Estimation of the collective ionizing dose in the Portuguese population for the years 2011 and 2012, due to nuclear medicine exams / Estimación de la dosis colectiva en la población portuguesa de los años 2011 y 2012, debido a los exámenes de medicina nuclear

Objectives. In 2009-2010 a Portuguese consortium was created to implement the methodologies proposed by the Dose Datamed II (DDM2) project, aiming to collect data from diagnostic X-ray and nuclear medicine (NM) procedures, in order to determine the most frequently prescribed exams and the associated ionizing radiation doses for the Portuguese population. The current study is the continuation of this work, although it focuses only on NM exams for the years 2011 and 2012. Material and methods. The annual frequency of each of the 28 selected NM exams and the average administered activity per procedure was obtained by means of a nationwide survey sent to the 35 NM centres in Portugal. Results. The results show a reduction of the number of cardiac exams performed in the last two years compared with 2010, leading to a reduction of the annual average effective dose of Portuguese population due to NM exams from 0.08 mSv ± 0.017 mSv/caput to 0.059 ± 0.011 mSv/caput in 2011 and 0.054 ± 0.011 mSv/caput in 2012. Portuguese total annual average collective effective dose due to medical procedures was estimated to be 625.6 ± 110.9 manSv in 2011 and 565.1 ± 117.3 manSv in 2012, a reduction in comparison with 2010 (840.3 ± 183.8 manSv). Conclusions. The most frequent exams and the ones that contributed the most for total population dose were the cardiac and bone exams, although a decrease observed in 2011 and in 2012 was verified. The authors intend to perform this study periodically to identify trends in the annual Portuguese average effective dose and to help to raise awareness about the potential dose optimization (AU)

Objetivo. En 2009 y 2010 un consorcio portugués ha sido creado para implementar las metodologías propuestas por el proyecto europeo Datamed II (DDM2), con el objetivo de coleccionar datos de procedimientos de radiología de diagnóstico y medicina nuclear (MN) más frecuentes, así como la dosis asociada en la población portuguesa. Este estudio es una continuación del trabajo, que se centrará en los datos de MN para los años de 2011 y 2012. Material y Métodos. La frecuencia anual de cada uno de los 28 exámenes de MN seleccionados y la actividad media administrada por procedimiento se obtuvieron a través de una encuesta enviada a los 35 departamentos de MN en Portugal. Resultados. Los resultados muestran una reducción drástica en el número de procedimientos cardiacos en los últimos dos años, lo que tiene como consecuencia una reducción de la dosis efectiva anual en la población portuguesa derivado de procedimientos de MN de 0,08mSv±0,017 mSv/caput en 2010, a 0,059±0,011 mSv/caput in 2011 y 0,054±0,011 mSv/caput in 2012. La dosis efectiva colectiva media en la población portuguesa es estimada en 625.6 ± 110.9 manSv en 2011, y 565.1 ± 117.3 manSv en 2012. Conclusiones. Los exámenes cardiacos y óseos fueron más frecuentes y los que más contribuyeron para la dosis total de la población, aunque se verificó una disminución en 2011 y en 2012. Los autores de este trabajo pretenden realizar este tipo de estudios periódicamente para identificar tendencias en los diferentes procedimientos de MN y ayudar a aumentar la conciencia de los profesionales de MN sobre este asunto (AU)

Estimation of the collective ionizing dose in the Portuguese population for the years 2011 and 2012, due to nuclear medicine exams.

