Myocardial mechanical and QTc dispersion for the detection of significant coronary artery disease.

AIMS: 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 was assessed from a 12-lead electrocardiogram (ECG) as the difference between the longest and shortest QTc intervals. 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 = 0.032), and it was correlated to QTc interval duration (r = 0.47; P < 0.001). In contrast to QTc interval duration and dispersion, both parameters of mechanical dispersion were independently associated with CAD (P < 0.001) and had incremental value over traditional risk factors, wall motion abnormalities, and global longitudinal strain (GLS) for the detection of significant CAD. CONCLUSION: The QTc interval and myocardial contraction duration are related to the presence of significant CAD in patients without a history of previous myocardial infarction. Myocardial mechanical dispersion has an incremental value to GLS for identifying patients with significant CAD.

Visual assessment vs. strain imaging for the detection of critical stenosis of the left anterior descending coronary artery in patients without a history of myocardial infarction.

AIMS: We sought to determine the prevalence of overt and subclinical LV dysfunction in patients with critical left anterior descending coronary artery (LAD) stenosis but without a history of myocardial infarction and to compare diagnostic value of routine echocardiographic parameters with myocardial strain analysis for detection of critical LAD stenosis. METHODS AND RESULTS: We retrospectively studied 269 patients with suspected coronary artery disease (CAD)-209 consecutive patients with critical LAD stenosis and 60 consecutive patients with atypical chest pain and without CAD. Conventional visual assessment of LV asynergy in the LAD territory was compared with global, regional, and segmental peak systolic longitudinal strain (PSLS) parameters derived by two-dimensional speckle tracking echocardiography (2D STE). Wall motion abnormalities in the LAD territory were found in 41% of patients with critical LAD stenosis, whereas, depending on the cut-off value, global longitudinal strain (GLS) was impaired in 42-69% of patients. GLS with an area under the receiver operating characteristic curve (AUC) of 0.85 showed better discriminative power for detecting critical LAD stenosis than conventional wall motion score index (AUC 0.73, P < 0.05, for the difference between the AUCs). PSLS values were significantly lower in basal and midventricular segments supplied by critically narrowed LAD, particularly if they also appeared dysfunctional on visual assessment. CONCLUSIONS: Detection of subclinical LV dysfunction by 2D STE might improve identification of patients with critical LAD stenosis, although visually apparent regional LV dysfunction in the LAD territory is not uncommon finding in this subset of patients.