Javlja li se mehanička disperzija s inducibilnom ishemijom tijekom dobutaminske stres ehokardiografije? 2D speckle tracking studija.

AIM: Mechanical dispersion (MD) was recently established as an indicator of greater susceptibility to fatal arrhythmias in patients (pts) after myocardial infarction and suggests the presence of post-systolic shortening (PSS), which was demonstrated in pts with inducible ischemia (II) on dobutamine stress echocardiography (DSE). Furthermore, PSS has also been suggested in patients developing an LV intracavity gradient (ICG) during DSE. Thus, we sought for a potential increase in MD in pts undergoing full dose DSE for II. PATIENTS AND METHODS: DSE was acquired in 30 patients (pts) (17 male, mean age 58±12 years). Procedure included ultrasound acquisition of apical 2, 3 and 4 chamber views during an increase of dobutamine (dbt) up to a full dose of 40 mcg/kg/min or reaching target HR. According to the result, we divided the pts to 3 groups: DSE negative pts, who developed an ICG (Grad+, 10 pts), DSE negative, gradient negative pts (DSE-, 10 pts) and DSE positive, ICG negative pts (DSE+, 10 pts). None of the DSE positive pts developed ICG. Images acquired during baseline and peak dbt dose were analyzed using 2D-speckle tracking, obtaining a 17-segment LV model. Time from peak R wave on ECG to peak strain was measured and MD was calculated as the SD of the time to peak strain between the 17 segments. To compare the groups, we calculated the ratio of MD at peak dose to MD at baseline (MDp/MDb) in each pt, expressing the increase in MD. RESULTS: All 3 groups showed an increase in MD at peak dose, with the greatest increase occurring in the DSE+ group: MDb 38.04 vs. MDp 81.64, p≤0.002 (MDp/ MDb=2.25±1.22). Both DSE negative groups showed similar results-Grad+: MDb 38.94 vs. MDp 55.51, p≤0.001 (MDp/ MDb=1.47±0.41); DSE-: MDb 46.69 vs. MDp 63.86, p≤0.01 (MDp/MDb=1.45±0.51). MDp/MDb of the DSE+ group was significantly greater compared to the Grad+ group (P=0.04), as well as to the DSE- group (P=0.05). CONCLUSION: Pts with a positive DSE demonstrated a greater increase in MD compared to the pts who did not develop II, regardless of the development of an ICG. This suggests that the potential occurrence of PSS with an inducible ICG is less extensive than with II. Data confirm the role of MD in detecting pts at risk, suggesting it may be used as an adjunct in the interpretation of DSE data. [ABSTRACT FROM AUTHOR]