OBJECTIVES: In 2009-2010 a Portuguese consortium was created to implement the methodologies proposed by the Dose Datamed II (DDM2) project, aiming to collect data from diagnostic X-ray and nuclear medicine (NM) procedures, in order to determine the most frequently prescribed exams and the associated ionizing radiation doses for the Portuguese population. The current study is the continuation of this work, although it focuses only on NM exams for the years 2011 and 2012. MATERIAL AND METHODS: The annual frequency of each of the 28 selected NM exams and the average administered activity per procedure was obtained by means of a nationwide survey sent to the 35 NM centres in Portugal. RESULTS: The results show a reduction of the number of cardiac exams performed in the last two years compared with 2010, leading to a reduction of the annual average effective dose of Portuguese population due to NM exams from 0.08 mSv ± 0.017 mSv/caput to 0.059 ± 0.011 mSv/caput in 2011 and 0.054 ± 0.011 mSv/caput in 2012. Portuguese total annual average collective effective dose due to medical procedures was estimated to be 625.6 ± 110.9 manSv in 2011 and 565.1 ± 117.3 manSv in 2012, a reduction in comparison with 2010 (840.3 ± 183.8 manSv). CONCLUSIONS: The most frequent exams and the ones that contributed the most for total population dose were the cardiac and bone exams, although a decrease observed in 2011 and in 2012 was verified. The authors intend to perform this study periodically to identify trends in the annual Portuguese average effective dose and to help to raise awareness about the potential dose optimization.

Synthesis, chelating properties towards gallium and biological evaluation of two N-substituted 3-hydroxy-4-pyridinones.

Two N-substituted 3-hydroxy-4-pyridinones (1-(3'-aminopropyl)-3-hydroxy-2-methyl-4-pyridinone (L1) and 1-(2'-carboxyethyl)-3-hydroxy-2-methyl-4-pyridinone (L2)) were prepared through one- and three-step reactions, respectively. The pKa values of the ligands and the stability constants of their Ga(III) complexes have been determined. Both the complexes are strongly coordinated to three (O,O) hydroxypyridonate moieties. There is a clear effect of the N-substituents in the lipophilic-hydrophilic balance and in the Ga(III) binding interaction; the acid derivative (L2) has lower lipophilicity but higher chelating strength than the amine derivative (L1). Both chelators are shown to interfere in the typical biological behavior of 67Ga-citrate in mice: L1 enhanced the urinary excretion leading to an increased 67Ga removal from the soft tissue, while L2 induced a lower blood clearance with a pronounced bone uptake mainly at 48 h after injection, thus suggesting that the 67Ga-L2 complex could have potential interest as a bone imaging agent.

Role of myocardial ischemia and left ventricular wall motion abnormalities as contributory factors in the genesis of exercise-induced ST-segment elevation in Q-wave myocardial infarction.

In patients with a previous myocardial infarction, controversy exists regarding the significance of postexercise ST-segment elevation in the infarct-related leads. Although usually admitted to be a sign of left ventricular dysfunction or myocardial aneurysm, other studies however have related this finding to transient myocardial ischemia and to the presence of jeopardized but viable myocardium in the infarct area. The aim of the present study was to assess the significance of postexercise ST-segment elevation in Q-wave leads as a marker of transmural ischemia or left ventricular dysfunction in 36 consecutive patients, 16 with exercise-induced ST-segment elevation in infarct-related leads. Patients were evaluated by treadmill exercise testing, coronary angiography and ventriculography, thallium-201 tomographic scintigraphy and radionuclide ventriculography within 3 months of the first myocardial infarction. Sixteen patients (group I) had exercise-induced ST segment elevation and 20 (group II) postexercise inversion, no change or pseudonormalization of the T wave in infarct-related leads. The study showed no difference in infarct-related artery, vessel disease or luminal diameter stenosis in groups I and II. The overall agreement between ST shifts and myocardial perfusion in the infarct area was 30.56% with a kappa coefficient of -0.33 (p = NS). The overall agreement between ST shifts and wall motion abnormalities was 69.44% with a kappa coefficient of 0.39 (p < 0.01), stress-induced ST-segment elevation being associated with severe wall contractile disorders in 85% of the patients. In conclusion stress-induced ST-segment elevation in Q wave leads, although not a marker of wall motion abnormalities, is associated with akinesia or dyskinesia of the left ventricular wall.

