Osvaldo H. Masoli

Effect of endothelial dysfunction on regional perfusion in myocardial territories supplied by normal and diseased vessels in patients with coronary artery disease

BackgroundEndothelium-dependent regulation of coronary tone affects both conduit and resistance coronary arteries. However, little is known about the usefulness of myocardial perfusion imaging in evaluating coronary endothelial function. We evaluated the relation between invasive angiographic measurements of coronary vasomotion in response to intracoronary acetylcholine and the presence of regional perfusion abnormalities assessed by technetium 99m sestamibi imaging.Methods and ResultsWe studied 11 patients (9 men and 2 women) with suspected coronary artery disease (48±8 years, mean±standard deviation). We used quantitative coronary angiography to delineate the vasomotor response to increasing doses of acetylcholine given intracoronary. Regional myocardial perfusion was assessed by planar Tc-99m sestamibi imaging during and after the administration of acetylcholine. In the 11 patients, 23 coronary artery territories were analyzed: 13 were angiographically normal, and 10 showed varying degrees of luminal narrowing. Four (31%) of 13 angiographically normal coronary arteries had a positive vasomotor response to acetylcholine (≥20% reduction in luminal diameter) that was associated with a regional perfusion defect. Acetylcholine induced a positive vasomotor response, which was also associated with a regional perfusion defect in 1 of 3 coronary arteries with stenoses of intermediate severity (50% to 69%). Likewise, acetylcholine induced a positive vasomotor response in 6 of 7 coronary arteries with significant luminal narrowing (≥70%), 5 of which showed a corresponding regional perfusion defect.ConclusionsIn patients with coronary artery disease, noninvasive measurements of regional myocardial perfusion by Tc-99m sestamibi correlate well with invasive measurements of coronary endothelial function. These findings may have implications for monitoring the effects of interventions designed to improve endothelial function and microvascular function in patients with coronary artery disease.

Myocardial perfusion SPECT in the diagnosis of apical hypertrophic cardiomyopathy

BackgroundApical hypertrophy cardiomyopathy (ACM) is a rare condition characterized by asymmetric myocardial hypertrophy of the apex of the left ventricle. When two-dimensional echocardiography is limited by a poor acoustic window, patients are often referred for MRI. Our hypothesis is that a cheaper and more widely available diagnostic modality like myocardial perfusion single photon emission computed tomography (SPECT) may be helpful in the diagnosis of ACM.ObjectiveThe purpose of this prospective study was to define the characteristics of rest and stress SPECT studies in patients with known ACM, and whether SPECT may be helpful in the diagnosis of ACM.MethodsAdult patients with ACM were enrolled in the study. Diagnosis was made with 2-D echo. A rest and exercise or dipyridamole stress SPECT study was performed in all patients with Tc-99m sestamibi.ResultsWe enrolled 20 patients (mean age 60xa0±xa016xa0years), 9 were female, with ACM. SPECT at rest revealed in 15 patients (75%) an increased apical tracer uptake, a spade-like deformity of the left ventricular chamber, and the “Solar Polar” map pattern consistent with ACM. The sensitivity, specificity, positive predictive value, and negative predictive value of SPECT for detecting ACM were 75%, 100%, 100%, and 80%, respectively.ConclusionThree-fourths of adult patients with ACM showed, on myocardial perfusion SPECT, characteristic findings which were not seen in age-matched control subjects, such as a significant increased apical tracer uptake, a spade-like deformity of the left ventricle, and the “Solar Polar” map. Nuclear physicians should be aware of these SPECT findings because many ACM patients may first end up in the nuclear labs due to their markedly abnormal ECG for exclusion of obstructive coronary artery disease.

Amrinone stimulation test: Ability to predict improvement in left ventricular ejection fraction after coronary bypass surgery in patients with poor baseline left ventricular function

OBJECTIVESnThis study sought to determine whether the response to amrinone in patients with severe baseline left ventricular dysfunction can predict improvement in left ventricular ejection fraction after coronary artery bypass graft surgery.nnnBACKGROUNDnPrevious studies have suggested that the inotropic response to dobutamine can identify viable myocardium in the setting of chronic coronary disease and left ventricular dysfunction. However, increased oxygen demand stimulated by dobutamine can lead to superimposition of ischemia on the hibernating state, potentially confounding interpretation of results. Amrinone is an inotropic agent that does not critically augment myocardial oxygen demand and may be useful for identification of hibernating myocardium in the chronically ischemic state.nnnMETHODSnForty-four consecutive patients with coronary artery disease and left ventricular ejection fraction < 40% referred for coronary artery bypass graft surgery underwent amrinone stimulation (1 mg/kg body weight). Left ventricular ejection fraction was determined before amrinone stimulation, 20 min after infusion and 21 days after bypass surgery.nnnRESULTSnBaseline ejection fraction was 28 +/- 7% (mean +/- SD). Ejection fraction increased to 35 +/- 5% after amrinone stimulation (p < 0.0001) and to 33 +/- 6% after bypass surgery (p < 0.0001). Postbypass ejection fraction was significantly correlated with postamrinone ejection fraction (r = 0.65, p < 0.0001). Furthermore, the change in ejection fraction from baseline to after bypass surgery was highly correlated with the change in ejection fraction after amrinone stimulation (r = 0.75, p < 0.0001). Of 13 patients with an increase in ejection fraction > or = 10% after amrinone, all 13 had an increase of at least 8% and 11 (85%) of 13 had an increase > or = 10% after bypass surgery. In contrast, of 31 patients with an increase in ejection fraction < 10% after amrinone, only 2 (6%) had an increase > or = 10% (p < 0.0001) and 28 (90%) of 31 had an increase < 5% after bypass surgery.nnnCONCLUSIONSnAugmentation of myocardial contraction by amrinone in patients with chronic coronary artery disease and severe baseline left ventricular dysfunction predicts improvement in left ventricular ejection fraction after coronary artery bypass graft surgery.

Relationship between endothelial progenitor cells and vascular endothelial growth factor and its variation with exercise

BACKGROUNDnThe aim of our study was to evaluate the effect of programmed physical activity and a single exercise test on the number of CD309+ circulating endothelial progenitor cell (EPC) and their relation to the variation in plasma levels of VEGF in chronic coronary patients.nnnMETHODSn21 patients <75 years with chronic stable coronary artery disease were included. All patients underwent exercise myocardial perfusion SPECT. Then, participants were divided into two groups: one group (11 patients) underwent cardiac rehabilitation program and the other (10 patients) continued with the standard treatment. Blood samples were obtained at baseline, 30 min after exercise ended and at one and three months during follow-up.nnnRESULTSnVEGF values decreased significantly after exercise SPECT test. After one month, there was a significant increase in VEGF levels compared to those measured immediately after exercise. All patients showed a decrease in the values of EPC at 1 and 3-month follow-up. There was an inverse and statistically significant relation between change of EPC and VEGF between the baseline and 1 month.nnnCONCLUSIONSnThe increase of VEGF at 1-month, with respect to baseline values correlated with decreased levels of EPC. This association was independent of the onset of ischemia in the perfusion study.