Thallium-201 Myocardial Perfusion Scintigraphy Research Articles

O24-1 - Adenosine Thallium-201 Myocardial Perfusion Scintigraphy in Acute Congestive Heart Failure with Preserved Left Ventricular Ejection Fraction

O24-1 - Adenosine Thallium-201 Myocardial Perfusion Scintigraphy in Acute Congestive Heart Failure with Preserved Left Ventricular Ejection Fraction

Validity of automatic function imaging to measure peak systolic strain for detection of myocardial viability as compared with Thalium MPI

Thallium201 myocardial perfusion scintigraphy (MPI) is the most common modality used myocardial viability (MV), automatic function imaging (AFI) to measure peak systolic strain is relatively recent Echocardiographic modality with questionable validity for detection of viability. To evaluated the validity of peak systolic strain for detection of MV as compared with Thallium MPI. Methods: 50 patients with myocardial infarction will be included in our prospective study. Thallium MPI to be used as reference for MV (Rest-4 h and if necessary 24 h protocol). The automatically generated Bulls eye image will be used for quantitative segmental analysis and to be compared with Echocardiographic AFI for peak systolic strain with the 17 segments model of analysis (GE system). The results will be compared as segment by segment as well as regional (as per coronary territory). We present the result of first 10 case series (including analysis of 170 segments). There is over all concordance between the automated count at image of peak systolic strain and the percent of radiotracer uptake at Thallium 201 bulls eye images in both infracted and non infracted segments. The cut value of AFI for viability requires larger sample analysis. There is observed false negative results at segments with very low peak systolic strain as low as-2 that showed mild perfusion defect at rest and complete reuptake at redistribution image. Peak systolic strain is useful modality for assessment of viability, its sensitivity might be limited with false negative results compared with Thallium 201 scintigraphy.

Repeated sauna therapy improves myocardial perfusion in patients with chronically occluded coronary artery-related ischemia

BackgroundRepeated low-temperature sauna (Waon) therapy relieves ischemic symptoms in patients with peripheral arterial disease. We investigated whether Waon therapy could improve myocardial perfusion in patients with ischemia related to chronic total occlusion (CTO) of coronary arteries. MethodsTwenty-four patients who had ischemia in the CTO-related area were examined. The severity of ischemia was quantified by thallium-201 myocardial perfusion scintigraphy with adenosine. The Waon group (n=16) was treated daily for three weeks with a 60°C far infrared-ray dry sauna bath for 15min and then kept in a bed covered with blankets for 30min. The control group (n=8) underwent myocardial perfusion scintigraphy twice with a three-week interval. ResultsIn the control group, neither summed stress score (SSS) nor summed difference score (SDS) of myocardial scintigraphy changed. However, Waon therapy improved both SSS (16±7 to 9±6, p<0.01) and SDS (7±4 to 3±2, p<0.01), and the improvement was greater in patients with higher SSS and SDS scores at the baseline. Waon therapy extended treadmill exercise time (430±185 to 511±192s, p<0.01) and improved flow-mediated dilation of the brachial artery (4.1±1.3 to 5.9±1.8%, p<0.05), but tended to decrease the number of circulating CD34-positive bone marrow-derived cells. ConclusionsWaon therapy improves CTO-related myocardial ischemia in association with improvement of vascular endothelial function. This therapy could be a complementary and alternative tool in patients with severe coronary lesions not suitable for coronary intervention.

Effects of exercise training started within 2 weeks after acute myocardial infarction on myocardial perfusion and left ventricular function: a gated SPECT imaging study