Post-exercise electrocardiographic alterations, ST-segment elevation and QTc changes in patients with recent myocardial infarction.

UNLABELLED: Stress-induced ST-segment elevation and a prolongation or no change of the QTc ratio (corrected QT interval for heart rate) at maximal exercise in the infarct leads have been associated with the presence of residual myocardial ischemia in the infarct zone. The aim of this study was to test the agreement between stress-induced ST-segment elevation and post-exercise QTc changes in infarct leads, in 36 consecutive patients, studied by coronariography, radionuclide ventriculography and thallium-201 scintigraphy, within 3 months of the acute myocardial infarction. Sixteen patients (Group I) had exercise-induced ST-segment elevation in the infarct leads and 20 did not (Group II). The study showed no significant difference between severity of vessel disease and occlusion, prevalence of the infarct related artery or left ventricular dysfunction in Group I and II. No agreement between ST-segment shifts and myocardial perfusion in the infarct zone was found. Resting wall motion abnormalities were more severe in Group I than in Group II (p < 0.01). In the total of the 36 patients there was no agreement between ST-segment shifts and QTc-variations. The study showed agreement between QTc changes and myocardial perfusion in the infarct area (K = 0.64) (p < 0.001). CONCLUSION: This study showed no relation between post-exercise ST elevation and post-exercise QTc variations in Q wave leads. QTc variations at the end of exercise in the infarct related leads identified residual ischemia. Exercise ST segment elevation, although not a marker of ischemia, is associated with more severe wall motion abnormalities in the infarct zone.

Human polyclonal immunoglobulin labelled with technetium-99m via NHS-MAG3: a comparison of radiochemical behavior and biological efficacy with other labelling methods.

The aim of this study was to evaluate the radiochemical behavior, biological distribution, and localization in infection sites in mice of a human polyclonal immunoglobulin (HIG) labelled with 99mTc by a novel MAG3-labelling method. The resulting [99mTc]MAG3-HIG was compared with [99mTc]HIG preparations radiolabelled directly via 2-mercaptoethanol (2-Me) or stannous ion (Sn) reduction and indirectly via 2-iminothiolane (2-Im) conjugation. All preparations showed similar UV and radioactivity HPLC profile to that of native HIG except for 2-Im-HIG, which showed aggregates. The stabilities of the label to challenge with cysteine were similar for all the preparations. By nondenaturing SDS-PAGE, all preparations other than MAG3-HIG showed evidence of lower molecular weight fragments. The tissue distribution 4 and 24 h after intravenous administration of the four preparations were compared in mice previously administered with an isolate of Staphylococcus aureus in one thigh. The pharmacokinetics varied among the different preparations. When prepared via 2-Me, Sn, and 2-Im, both blood clearance and urinary excretion were faster than that of labelled MAG3-HIG. The absolute uptake in the infected thigh at 24 h was significantly higher for HIG labelled via MAG3 and 2-Me vs. the remaining methods. The infected thigh/normal thigh radioactivity ratios were similar at both time points for labelled HIG prepared via 2-Me, 2-Im, and NHS-MAG, methods but was significantly lower at 24 h for HIG prepared via Sn. The radioactive HPLC profiles of serum at 4 and 24 h were similar to that of the radiolabelled injectates. Based on these data we conclude that each radiolabelled HIG preparation studied showed increased localization in infectious foci although [99Tc]MAG3-HIG showed superior radiochemical and biological characteristics under the conditions of this investigation.

Technetium-99m labelling of the IOR CEA 1 monoclonal antibody: evaluation of different methods.

