Stress-induced changes in subendocardial tissue texture in hypertrophic cardiomyopathy: An echocardiographic videodensitometric study

Background: Myocardial ischemia changes myocardial acoustic properties, ind ucing increase of integrated backscatter and blunting of cyclic variation o f backscatter. Stress-induced subendocardial underperfusion has been demons trated in patients with hypertrophic cardiomyopathy (HCM). Aim: To evaluate the potential of a videodensitometric approach in assessing transmural ult rasonic tissue changes in HCM during dipyridamole infusion. Methods: Twenty -two patients (13 males, 50 +/- 12 years) with HCM underwent dipyridamole e cho testing (DET). Myocardial gray levels amplitude was calculated off-line on digitized images in the left subendocardial (LV-endo), right subendocar dial (RV-endo) region of the interventricular septum and posterior wall (lo ng axis parasternal view). Results: The thickness of the interventricular s eptum and posterior wall was 1.9 +/- 0.3 and 1.17 +/- 2.1 cm, respectively. In the LV-endo layer, the cyclic variation was blunted during DET (rest = 37 +/- 14 vs. DET 27 +/- 20%, p < 0.02). In the RV-endo layer and posterior wall, no changes occurred. In the LV-endo layer of the septum, blunting of cyclic variation was more pronounced in the 10 patients with than in the 1 2 without ST-segment depression during DET (21.2 +/- 14.7% vs. 43.8 +/- 15. 8, p < 0.01). Conclusions: In HCM patients, DET induced blunting of cyclic variation without the evidence of wall motion abnormalities. This reduction was more pronounced when electrocardiographic signs of ischemia were simul taneously elicited by DET.