Role of Nitroglycerin Echocardiography in Detection of Viable Myocardium in Post Myocardial Infarction Patients in Comparison to the Standard Low Dose Dobutamine Stress Echocardiography.

Abstract

Objectives:Dobutamineas an agent used in stress echocardiography is known to cause some side effects that can be severe and annoying to the patient during the

study.Alternatively,Nitroglycerin (NG) can give the same results without these side effects and relatively low cost.Therefore,we evaluated the role  of using NG echo in assessing viable myocardium in post Myocardial infarction patients  in comparison to low dose dobutamine echocardiography.(LDDE).

Methods:This prospective interventional study was performed on 45 adult patients who developed previous myocardial infarction and LV systolicdysfunction (EF <40%).

All the patients had echo findings showing akinetic segments related to the infracted territory.24 patients underwent viability test using LDDE while 21 patients underwent NG echo.

Coronary angiography (CA) was performed only in patients with positive viability with LDDE or NG echo intervening in the artery consistent with the results of the noninvasive test.Patients who underwent CA based on the results of LDDE and NG echo were followed up 3 months later by a “2D” echocardiographic examination to assess improvement in wall motion in segments showing positive viability.

Results:All the patients underwent a viability test using either LDDE or NG echo and only patients with viable akinetic segments underwent coronary revascularization.2D Echo was followed up 3 months after revascularization in those patients showing viable akinetic territories,concluding that ejection fraction was significantly improved in the follow up echo of the improved cases in the NG group (55.57 ± 5.94),compared to LDDE group (45.00 ± 7.91) and this was statistically significant.

The wall motion score index (WMSI) in the NG group decreased from (2.33 ± 0.31) to (0.97 ± 0.22),while for the LDDE group ,the mean WMSI decreased to (1.91 ± 0.03) instead of (2.76± 0.22) and this was statistically highly significant.From this result,we concluded that WMSI

showed a significant improvement in the NG group compared to the LDDE group confirming myocardial viability in the group that underwent viability test using NG.

Conclusion:Nitroglycerin echocardiography is a safe tool and may provide an interesting diagnostic alternative to dobutamine echo to detect myocardial viability in post-MI patients