AIM: The aim of this study was to investigate the in vivo and in vitro properties of 99mTc labelled monoclonal antibody, IOR CEA 1 when radiolabelled by different methods. METHODS: To achieve that purpose IOR CEA was directly radiolabelled via 2-mercaptoethanol (2-Me) and stannous ion (SnCl2) reduction and indirectly via the 2-iminothiolane (2-Im) conjugation. The resulting 99mTc-MoAbs were analysed for number of free sulfhydryl groups, chemical and radiochemical purity (checked by HPLC and SDS PAGE), immunoreactivity and biological distribution in mice. RESULTS: Experimental results indicated a similar radiochemical purity and immunoreactivity for direct labelling methods and a decrease of both for 2-Im method. 2-Me antibody reduction led to a high antibody fragmentation as indicated by non-denaturing SDS PAGE analysis. Nevertheless SnCl2 and 2-Im labels revealed lower in vivo stability. CONCLUSION: 99mTc-(2-Me) IOR CEA presented favorable in vitro and in vivo properties. Therefore this label was compared to 99mTc-monoclonal antibody BW 431/26. Similar characteristics were found. Clinical studies also revealed identical biodistribution profile.

Comparison between dobutamine echocardiography and thallium-201 scintigraphy in detecting residual stenosis, ischemia, and necrosis in patients with prior myocardial infarction.

BACKGROUND: Following the first attempts to detect myocardial ischemia with two-dimensional echocardiography stress testing, pharmacologic stress using dobutamine infusion has become an alternative to echocardiography exercise testing for evaluation of coronary artery disease. It has been shown that stress echocardiography has a diagnostic accuracy similar to that of an exercise thallium test. Other studies, however, indicated that radionuclide myocardial perfusion imaging was more sensitive than exercise or pharmacologic stress echocardiography for detection of ischemia or jeopardized myocardium. HYPOTHESIS: The aim of the present study was to determine the ability of dobutamine stress echocardiography in comparison with thallium-201 scintigraphy to identify multivessel disease and the presence of myocardial scar and ischemia in 60 consecutive patients who suffered a first myocardial infarction (MI). METHODS: Patients were evaluated by coronary angiography and ventriculography, thallium-201 (201TI) tomographic scintigraphy, and dobutamine echocardiography within 3 months of a first MI. Forty-seven had Q-wave MI and 13 had non-Q-wave MI. Eleven patients were excluded from final analysis-7 because of failure to achieve target heart rate in spite of the use of atropine, and 4 because of high blood pressure following the infusion of dobutamine. RESULTS: Dobutamine echocardiography showed an overall sensitivity of 43% for detection of coronary artery lesions of 50-74% diameter stenosis and 201TI scintigraphy showed a sensitivity of 71%. For detection of lesions of > or = 75% diameter stenosis, dobutamine echocardiography showed a sensitivity of 52% and 201TI a sensitivity of 70%. Overall agreement between wall motion and myocardial perfusion for detection of necrosis and/or ischemia in the infarct area was 40.4% with a kappa coefficient of 0.09 (p = 0.13). For detection of ischemic myocardium outside the infarct zone, overall agreement was 78.6% with a kappa coefficient of 0.49 (p < 0.0001). CONCLUSION: Dobutamine echocardiography results showed a lower sensitivity than myocardial perfusion images in predicting multivessel coronary artery disease, and there was poor agreement between both methods in identifying necrosis or ischemia.

[Coronary artery disease, myocardial perfusion and ventricular function in Q-wave and non-Q-wave myocardial infarcts]. / Doença arterial coronária, perfusão miocárdica e função ventricular em enfartes do miocárdio com onda Q e sem onda Q.

