all ischemic segments. The ratio of PSS to maximal segmental deformation was the best quantitative parameter to identify stress-induced ischemia. Compared with conventional readings, SRI curved M-mode assessment improved sensitivity/specificity from 81%/82% to 86%/90%. CONCLUSIONS: During DSE, SRI quantitatively and qualitatively differentiates ischemic and nonischemic regional myocardial response to dobutamine stress. The ratio of PSS to maximal strain may be used as an objective marker of ischemia during DSE.