Several studies suggested that exercise training might improve myocardial perfusion by inducing coronary vascular adaptations or enhancing collateralization. However, these findings were obtained in patients with chronic coronary artery disease using thallium-201 myocardial perfusion scintigraphy. We evaluated whether a long-term exercise-based cardiac rehabilitation (CR) started early (9 ± 3 days) after ST elevation acute myocardial infarction (STEMI) improves myocardial perfusion and left ventricular (LV) function, evaluated by gated single-photon emission computed tomography (SPECT) imaging. Randomized controlled study. Fifty patients with recent STEMI were randomized into two groups: 24 enrolled in a 6-month exercise-based CR programme (group T) and 26 discharged with generic instructions for maintaining physical activity and correct lifestyle (group C). All patients underwent cardiopulmonary exercise test and gated SPECT within 3 weeks after STEMI and at 6-month follow up. At follow up, group T showed a significant reduction of stress-induced ischaemia (p < 0.01) and an improvement in resting and post-stress wall motion (both p < 0.005) and resting (p < 0.05) and post-stress wall thickness (p < 0.005) score indexes. At follow up, group T showed an improvement in peak oxygen consumption (p < 0.0001), O(2) pulse (p < 0.05), and in the slope of increase in ventilation over carbon dioxide output (p < 0.001). No changes in myocardial perfusion parameters, LV function, and cardiopulmonary indexes were observed in group C at follow up. Six months of exercise training early after STEMI reduces stress-induced ischaemia and improves LV wall motion and thickness. Exercise-induced changes in myocardial perfusion and function were associated with the absence of unfavourable LV remodelling and with the improvement of cardiovascular functional capacity.

Non-invasive Evaluation of Internal Thoracic Artery Anastomosed to the Left Anterior Descending Artery with 320-Detector Row Computed Tomography and Adenosine Thallium-201 Myocardial Perfusion Scintigraphy

We evaluated the relationship between internal thoracic artery (ITA) stenosis anastomosed to the left anterior descending artery (LAD) and the degree of LAD stenosis using 320-detector row computed tomography (320-ADCT) and adenosine thallium-201 myocardial perfusion scintigraphy (Tl-201-MPS). We included 101 patients who underwent coronary artery bypass grafting (CABG) using ITA grafts; 320-ADCT and adenosine Tl-201-MPS were performed 2-3 months after CABG. Clinical parameters, degree of LAD stenosis, and regional myocardial ischemia of the LAD territory were compared between patients without ITA stenosis (Group A) and with ITA stenosis (Group B). Thirty patients (30%) had ≤75% LAD stenosis, and 9 patients (30%) showed significant ITA stenosis. Regional ischemia was noted in 23 patients (23%). There were no differences in clinical parameters between the 2 groups. Twenty-two patients (24%) in Group A and 8 patients (89%) in Group B had ≤75% LAD stenosis (P <0.002). No Group B patients had regional myocardial ischemia of the LAD territory. We concluded that ≤75% LAD stenosis significantly influences ITA stenosis, without associated regional myocardial ischemia of the LAD territory. Non-invasive 320-ADCT and adenosine Tl-201-MPS for ITA evaluation may be useful for long-term follow-up of patients after CABG.

Valor pronóstico de la gammagrafía de perfusión miocárdica con 201Tl normal en el postinfarto agudo de miocardio

Objective The purpose of this work has been to determine the prognostic value of normal thallium-201 myocardial perfusion scintigraphy (MPS) in patients who had suffered myocardial infarction in the three months prior to the examination. Material and methods A stress test followed by 201Tl Gated SPECT was performed. A follow-up was made of 63 patients with normal perfusion scintigraphy. According to the MPS results, the patients were divided into 2 groups. Group I (n = 63; 57% males, age 65 ± 12), patients with normal MPS, and group II (n = 60; 81% males, age 64 ± 10), patients with abnormal MPS. The appearance of a new infarction or cardiac death occurring during this period (63 ± 3 months) was analyzed. The appearance of events was related with the cardiovascular risk factors, perfusion study and ventricular function. Results Five events occurred in group I in 4 patients: 3 new infarctions and 2 cardiac deaths. In group II, there were 18 events in 14 patients: 8 new infarctions and 10 cardiac deaths (p < 0,0001). The events were related with age, time from MPS, diabetes, size of perfusion defect and post stress ventricular ejection fraction. Mean survival en group I was 108 months (103–112) and in group II 97 (88–107) (p = 0,01). Conclusion Patients with normal MPS had fewer major events than patients with abnormal MPS. The size of MPS has been related with the appearance of events. A depressed post-stress left ventricular ejection fraction has a poor prognosis.

