ObjectiveWall motion abnormalities during acute ST-segment elevation myocardial infarction (STEMI) and the improvement after recanalization depend on the conditions of the coronary occlusion.MethodsFifty-seven patients with first-ever STEMI due to one-artery occlusion, treated with primary PCI, were evaluated. Area at risk and left ventricular wall motion abnormalities were localized with coronary angiography and echocardiography and then compared in relation to the time elapsed from the onset of symptoms at the time of infarction and at 3 months. Left ventricular diameters and ejection fractions were evaluated in relation to the ischemic time.ResultsThree hundred forty-one affected left ventricular segments were detected with angiography, while echocardiography showed 206 segments with motion abnormality. No correlation was found between the regional wall motion index in the area at risk and the time elapsed from the beginning of symptoms. However, the improvement in wall motion abnormalities at the follow-up was dependent on the ischemic time (r=-0.29, p<0.03). The early subgroup showed significant improvement in left ventricular ejection fraction at follow-up (p=0.03), whereas in the late subgroup, a significant increase in left ventricle diameters was observed.ConclusionOur results first demonstrate in humans that in the early hours from the occlusion of the coronary artery, the extent and severity of the wall motion abnormalities inside the area at risk show large variability without relation to the elapsed time since the onset of symptoms. On the other hand, the results of follow-up echocardiography proved that the wall motion improvement was highly dependent on the ischemic time.
In order to make optimal decisions on the treatment of atherosclerotic coronary heart disease (CHD), appropriate evaluation is necessary, including both the anatomical and physiological assessment of the coronary arteries. According to current guidelines, a fractional flow reserve (FFR)–based clinical decision is recommended, but coronary flow reserve (CFR) measurements and microvascular evaluation should also be considered in special cases for a detailed exploration of the coronary disease state. We aimed to generate an extended physiological evaluation during routine FFR measurement and define a new pathological flow–related prognostic factor. Fluid dynamic equations were applied to calculate CFR on the basis of the three-dimensional (3D) reconstruction of the invasively acquired coronary angiogram and the measured intracoronary pressure data. A new, potentially robust prognostic parameter of a coronary lesion called the “flow separation index” (FSi), which is thought to detect the pathological flow amount through a stenosis was introduced in a vessel-specific flow range. Correlations between FSi and the clinically established physiological indices (CFR and FFR) were determined. The FSi was calculated in 19 vessels of 16 patients, including data from the pre- and post-stent revascularization treatment of 3 patients. There was no significant correlation between the FSi and the CFR (r = −0.23, p = 0.34); however, there was significant negative correlation between the FSi and the FFR (r = −0.66, p = 0.002). An even stronger correlation was found between the FSi and the ratio of the resting pressure ratio and the FFR (r = 0.92, p < 0.0001). The diagnostic power of the FSi for predicting the FFR value of <0.80, as a gold standard prognostic factor, was tested by receiver operating characteristic analysis. FSi > 0.022 proved to be the cutoff value of the prediction of a pathologically low FFR with a 0.856 area under the curve (95% confidence interval: 0.620 to 0.972). The present flow–pressure–velocity display provides a comprehensive summary of patient-specific pathophysiology in CHD. The consequences of epicardial stenoses can be evaluated together with their complex relations to microvascular conditions. Based on these values, clinical decision-making concerning both pharmacological therapy and percutaneous or surgical revascularization may be more precisely guided.
BackgroundThe left internal mammary artery (LIMA) is the choice for grafting of the left anterior descending coronary artery (LAD). One possible mechanism of the rare graft failure involve the presence of competitive flow.Method105 patients who had undergone coronary bypass grafting between 1998 and 2000 were included in this observational study. The recatheterizations were performed 28 months after the operations. The rate of patency the LIMA grafts was determined, and the cases with graft failure were analyzed.ResultsThe LIMA graft was patent in 99 patients (94%). Six patients (6%) exhibited diffuse involution of the graft (string sign). The string sign was always associated with competitive flow as the basis of the LIMA graft involution. In one case quantitative re-evaluation of the preoperative coronary angiography revealed merely less than 50% diameter stenosis on the LAD with a nonligated side-branch of the LIMA. At recatheterization in two patients the pressure wire measurements demonstrated only a non-significant decrease of the fractional flow reserve (0.83 and 0.89), despite the 53% and 57% diameter stenosis in the angiogram. Another patient displayeda significant regression of the LAD lesion between the pre- and postoperative coronary angiography (from 76% to 44%) as the cause of the development of the competitive flow. In one instance, a radial artery graft on the LAD during a redo bypass operation resulted in competitive flow in the radial graft due to the greater diameter than that of the LIMA. In a further patient, competitive flow developed from a short sequential part of the LIMA graft between the nonsignificantly stenosed diagonal branch and the LAD, with involution of the main part of the graft to the diagonal branch.ConclusionsThe most common cause of the development of the string sign of a LIMA graft due to competitive flow is overassessment of the lesion of the LAD. Regression of a previous lesion or some other neighboring graft can also cause the phenomenon.
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