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Summary and ConclusionThe long term consequence of coronary artery disease (CAD) remains a chronic clinical problem, particularly with new therapeutic strategies that reduce the mortality associated with acute coronary syndromes and so more patients suffer from the long term sequel of CAD, the identification of viable myocardium is an important clinical issue among patients who have CAD and LV systolic dysfunction(Mickleborough et al., 1995).The most common variable influencing short and long term outcome in patients with CAD is the status of LV function and so the ability to distinguish reversible from irreversible myocardial injury is of critical importance in the management of patients with both acute and chronic CAD syndromes (Luciani., et al 2001).Revascularization procedures such as Coronary Artery Bypass Grafting (CABG) or Percutaneous Coronary Intervention (PCI) may improve sever regional and global systolic dysfunction, improve function capacity, improve symptoms of heart failure and long term survival compared with medical therapy or cardiac transplantation (Rankin et al., 1999) and so we must identify patients who will gain benefit from revascularization and offer revascularization procedures only to patients who are more likely to achieve an improved quality of life or prolonged survival (Thompson, et al., 1996).An article published in 1978 by Diamond., et al presaged the concept of hibernating myocardium; reports of sometimes dramatic improvement in segmental left ventricular function following coronary bypass surgery, although not universal, leave a clear implication that ischemic non infarcted myocardium can exist in a state of function hibernation. Rahimtoola in an article published in 1985, popularized this concept and later suggested that hibernating myocardium is a state of persistently impaired myocardial and left ventricular function at rest due to reduced coronary blood flow that can be partially or completely restored to normal either improving blood flow or by reducing oxygen demand.Detection of viable myocardium in patients with CAD and left ventricular dysfunction not only identifies those in whom improvement in cardiac function is likely after revascularization but also identifies a group of high risk patients in whom revascularization improves survival (Senior et al ., 1999) .Dysfunctional but viable LV segments do not always recover resting LV function post revascularization, however patients with myocardial viability can have significant improvement in symptoms and prognosis post PCI and this may be due to improvement in contractile reserve (Zaglavara et al., 2000).This study was carried out in cardiology department, faculty of Medicine, Zagazig University; in the period from July 2002 to July 2004. A Fifty three (53) patients ,planned to have elective PCI, were eligible for inclusion in this study three (3) patients did not complete the study ,Two (2) of them up due to failure to cross total occlusion and one (1) patient due to inadequate revascularization. Fifty patients (50) enrolled in the study (40 men, 10 women; mean age ± SD 51.8 ± 10 years).The following was done for every patient:• Complete history taking and thorough clinical examination.• Resting 12-lead ECG.• Routine laboratory tests e.g. Serum creatinine, C.B.C. and bleeding profile.• Chest x-ray.• Diagnostic Coronary Angiography• Resting Echocardiography was done on two separate occasions, the first was done one week before PCI to have a baseline study for wall motion abnormality and the second was done (45 ± 5 days) after PCI. The following data were assessed in each study, Measurement of LV dimensions and LV volumes, LV systolic Function (EF), Regional wall motion• Contractile reserve was assessed in all patients before revascularization by dobutamine stress echocardiography (DSE), Each patient underwent a DSE within 1 week before PCI and to assess the recovery of ventricular function after revascularization, follow-up DSE was done (6 to 8 weeks) after PCI.• Percutaneous Coronary Intervention (PCI) with successful revascularization.Our study showed that;1) Predictive power of DSE in detection of recovery after PCI in patients with systolic dysfunction: In relation to the results of DSE before PCI we calculate the sensitivity, specificity, positive predictive value, negative predictive value and accuracy of DSE for detection of recovery of segmental function for hypokinetic segments, akinetic segments and all the dyssynergic segments as a group.• For hypokinetic segments Sensitivity was 93 %, specificity was 67 %, positive predictive value was 83 %, negative predictive value was 85% and accuracy was 84 %.• For akinetic segments Sensitivity was 81 %, specificity was 78 %, positive predictive value was 70 %, negative predictive value was 87 % and accuracy was 80 %.• For dyssynergic segments (as a group) Sensitivity was 90 %, specificity was 76 %, positive predictive value was 79 %, negative predictive value was 87% and accuracy was 83 %.2) Recovery of function after revascularization in relation to the type of pre-PCI DSE response:A) Biphasic response; sensitivity was 60%, Specificity was 80 %, positive predictive value was 71 %, negative predictive value was 71 % and accuracy was 72 %B) Sustained improvement response; sensitivity was 30%, Specificity was 87%, positive predictive value was 66 %, negative predictive value was 59 % and accuracy was 60 %.3) Comparison between the type of DSE response before and after PCI showed that biphasic response was present in 37 % of cases before PCI and in 11 % post PCI while sustained improvement response was present in 21 % of cases pre PCI and in 46 % of cases post PCI.4) Comparison between the EF during different stages of the study: The mean resting ejection fraction EF (±SD) increased from 39 ±4.6 % in the resting study pre-PCI to 51 ± 5 % at the end of Low dose DSE. Post-PCI, the mean resting ejection fraction EF (±SD) increased to 45 ± 5% in the resting study and to 60± 3 % at the end of Low dose DSE follow up study.Complications:There was no serious complications occurred as a result of PCI.There was no complications as a result of DSE, life threaten arrhythmias, angina, head numbness and dizziness did not occur in any patients.These finding denote that this test is safe in patients with CAD and LV systolic dysfunction.Conclusion:• Resting echocardiography may underestimate the benefits of revascularization in patients with systolic dysfunction and viable myocardium, however post –PCI the contractile reserve in response to inotropic stimulation during DSE increases further and contribute to a significant functional improvement in these patients.• Our results suggest the need for both low and high doses of dobutamine for optimal assessment of myocardial viability in patients with stable CAD and systolic dysfunction• DSE is highly sensitive a predicting recovery of function post- PCI in patients with systolic dysfunction.• Biphasic response during DSE is sensitive and highly specific for detection of improvement post –PCI.
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