Investigation of the mechanism of reverse redistribution in thallium-201 myocardial perfusion scintigraphy in patients with suspicion for coronary artery spasm

BackgroundReverse redistribution (RR) is one of the features on myocardial perfusion scintigraphy (MPS) in patients with coronary artery spasm (CAS). This study was aimed to explore the mechanism of RR in patients with suspicion for CAS. Methods and ResultsThirty patients with RR and suspicion for CAS but without coronary artery stenosis (RR group) and 32 control patients without RR (control group) underwent coronary angiography before and after a dipyridamole administration. Coronary blood flow velocity and myocardial perfusion, as determined by corrected thrombolysis in myocardial infarction (TIMI) frame count (CTFC) and TIMI myocardial perfusion grade (TMPG), were measured. Coronary angiography showed significantly slower blood flow velocity [CTFC (37 ± 6) frame vs (29 ± 7) frame, P < .01] and lower myocardial perfusion [TMPG (2.08 ± 0.38) grade vs (2.55 ± 0.33) grade, P < .05] in RR-related arteries than in RR-unrelated arteries in the RR group. But, there was no significant difference among different coronary artery branches in the control group. After the injection of dipyridamole, CTFC decreased and TMPG increased in the RR group. The decline in CTFC and the increase in TMPG in RR-related arteries were more significant than those in RR-unrelated ones (28% vs 14% and 45% vs 16%, respectively; both P < .01). The endothelin-1/nitric oxide (NO) ratio was significantly higher in the RR group than in the control group before the injection of dipyridamole (2.79 ± 0.37 vs 1.70 ± 0.19, P < .01). After the injection of dipyridamole, the ratio went down in both groups, but the decline was statistically significant in the RR group (2.42 ± 0.33, P < .05) but not in the control group (1.42 ± 0.19, P < .05). Pearson correlation analysis showed that there was a positive correlation between summed rest scores on MPS and the endothelin-1/NO ratio (r = 0.853, P = .000) as well as CTFC (r = 0.808, P = .000) before the injection of dipyridamole in the RR group. ConclusionPatients with suspicion for CAS may exhibit a mild spasm of RR-related arteries and corresponding microvasculature and a significant imbalance of coronary blood flow velocity and myocardial perfusion at rest between RR-related and RR-unrelated areas. This is overcome by stress-induced hyperemic flow increases and which may account for RR on MPS.

The role of metamizol induction for the detection of perfusion reversibility on thallium-201 myocardial perfusion scintigraphy

Metamizol, probably with its vascular smooth muscle relaxant effect, enhances rest myocardial perfusion with the use of technetium-99m-methoxyisobutylisonitrile. We aimed to investigate whether metamizol induction is also able to increase the detectability of the ischemic/jeopardized myocardium during thallium-201 myocardial perfusion scintigraphy (MPS). Twenty patients who had partially reversible/irreversible perfusion defects on their routine stress-redistribution-reinjection thallium-201 MPS were enrolled and metamizol-induced thallium-201 MPS (111 MBq thallium-201 was injected 45 min after 1 g oral metamizol) was acquired (10 min, 1 and 3 h later). Routine MPS and metamizol-induced MPS images were interpreted on the model of 17 segments using a visual uptake score (VUS; 0=normal, 1=mild, 2=moderate, 3=significant decreases, 4=no uptake). Thallium-201 uptake ratios (mean counts in the region of the perfusion defect/mean counts in the region of the normal-perfused wall) were calculated for each MPS. Blood pressure was monitored at 15-min intervals. MPS were compared with coronary angiography results. Visual uptake score and thallium-201 uptake ratio results indicated that in the first and third hour metamizol-induced thallium-201 uptake was significantly higher (P<0.001) than the redistribution/reinjection studies in 26 ischemic myocardial walls. Fourteen myocardial walls showed no thallium-201 uptake on either MPS and were considered as myocardial infarction. Statistically significant but asymptomatic decreases in blood pressure were observed. Coronary angiography results were in concordance with metamizol-induced MPS. Metamizol increases the detectability of ischemic/viable myocardium during MPS with thallium-201 and could be used with MPS.

