Diagnostic Value of Left Ventricular Dyssynchrony After Exercise and at Rest in the Detection of Multivessel Coronary Artery Disease on Single-Photon Emission Computed Tomography

Abstract

Circulation Journal Official Journal of the Japanese Circulation Society http://www. j-circ.or.jp he development of electrocardiogram-gated single-photon emission computed tomography (SPECT) has enabled the assessment of left ventricular (LV) function after stress and at rest, which has in turn enabled better detection of coronary artery disease (CAD), particularly that of multivessel pathology. 1-4 Recently, a novel technique was developed to evaluate not only myocardial function, but also LV mechanical dyssynchrony using phase analysis on gated SPECT. 5,6 Using this method, several studies have reported the diagnostic and prognostic value of LV mechanical dyssynchrony in patients with heart failure. 7-9 Although LV regional disparities in contractility are known to occur during periods of demand ischemia such as in exercise or dobutamine infusion, 10,11 few studies have analyzed LV mechanical dyssynchrony after stress and at rest to detect high-risk CAD by applying count-based temporal and spatial phase analysis. 12, 13 Considering the diagnostic challenge of multivessel CAD due to balanced ischemia on myocardial SPECT, we retrospectively evaluated whether exercise-induced LV mechanical dyssynchrony as assessed on phase analysis may have enhanced diagnostic value over conventional perfusion analysis in the detection of multivessel CAD. Editorial p 1832Methods Subjects Subjects consisted of 278 consecutive patients (241 men and 37 women; mean age 62±10 years) with suspected or known Background: Although stress-induced left ventricular (LV) wall motion abnormality is a well-known marker for extensive coronary artery disease (CAD), no study has yet analyzed whether phase analysis of exercise-induced LV mechanical dyssynchrony may have enhanced diagnostic value over conventional perfusion analysis in the detection of multivessel CAD.

Diagnostic Performance of a Cadmium-Zinc-Telluride Single-Photon Emission Computed Tomography System With Low-Dose Technetium-99m as Assessed by Fractional Flow Reserve

“…10, 11 Exercise stress using symptomlimited multistep exercise with a bicycle ergometer was performed by 42 patients. 15 Technetium-99 m tetrofosmin or sestamibi (185 MBq) was given intravenously at 85% of ageadjusted predictive maximal heart rate (target heart rate), or when chest pain or ST-segment depression ≥0.1 mV or leg fatigue developed. Exercise was then continued for 1 min at the same previous level.…”

Usefulness of Phase Analysis to Differentiate Ischemic and Non-Ischemic Etiologies of Left Ventricular Systolic Dysfunction in Patients With Heart Failure

“…44, 45 In addition, previous studies that obtained a high degree of intra-observer and inter-observer reproducibility of the indices of LV mechanical dyssynchrony, have demonstrated the feasibility of this method. 23, 40 Finally, the change in LV regional wall motion after ATP stress was not evaluated in the present study. Although previous studies compared post-stress LV regional wall motion change between exercise and ATP stress, post-stress myocardial change was rarely observed after ATP stress.…”

“…39 In contrast to patients with temporal delay due to a wide QRS, LV regional disparities in contractility are regarded as a predominant mechanism for dyssynchrony in CAD patients. 39, 40 When activation occurs, one part of the LV wall, which has normal myocardium under a normal coronary artery, contracts more strongly than the other with myocardial ischemia or fibrosis. This strong part of the LV wall pushes out the weaker part, which contracts in early diastole.…”

“…12,39 Thus, if the extent of ischemic myocardium were greater, the indices of LV mechanical dyssynchrony would also become greater, particularly in patients with extensive CAD, such as those in the current study. 40 In contrast to exercise stress, although ATP usually does not induce actual ischemia, an increased myocardial blood flow, which is induced by pharmacologic vasodilation in a normal vascular territory, results in increased myocardial contraction. 19,43 Therefore, a difference in contractility may occur after ATP loading, particularly in patients with severe LV dysfunction due to multi-vessel CAD or non-ischemic cardiomyopathy.…”

Presence of Postsystolic Shortening Increases the Likelihood of Coronary Artery Disease: A Rest Electrocardiography-Gated Myocardial Perfusion SPECT Study

“…Advances in QGS software have enabled the analysis of the LV regional wall motion (6)(7)(8). Several previous studies have used this method to investigate the diagnostic and prognostic values of LV dyssynchrony in patients with heart failure (9-13) and ischemic heart disease (14)(15)(16)(17). Postsystolic shortening (PSS), defined as delayed myocardial contraction occurring after end-systole, is observed in patients with flow-limiting coronary stenosis and has also been proposed as a marker of myocardial ischemic memory (18)(19)(20)(21)(22)(23)(24)(25)(26).…”