Controversy remains in considering non-Q wave myocardial infarction (NQMI) a distinct pathophysiological entity of Q wave myocardial infarction (QMI). In order to analyze the severity of coronary artery disease, extension of myocardial scar or myocardial ischemia and ventricular function, 78 consecutive patients with QMI and 32 with NQMI, mean age 55.4 +/- 8.5, not submitted to thrombolytic therapy, were studied. Coronary angiography, exercise thallium scintigraphy and radionuclide ventriculography were performed in all at least within 3 months of a prior myocardial infarction. In the present study the occurrence of QMI was significantly more frequent in older patients than NQMI. There was no prevalence of occlusion either in the right, left circumflex or left anterior descending coronary arteries in both groups. Ejection fraction, degree of occlusion and presence of collateral circulation showed an equal prevalence in QMI and NQMI patients. A higher incidence of multivessel disease was found in NQMI that had less necrosis than QMI patients. The prevalence of exercise induced thallium-201 redistribution defects within the infarct zone was substantially higher and involved more scar segments in NQMI patients. Physiological and clinical consequences of coronary thrombosis depends on the size and the number of diseased arteries, the approach the pathophysiologic consequences of coronary disease in terms of fractal structure has been suggested. A pronounced heterogeneity in regional myocardial blood flow in a fractal branching arterial network may be responsible for the pathophysiologic differences of coronary thrombosis between Q-wave and non Q-wave infarction.

Technetium-99m tetrofosmin rest/stress myocardial SPET with a same-day 2-hour protocol: comparison with coronary angiography. A Spanish-Portuguese multicentre clinical trial.

Technetium-99m tetrofosmin (Myoview) has unique properties for myocardial perfusion imaging very early after injection of the tracer. We used a very short same-day rest/stress protocol, to be performed within 2 h and evaluated its diagnostic accuracy. The study included 144 patients from seven Spanish and four Portuguese centres with a diagnosis of uncomplicated coronary artery disease (CAD); 78 patients (54%) had no history of prior myocardial infarction. Patients were injected with /=50%) was achieved with a sensitivity of 64% for the left anterior descending artery, 49% for the left circumflex artery and 86% for the right coronary artery, and an accuracy of 71%, 72% and 73% respectively. Concordance of SPET and CA was 62% for single-vessel disease and 68% for multivessel disease. In conclusion, this Spanish-Portuguese multicentre clinical trial confirmed, in a considerable number of patients who underwent coronary angiography, the feasibility of 99mTc tetrofosmin (Myoview) rest/stress myocardial SPET using a very short protocol (2 h).

Wall motion abnormalities and late ventricular arrhythmia during the predischarge phase of acute myocardial infarction.

BACKGROUND: Left ventricular wall aneurysm is a complication of acute myocardial infarction which has been considered a precipitating factor of cardiac failure and ventricular arrhythmia. We have evaluated the relation between severe left ventricular wall motion abnormalities and ventricular arrhythmia. METHODS: During a two-year period 146 patients admitted to a coronary care unit with acute myocardial infarction were studied. Radionuclide angiography performed within the second and the fourth weeks was used to analyse phase and wall motility changes, and patients were divided into three groups: 1) Hypokinesia and/or akinesia localized to one segment: with no or slight changes in phase image--102 patients; 2) Aneurysm: left ventricular deformity with well-defined chromatic changes in phase image--19 patients; and 3) Dyskinesia and/or extensive akinesia of two or more segments: phase image with diffuse heterogeneous changes--25 patients. Ventricular arrhythmia was studied using Holter electrocardiography taken during the second week of acute myocardial infarction. Three rhythmic profiles were considered: no premature ventricular contractions--41 patients; with three or more than three premature ventricular contractions per hour--38 patients; repetitive premature ventricular contractions--20 patients. RESULTS: Premature ventricular contractions were absent in 31 (30%) of the patients with hypokinesia/localized akinesia vs 8 (42%) of the patients with aneurysm, and vs 2 (8%) of the patients with dyskinesia/extensive akinesia. Premature ventricular contractions were frequent (> or = 3/h) in 22 (22%) of the patients with hypokinesia/localized akinesia vs 4 (21%) of the patients with aneurysm (p = 0.35; NS), and vs 12 (48%) of the patients with dyskinesia/extensive akinesia (p=0.003). Repetitive premature ventricular contractions were present in 10 (10%) of the patients with hypokinesia/localized akinesia vs 2 (11%) of the patients with aneurysm, and vs 8 (32%) of the patients with dyskinesia/extensive akinesia (p=0.008). CONCLUSIONS: We conclude that the presence of aneurysm was not associated with a higher occurrence of ventricular arrhythmia, but patients with dyskinesia/extensive akinesia had a higher occurrence of ventricular arrhythmia, > or = 3 premature ventricular contractions per hour and repetitive premature ventricular contractions. Our results suggest that ventricular arrhythmia is related to functionally severe wall motion abnormalities, and not to anatomical discriminants. This finding leads us to suggest different electrophysiological mechanisms behind these two entities.