Prognostic value of normal myocardial perfusion scintigraphy with 201Tl in post-acute myocardial infarction

Objective The purpose of this work has been to determine the prognostic value of normal thallium-201 myocardial perfusion scintigraphy (MPS) in patients who had suffered myocardial infarction in the three months prior to the examination. Material and methods A stress test followed by 201Tl Gated SPECT was performed. A follow-up was made of 63 patients with normal perfusion scintigraphy. According to the MPS results, the patients were divided into 2 groups. Group I (n = 63; 57% males, age 65 ± 12), patients with normal MPS, and group II (n = 60; 81% males, age 64±10), patients with abnormal MPS. The appearance of a new infarction or cardiac death occurring during this period (63±3 months) was analyzed. The appearance of events was related with the cardiovascular risk factors, perfusion study and ventricular function. Results Five events occurred in group I in 4 patients: 3 new infarctions and 2 cardiac deaths. In group II, there were 18 events in 14 patients: 8 new infarctions and 10 cardiac deaths (p<0.0001). The events were related with age, time from MPS, diabetes, size of perfusion defect and post stress ventricular ejection fraction. Mean survival en group I was 108 months (103-112) and in group II 97 (88-107) (p=0.01). Conclusion Patients with normal MPS had fewer major events than patients with abnormal MPS. The size of MPS has been related with the appearance of events. A depressed post-stress left ventricular ejection fraction has a poor prognosis.

Abstract 4175: Quantitative Assessment of Myocardial Blood Flow Using Adenosine Triphosphate Stress Multidetector-row Computed Tomography in Coronary Artery Disease

Introduction: The purpose of this study was to test the hypothesis that cardiac multidetector-row computed tomography (MDCT) technology can assess myocardial perfusion quantitatively using adenosine triphosphate (ATP) load technique. Methods: Ten patients (median age 71 (range 65–79) years) who were scheduled for surgical revascularization, underwent cardiac electrocardiography-gated MDCT using ATP-load technique. The patients with unstable angina and myocardial infraction were excluded. Myocardial infarction was detected by late gadolinium enhancement MRI which was assessed before MDCT. Myocardial blood flow (MBF) was estimated from the slope of the linear regression equation with Patlak plots analysis. MBF results were compared to the presence of stenoses more than 75% on coronary angiography (CAG) and moderate to severe myocardium ischemia on stress thallium-201 myocardial perfusion scintigraphy (MPS). Results: The overall mean MBF was 1.64±0.61 ml/g/min. Mean MBF in territories with stenosis on CAG was 0.81±0.49 ml/g/min, while mean MBF in territories without stenosis was 1.83±0.64 ml/g/min (p&lt;0.01). Mean MBF in territories with moderate to severe ischemia on MPS was 0.76±0.49 ml/g/min, while mean MBF in territories without ischemia was 2.15±0.66ml/g/min (p&lt;0.01). When the cut off value of MBF was set at 1.5 ml/g/min, there was good correlation between MBF vs CAG, and MBF and MPS. MBF vs CAG: sensitivity=71.4%, specificity=82.6%; MBF vs MPS: sensitivity=85.7%, specificity=87.0%. Conclusions: This study proposed the possibility of MDCT to quantify myocardial blood flow using ATP in coronary artery disease. Our data suggested that the ATP stress MDCT has an advantage in the assessment of CAD to evaluate both coronary artery stenoses and myocardial perfusion information in one modality.

