[Assessment of myocardial function at infarct zone after PTCA infarct-related artery--a study with tissue Doppler echocardiography]

Abstract

Angioplasty of an infarct-related artery (IRA) performed several weeks or months after myocardial infarction (MI) may improve myocardial function. It is still unclear though, how soon wall function is restored following the procedure. This study was designed to assess quantitatively changes of regional left ventricular function after PTCA of IRA by means of tissue Doppler echocardiography (TDE). Thirty nine patients (30 male, mean age 53.4 +/- 8.4 yrs) who had MI 13 +/- 6 weeks earlier were qualified for IRA angioplasty on the basis of dobutamine stress echocardiography (DSE) if a viable myocardium was demonstrated. Regional wall function at infarct zone was assessed by TDE one day before PTCA (exam 1), 1-3 days (exam 2) and 28-30 days (exam 3) after successful angioplasty. Myocardial velocities and time--derived TDE intervals were calculated both in systole (systolic peak velocity--S, pre-ejection period--PEP, contraction time--CT), and diastole (E and A velocity waves, E/A ratio, isovolumic relaxation time--IVRT, rapid filling time--RFT, atrial filling time--AFT). All parameters were measured in longitudinal direction (annulus, basal and medial segments) of posterior (20 pts), anterior (17 pts) and lateral (2 pts) walls. S wave velocity increased between exam 1 and 2 (4.9 +/- 1.2 cm/s vs 5.6 +/- 1.3 cm/s, p < 0.02), whereas E wave decreased between examinations. Pre-PTCA E/A ratio was significantly lower than in exam 2 and 3. PEP decreased between exam 1 and 2 (96 +/- 23 ms vs 84 +/- 16 ms, p < 0.01). Significant correlation was found in IVRT and RFT prior and immediately after PTCA (103 +/- 21 ms vs 87 +/- 20 ms, p < 0.001, 151 +/- 39 ms, vs 170 +/- 30 ms p < 0.01 respectively).

Conclusions: Patients after infarction with persisted viable myocardium may benefit from late angioplasty of IRA. In regional wall function assessment TDE seems to be more sensitive technique than visual wall motion analysis alone. TDE parameters demonstrated a rapid initial improvement. Changes of myocardial velocities (S, E) and time--derived TDE intervals (IVRT, PEP, RFT) are sensitive markers of restored myocardial function.