Minimal residual coronary obstructions in patients who suffered a first myocardial infarction. A prospective study comparing coronary angiography and exercise thallium scintigraphy.

The purpose of the present study was to correlate the presence of minimal coronary obstruction (< or = 50%) assessed by coronary angiography with the presence of myocardial scar and ischemia detected by thallium-201 myocardial perfusion imaging. The study included 83 consecutive patients (74 men and 9 women) with a mean age 55.4 +/- 8.5 years who suffered a first myocardial infarction and did not undergo thrombolytic therapy. In all patients, coronary angiography, left ventriculography, and exercise thallium-201 tomographic scintigraphy were performed within 3 to 5 months of the myocardial infarction. Coronary arteriograms showed minimal residual obstructions in 37 (45%) patients. Of a total of 54 patients with < or = 50% obstruction, 18 showed persistent defects and 22 reversible defects on thallium scintigrams. The present study showing estimated angiographic stenosis of < or = 50% as being responsible either for myocardial scar or myocardial ischemia on postexercise thallium scintigrams leads us to conclude that percent value of stenosis does not accurately predict the pathophysiologic significance of coronary atherosclerotic lesions in patients who suffer a myocardial infarction. After a first myocardial infarction, coronary angiographies and thallium-201 scintigrams are complementary for an optimal treatment strategy for selected subsets of patients.

Postexercise changes of the QTc interval in patients with recent myocardial infarction.

A lack of the QTc ratio decrease at maximal exercise is considered as an index of exercise-induced ischemia in patients with coronary artery disease. The authors studied 51 patients with recent myocardial infarction in order to evaluate the QTc changes with exercise in assessing the presence of remaining ischemic myocardium. All patients were submitted to exercise stress tests, coronary angiographies, and exercise thallium 201 scintigraphies within 3-5 months of the myocardial infarction. Of the patients studied, 18 showed one-vessel disease and 33 showed multivessel disease. All vessels were classified as patent or occluded. In all patients with reversible thallium 201 defects both at distance and in the infarct zone, the QTc interval following exercise either showed a prolongation or no change from the resting electrocardiogram. In patients with only fixed perfusion defects, the QTc shortened at the end of the test. This study showed a low sensitivity and specificity for inducible ST-segment depression compared with the delayed redistribution on the postexercise thallium 201 scintigram. QTc variations at the end of exercise electrocardiograms are valuable as a noninvasive, low-cost identification of residual ischemic myocardium in patients after myocardial infarction.

[Significance exercise-induced ST elevation in patients with myocardial infarction]. / Significado do supradesnivelamento ST de esforço em doentes com enfarte do miocárdio.

In 52 patients with previous myocardial infraction, 49 men and 3 women (mean age 56 +/- 7.1 years) the significance of ST-segment elevation during the stress-test, was evaluated. Of the 52 patients 15 (29%) showed St-segment elevation and 37(71%), showed no alteration of the ST-segment. Extension of coronary disease, degree of obstruction, wall motion abnormalities and the presence of residual ischemia were evaluated by coronary angiography, technetium-99M pyrophosphate imaging and exercise TL-201 scintigraphy. From the results of the study one may conclude that, in patients with previous myocardial infraction exercise, ST-segment elevation is a consequence of sub-occlusion of the left anterior descending coronary artery with severe ventricular dysfunction either in patients with one or multiple vessel disease.