Automated assessment of myocardial SPECT perfusion scintigraphy: A comparison of different approaches of case-based reasoning

This study compared the diagnostic accuracy of different approaches of case-based reasoning (CBR) for the assessment of coronary artery disease (CAD) using thallium-201 myocardial perfusion scintigraphy in comparison with coronary angiography. For each scintigraphic image set, regional myocardial tracer uptake was obtained by polar map analysis. CBR algorithms based on a similarity measure were employed to identify similar scintigraphic images within the case library, where each case contained the scintigraphic data together with results of coronary angiography. The angiographic data of retrieved cases were then used to determine whether significant CAD was present in one of the major coronary arteries. Three different approaches of CBR were compared: (1) case retrieval based on a global comparison of polar map data (GLOB), (2) case retrieval based on a territorial comparison of polar map data (TER), and (3) case retrieval based on a comparison of a given case with eight sub-libraries classified according to the involvement of the three major coronary vessels using a group similarity measure (GROUP). Two matching algorithms the best-match approach and an adapted retrieving approach were combined with all three case retrieval methods and their influence on the diagnostic accuracy were investigated. For overall detection of significant CAD, the best-match approach of both TER and GROUP retrieval methods showed a higher diagnostic accuracy than the GLOB retrieval method (75% and 77% versus 70%, respectively). ROC analysis for the adapted retrieving approach showed a similar diagnostic accuracy for all three methods with an area under the curve of 0.79, 0.8, and 0.8 for GLOB, TER, and GROUP, respectively. The observed improvement in the diagnostic accuracy by the new approaches may lead to further improvements of CBR systems, which have the potential to offer valuable decision support for human readers, especially for less experienced investigators.

Characterization of hibernating myocardium with NOGA electroanatomic endocardial mapping

Because the terms "hibernation" and "viability" are not interchangeable, the recognition of hibernating myocardium within viable segments remained elusive for NOGA electroanatomic endocardial mapping. The aim of the present study was to determine the characteristics of hibernating myocardium in NOGA mapping. Baseline and follow-up endocardial mapping, thallium-201 myocardial perfusion scintigraphy at rest, and contrast ventriculography were performed in 28 patients who had proved viable myocardium before and 7.3 +/- 2.5 months after percutaneous coronary intervention. Significantly improved regional wall motion in the revascularized territory (region of interest) was confirmed in 9 patients (group 1) at follow-up (from -2.11 +/- 0.87 to -1.48 +/- 0.43 SD/chord, p <0.05), whereas no change in regional wall motion was observed in 19 patients (group 2; from -2.56 +/- 0.88 to -2.79 +/- 0.91 SD/chord). Average normalized thallium uptake at rest increased significantly in groups 1 and 2 after revascularization. A trend toward increased unipolar voltages in the region of interest was observed in group 1 at follow-up (from 10.6 +/- 3.5 to 11.7 +/- 4.0 mV, p = 0.073), whereas no change was observed in group 2 (from 8.7 +/- 4.4 to 8.9 +/- 3.8 mV). A significant increase in local linear shortening was measured only in group 1 (from 7.5 +/- 5.2% to 10.3 +/- 3.9%, p <0.05). Hibernating myocardial segments exhibited significantly higher unipolar voltages and late thallium uptake at rest at baseline. Receiver-operator characteristic analysis showed a mean unipolar voltage of 9.0 mV (predictive accuracy 0.708, common sensitivity and specificity 72%) in the region of interest for prediction of functional recovery. In conclusion, for characterizing the hibernating myocardium within viable segments, NOGA endocardial mapping offers on-line guidance for percutaneous coronary and noncoronary myocardial revascularization.

The influence of post-exercise cardiac changes on thallium-gated myocardial perfusion scintigraphy findings in normal subjects*

