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: Dobutamine as 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 (NTG) can give the same results without these side effects and relatively low cost. Therefore, we evaluated the role of using NTG 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 systolic dysfunction (EF <40%). All the patients had echo findings showing akinetic segments related to the infarcted territory.24 patients underwent viability test using LDDE while 21 patients underwent NTG echo. Coronary angiography (CA) was performed only in patients with positive viability with LDDE or NTG echo intervening in the artery consistent with the results of the non invasive test. Patients who underwent CA based on the results of LDDE and NTG 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 NTG 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 NTG 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 NTG 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 found that WMSI showed a significant improvement in the NTG group compared to the LDDE group confirming myocardial viability in the group that underwent viability test using NTG. 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.