DUAL IMAGING OF REGIONAL WALL MOTION AND LV ELASTANCE CALCULATED SIMULTANEOUSLY DURING STRESS ECHOCARDIOGRAPHY: A LARGE SCALE VALIDATION STUDY IN AN INTERNATIONAL MULTICENTER TRIAL

Abstract

The peak stress/rest ratio of LV elastance (systolic arterial pressure/endsystolic volume) is load-independent meaning LV contractile reserve (LVCR). "Weak” heart (blunted LVCR) shows worse outcome than a "strong” heart (preserved LVCR), and prognostic impact of LVCR outperforms stress-EF. We sought to assess feasibility, positivity rate and relative diagnostic value of RWMA+LVCR in prospective, multicenter, international, effectiveness study. We enrolled 1249 patients (age 60.8±10.8 years, 765 males) referred to stress echocardiography (SE) (known or suspected coronary artery disease)-24 laboratories, six countries (Italy, Brazil, Russia, Serbia, Hungary, Bulgaria). Majority of patients (n=1100) underwent exercise stress with semi-supine ergometer (n=1079), upright bicycle (n=14), treadmill (n=7) exercise, 149 patients (11,9%) underwent dobutamine SE. All underwent dual imaging SE (standard evaluation of Wall Motion Score Index (WMS, 17-segment model). each segment from 1=normal to 4=dyskinetic)+simultaneous LVCR assessment with stress/rest ratio of LV force (systolic blood pressure by cuff sphygmomanometer/end-systolic volume from 2D). All readers passed the upstream quality control reading-RWMA. Methods used for LV calculations: Simpson biplane (preferred), single-plane (second choice), Teichholz (when the former two were not of acceptable quality). Previously established abnormal values of LVCR were <2.0 for exercise and dobutamine. Coronary angiographic verification done in 368 patients, 81,8% (n=301) displaying 1+ vessel disease (significant= ≥50% stenosis). LVCR was measured in 1237/1249 patients (feasibility=99%), no additional imaging time, and extra-analysis time of <3 min/patient. Positivity rate=33.8% for RWMA, 63.8%-LVCR, and 68.9% when either of two criteria was considered. WMSI poorly correlated with LVCR (n=1237, r=0.29, p<0.001). “Weak heart” with reduced LVCR was more often found with inducible RWMA, abnormal (≤5%) increase in EF during stress or underlying CAD (Figure). In selected population of 368 patients with coronary angiography, sensitivity=37% (95% CI 31% -42%) for RWMA, 73% (95% CI 66%-77%) for LVCR, 77% (95% CI 71%-81%) for combined criteria, whereas specificity was 80% (95% CI 69%-87%) for RWMA, 32% (95% CI 24%-45%) for LVCR and 32% (95% CI 22%-42%) for combined criteria. During exercise or dobutamine SE, simultaneous dual imaging of RWMA and LVCR is highly feasible, does not add complexity or extra-imaging time to the standard protocol, minimally increases analysis time, increasesing the positivity rate of RWMA alone, with good sensitivity and poor specificity for CAD identification. A “weak heart” with blunted LVCR targets subclinical myocardial disease, which may be independent from physiologically critical epicardial coronary artery stenosis which are the primary determinant of RWMA.