During recovery after exercise, the heart rate and blood pressure return to a resting state more rapidly than the end-systolic left ventricular dimensions and fractional shortening. The aim of this study was to assess how exercise-related cardiac changes affect the interpretation of myocardial perfusion images in normal subjects. Systolic cardiac parameters on gated stress and rest images were evaluated in healthy young and elderly subjects. Twenty-six healthy young and 20 healthy elderly subjects participated in the study. An injection of 111-130 MBq of thallium-201 (201Tl) was given at peak exercise. Rest images were acquired 2.5 h after stress acquisition, 15 min after a second injection of 18.5-37 MBq of 201Tl. Data were analysed using automatic-processing software for quantitative gated single photon emission computed tomography (SPECT) (QGS). The parameters derived from QGS were the end-systolic volume (ESV), end-diastolic volume (EDV), left ventricular ejection fraction (LVEF), end-systolic surface area (ESSA) and end-diastolic surface area (EDSA). The difference between wall thickening in the basal and apical segments (Delta WT) was also calculated. Perfusion images were visually assessed for differences in cardiac size, evidence of reversible hypoperfusion and hot spots. In the young group, LVEF was approximately 6% higher at stress than at rest. EDV, ESV, ESSA and EDSA were all significantly lower, and Delta WT was significantly higher, at stress than at rest. In the elderly group, the mean LVEF at stress was slightly higher than the finding at rest (P<0.05). Visual evaluation of perfusion images revealed mild reversible stress hypoperfusion in the inferoseptal region in eight young male subjects. In healthy young subjects, post-exercise cardiac changes affect systolic functions detected on gated thallium myocardial perfusion scintigraphy, resulting in a smaller heart size during stress. This finding, accompanied by a significant difference in apex to base counts during stress, may cause basal portions of the heart to appear ischaemic. The absence of these findings in the elderly suggests a decrease in contractility with age.

Myocardial Perfusion Imaging Using Adenosine Triphosphate Stress Multi-Slice Spiral Computed Tomography Alternative to Stress Myocardial Perfusion Scintigraphy

The present study was designed to: (i) detect myocardial ischemia in contrast enhanced multi-slice spiral computed tomography (CE-MSCT) using adenosine triphosphate (ATP) pharmacological stress test; and (ii) evaluate the potential of ATP stress CE-MSCT in a clinical setting. Twelve patients underwent ATP stress CE-MSCT and stress thallium-201 myocardial perfusion scintigraphy (MPS) and 9 of the patients received conventional coronary angiography (CAG). Dual CE-MSCT scans were performed for stress and rest images, with and without intravenous infusion of ATP (0.16 mg.kg-1.min-1) at intervals of 20 min. Myocardial perfusion and coronary artery were visually evaluated using MSCT and compared the results obtained from MPS and CAG. Of 36 territories, stress images of CE-MSCT described 26 hypo-perfusion areas and MPS described 22 redistributions. The agreement between MSCT and MPS was 83% (30/36, p<0.05). In 141 coronary artery segments of 9 patients undergoing CAG, rest images of CE-MSCT, which had significantly higher assessability than stress images (89% vs 48%, p<0.05), described 76% (13/17) of culprit coronary stenoses. Although CT-angiography should be currently assessed using rest images, ATP stress CE-MSCT can describe both ATP-induced myocardial ischemia and coronary artery stenoses in patients with coronary artery disease.

Myocardial perfusion scintigraphy (SPECT) in autologous intracoronary bone marrow cell transplantation

Background: Experimental data suggest that Bone Marrow Derived Stem Cells (BMSCs) may contribute to the healing of myocardial infarction. Therefore, we analyzed the results of 6 patients undergoing Thallium201 myocardial perfusion scintigraphy (SPECT) pre and post- cell transplantation. Methods and Results: 6 patients with chronic heart failure, mean LVEF 29±5%, with history of anterior myocardial infraction, were transplanted with autologous BMSCs via a balloon catheter placed into the infarct-related (LAD) artery. The amount of BMSCs were 15.6 ± 8.5 × 10 6. We studied the patients a few days pre- and 3 months post transplantation, using Thallium-201 myocardial perfusion scintigraphy. We compared the two studies for each patient and calculated the counts from short axis images. Images were assessed by quantitative measures of the activity in the area at risk compared to normal segments for both studies, which were expressed as the ratio postopoerative activity/preoperarive activity. Two Regions of interest (ROI) were selected for each image. The first for the normal and the second for abnormal segment of myocardium. The ratio, r, of counts per pixel of normal ROI to counts per pixel of abnormal ROI was calculated. The average value of r was 2.66±0.6 and 2.33±0.7, p value of 0.039, for pre and post transplantation studies correspondingly. Conclusion: We observe that the r ratio decreases significantly after BMSCs transplantation. This fact of this improvement in counts suggests that this ratio can be used as a critirio for BMSCs which might be associated with myocardial regeneration and revascularization, therefore controlled studies are needed to clarify the role of cell transplantation in myocardial regeneration.

