MyocardialmechanicalandQTcdispersionfor the detection of significant coronary artery disease

Ischaemic but viable myocardium may exhibit prolongation of contraction and QT interval duration, but it is largely unknown whether non-invasive assessment of regional heterogeneities of myocardial deformation and QT interval duration could identify patients with significant coronary artery disease (CAD). Methods and results We retrospectively studied 205 patients with suspected CAD who underwent coronary angiography. QTc dispersion wasassessedfroma12-leadelectrocardiogram(ECG)asthedifferencebetweenthelongestandshortestQTcintervals. Contraction duration was assessed as time from the ECG R-(Q-)wave to peak longitudinal strain in each of 18 left ventricular segments. Mechanical dispersion was defined as either the standard deviation of 18 time intervals (dispersionSD18) or as the difference between the longest and shortest time intervals (dispersiondelta). Longitudinal strain was measured by speckle tracking echocardiography. Mean contraction duration was longer in patients with significant CAD compared with control subjects (428+51 vs. 410+40 ms; P ¼ 0.032), and it was correlated to QTc interval duration (r ¼ 0.47; P , 0.001). In contrast to QTc interval duration and dispersion, both parameters of mechanicaldispersionwereindependentlyassociatedwithCAD(P , 0.001)andhadincrementalvalueovertraditional risk factors, wall motion abnormalities, and global longitudinal strain (GLS) for the detection of significant CAD. Conclusion TheQTcintervalandmyocardialcontractiondurationarerelatedtothepresenceofsignificantCADinpatientswithout a history of previous myocardial infarction. Myocardial mechanical dispersion has an incremental value to GLS for identifying patients with significant CAD.