CYCLIC VARIATION IN MYOCARDIAL GRAY-LEVEL AS A MARKER OF VIABILITY INMAN - A VIDEODENSITOMETRIC STUDY

Experimental and human studies have shown that a preserved cyclic (dia stolic-to-systolic) echoreflectivity variation, assessed by radiofrequ ency sampling of backscatter signal with non-commercially available pr ototypes, identifies viability in a myocardial segment with a resting dyssynergy. The objective of this study was to assess whether a videod ensitometric analysis of myocardial gray level variation during cardia c cycle might identify viable but dyssynergic myocardium in a clinical setting. Thirty-four patients with a resting dyssynergy (akinesis in 26, marked hypokinesis in eight) in the septum and/or infero-posterior wall were evaluated by videodensitometry. All echo studies were perfo rmed with commercially available instruments in the long axis paraster nal view, with quantitative analysis of gray levels performed off-line on digitized images. Segmental wall motion was assessed with a 16 seg ment model of the left ventricle, each scored from 1, normal? to 4, dy skinetic. A follow-up echo study was obtained in all patients > 4 week s after successful revascularization (in 22 by angioplasty, in 12 by b ypass surgery). Two groups of segments were identified: 18 viable segm ents (contractile improvement of 1 grade or more in resting function a fter revascularization); 16 necrotic segments (no contractile improvem ent in resting function after revascularization). The % cyclic variati on was higher in viable vs necrotic segments (26 +/- 16 vs 1 +/- 13%, P < 0.01), in spite of similar % systolic thickening (5 +/- 5 vs 4 +/- 6%, P = ns) and end-diastolic thickness (10 +/- 2 vs 10 +/- 2 mm, P = ns). When individual patient analysis was performed, % cyclic variati on was below the 95% confidence limits obtained from normal control re gions (n = 34; % cyclic variation = 38 +/- 14) in two out of 18 viable and in 14 out of 16 necrotic segments. A cut-off of greater than or e qual to 9.4% cyclic variations in a dyssynergic segment yielded 89% se nsitivity and 88% specificity for predicting functional recovery follo wing successful revascularization. In conclusion, viable dyssynergic m yocardial segments show a cyclic gray level variation at rest, which c an be detected by simple videodensitometric analysis, much less techno logically demanding than radiofrequency backscatter evaluation.