The effect of myocardial surgical revascularization on left ventricular late potentials.

The presence of ventricular late potentials (LP) is an important indicator for the development of ventricular tachyarrhythmias due to ischemic heart disease. The effect of myocardial revascularization on LP has remained controversial. The purpose of this study was to determine whether complete myocardial surgical revascularization (CABG) documented by myocardial perfusion scintigraphy might alter the substrate responsible for LP. Prospectively, enrolled patients undergoing elective CABG were evaluated with thallium-201 myocardial perfusion scintigraphy and signal- averaged ECG pre- and postoperatively. SAECG recordings were obtained serially: before, 48-72 hours and 3 months after CABG. LPS were defined as positive if SAECG met at least two of Gomes criteria. Scintigraphies were performed pre- and 3 months postoperatively for determination of the success of revascularization. Changes observed in SAECG recordings after CABG were compared between those with and without successful revascularization. CABG resulted in successful revascularization in 23 patients and was unsuccessful in 17 (no change or deterioration of the perfusion defects). Preoperative SAECG values were not different between groups except for RMS values. The incidence of LP decreased significantly postoperatively in patients with improved myocardial perfusion, whereas there were no changes in patients who did not have postoperative perfusion improvement (McNemar test, P < 0.05). LPs disappear following the elimination of myocardial ischemia by complete surgical revascularization. Persistence of ischemia following CABG usually results in the persistence of late potentials. The incidence of ventricular arrhythmias is expected to be unchanged in these patients and they should be reevaluated for reinterventions.

Giant R-waves in a patient with an acute inferior myocardial infarction

We describe a case of a male patient with “giant” R-waves (GRWs) in association with an acute inferior myocardial infarction (MI). Such electrocardiogram (ECG) pattern has been associated heretofore with the hyperacute phase of an anterior MI, and unstable, and variant angina, although it is found in illustrations of many previous publications in conjunction with inferior MI. The GRWs, along with ST-segment elevations, were noted transiently in the inferior ECG leads, early in the clinical course of our patient. Subsequent evolution of the ECG revealed classic appearances for an inferior MI. Cardiac enzymes, and thallium-201 myocardial perfusion scintigraphy revealed evidence for inferiorly-located myocardial necrosis. Coronary arteriography showed stenosis of the right coronary artery, for which the patient underwent an uneventful angioplasty and “stenting” of the culprit vessel. The pathophysiology of the syndrome of GRWs is briefly discussed.

Long-term effects of the alpha, beta-blocker arotinolol on stable effort angina pectoris using 24-hour ambulatory electrocardiographic monitoring: an open-label, pilot study

Background: Beta-blockers are effective in patients with effort angina pectoris. However, there have been no previous reports on the long-term effects of beta-blocker therapy using ambulatory electrocardiographic (AECG) monitoring according to a MEDLINE ® search. Objective: This study was undertaken to assess the long-term effects of the alpha, beta-blocker arotinolol in patients with stable effort angina pectoris using AECG monitoring. Methods: This pilot study involved patients with Canadian Cardiovascular Society class I or II stable effort angina pectoris and left ventricular ejection fraction >40% assessed using 2-dimensional echocardiography in whom percutaneous transluminal coronary angioplasty and coronary artery bypass grafting had not been performed. Patients were excluded if they were >75 years of age, had congestive heart failure of New York Heart Association class III or IV, or had a confirmed diagnosis of an illness likely to shorten their life span (eg, cancer, cirrhosis). Effort angina pectoris was diagnosed based on chest pain on effort and myocardial ischemia as demonstrated by stress thallium-201 myocardial perfusion scintigraphy and significant ST-segment depression on exercise electrocardiogram. The alpha, beta-blocker arotinolol 20 mg/d, divided into 2 doses of 10 mg each, was administered orally for 2 years. Patients were seen by the same physician at 2-week intervals during the first 6 weeks of treatment and at 4-week intervals thereafter, at which times chest pain, nitrate consumption, blood pressure, and heart rate were assessed. AECG monitoring was performed before treatment, at 6 weeks, and after 2 years of treatment. Results: Results were assessable in 12 of 18 patients at 4 institutions (6 withdrew from the study within 4 weeks of treatment) with a mean (±SD) age of 65 ± 3 years. The number of episodes per day of chest pain decreased significantly ( P < 0.05) at 6 weeks and became rare 2 years after treatment. There was significant improvement ( P < 0.05) during the daytime at both 6 weeks and 2 years in the number of episodes (0.1 ± 0.4 and 0.1 ± 0.3, respectively, vs 0.9 ± 1.1) and the duration (3.8 ± 7.0 and 0.4 ± 1.6 minutes, respectively, vs 40.9 ± 27.8 minutes) of ST-segment depression. The incidence and duration of ST-segment depression decreased significantly ( P < 0.05) in the nighttime at 2 years compared with baseline (0.2 ± 0.04 and 0.04 ± 1.6 minutes vs 1.9 ± 0.9 and 23.9 ± 31.5 minutes, respectively). Daytime heart rate decreased significantly ( P < 0.05), from 84 ± 11 beats/min before treatment to 69 ± 12 beats/min at 6 weeks and 67 ± 12 beats/min at 2 years; nighttime heart rate also decreased significantly ( P < 0.05), from 70 ± 11 beats/min before treatment to 65 ± 9 beats/min at 6 weeks and 59 ± 7 beats/min at 2 years. Conclusions: Arotinolol improved the incidence and duration of ST-segment depression in patients with stable effort angina pectoris on AECG monitoring by decreasing heart rate. Because the improvement was more marked after 2 years than after 6 weeks, we concluded that arotinolol is beneficial in the long-term treatment of patients with stable effort angina pectoris, although a larger study using a control group is needed to confirm our results.

Effect of silicone breast implants on myocardial imaging.

The authors investigated the effect of silicone breast implants (SBIs) on thallium-201 myocardial perfusion scintigraphy. Twenty-nine patients with SBIs and 14 control subjects were included in the study. All of the participants underwent a resting thallium-201 myocardial perfusion study. Comparison of the thallium images between patients with SBI and control subjects was done both visually and semiquantitatively. On visual analysis, neither image distortion nor image artifact attributable to the SBIs was noted. Semiquantitative analysis revealed that in patients with SBIs, the uptake values of the anteroseptal, anterolateral, lateroanterior, and lateroinferior myocardial walls was slightly, but significantly, lower than those of control subjects: anteroseptal, 87.7+/-6.0% vs. 92.8+/-5.1%; anterolateral, 88.0+/-5% vs. 92.6+/-4.5%; lateroanterior, 87.4+/-5% vs. 91.4+/-4.7%; and lateroinferior, 86.0+/-6.0% vs. 91.7+/-7.0%. The uptake value of the remaining walls in patients with SBIs were not significantly different than the control subjects. In conclusion, SBIs did cause a significant decrease in uptake values of the myocardial walls, which should be considered during interpretation of the images.

Transient left posterior hemiblock during myocardial ischemia—eliciting exercise treadmill testing: A report of a case and a critical analysis of the literature

We describe a 75-year-old male patient with two-vessel coronary artery disease, who developed transient left posterior hemiblock (LPH) while undergoing an exercise treadmill test (ETT). The intraventricular conduction abnormality initially had the features of alternating LPH, which evolved to stable LPH prior to dissipating, and it occurred at the first minute of recovery. The exercise electrocardiogram and the associated thallium-201 myocardial perfusion scintigraphy (T1) revealed severe reversible myocardial ischemia. This rare occurrence is discussed in the context of the observed coronary lesions, the distribution of the radionuclide-detected ischemia, and the previous experience from the literature. An insight regarding the low prevalence of transient LPH is afforded, since the described case derives from a series of 2,160 consecutive patients who underwent ETT in conjunction with T1. Finally, a comment is provided on the complexities of deciphering the specific pathophysiologic mechanism(s) of transient LPH, occurring during ETT.