Transient Crossed Aphasia: a Case Study with SPECT.

A 45-year-old right-handed man developed "crossed" anomie aphasia, neglect and inaccurate reaching of his left arm in both hemispaces due to a right parietal haemorrhage. Aphasia cleared in a few days. SPECT failed to demonstrate crossed left hemispheric diaschisis. This report emphasizes the importance of evaluating patients in the acute stage and of coupling "static" and "functional" imaging methods when studying brain-behavior relationships.

[Equilibrium radionuclide angiography in patients with previous myocardial infarct. Correlation with electrocardiogram and coronarography]. / Angiografia de radionuclídos de equílibrio em doentes com enfarte do miocárdio prévio. Correlação com o electrocardiograma e a coronariografia.

Fifty five patients with previous myocardial infarction (MI), 47 male and 8 female, mean age 55.5 +/- 8.9 years, have been studied in order to correlate the alterations found on the equilibrium (gated) radionuclide angiogram (RNA) with the location of the MI on the electrocardiogram of the obstructive lesions on coronary angiographies. Of the 55 patients studied, 22% showed no regional wall motion abnormalities (WMA). Both MI with and without Q wave may show WMA, which are significatively more frequent in patients with anterior MI on the ECG and with occlusive lesions (greater than 90%) on coronariographies. Regional localization of the WMA on the RNA does not identify the localization of the obstructive lesions. Hypokinesia was the most frequent type of WMA found both with occlusive (greater than 90%) and sub-occlusive (greater than 75%) lesions. Low values of the ejection fraction (less than 45%) were found in the presence of WMA and occlusive artery lesions.

[Surgical treatment of variant angina. Apropos of a clinical case]. / Terapêutica cirúrgica na angina variante. A propósito de um caso clínico.

A case of a male 66 years-old patient who presented with a clinical picture of Prinzmetal's variant angina early in the evolution of an acute myocardial infarction is reported. Transient elevation of ST-segment was documented on Holter monitoring in association with angina at rest as well as asymptomatic episodes of ST-segment changes. Significant two-vessels obstructive lesions (left anterior descending and circumflex arteries) was present. As variant angina had several recurrences in spite of medical therapy with nitrates and calcium antagonists, the patient was submitted to coronary by-pass surgery associated to plexectomy. A Thallium myocardial scintigraphy suggests that a peroperative infarction had occurred. The patient was asymptomatic at six months follow-up.

[Comparison of Holter electrocardiography and thallium 201 scintigraphy in the detection of myocardial ischemia]. / Comparação entre a electrocardiografia de Holter e a cintigrafia com tálio 201 na detecção de isquemia miocárdica.

OBJECTIVE OF THE STUDY: To compare ischemic changes (I) detected by Holter ECG (H ECG) to the myocardial perfusion defects found in 201 TI myocardial perfusion scintigraphy. DESIGN: 201 TI exercise test was made during the performance of a 24 hours H ECG. The validation of ST segment changes detected by H ECG during the exercise test was made on basis of reversible myocardial perfusion defects (RPD) detected on 201 TL and a relation between ST segment changes detected during the remaining 24 hours recording period and 201 TI (TI) RPD was established. SETTING: The patients (pt) included in the study have come from Cardiology and Heart Surgery Clinics of a Central teaching hospital. MATERIAL AND METHODS: 20 pt with a high coronary artery disease prevalence have been submitted to a two lead (V5 and aVF) 24 hour H ECG during which they have performed a symptom limited bicycle exercise test followed by an injection of 201 TI with acquisition 5 minutes later. Ischemic episodes detected on H ECG were quantified and their relation with heart rate and symptoms was established. As far as 201 TI studies are concerned the fixed and reversible perfusion defects as well as their location were evaluated. RESULTS: 1. H ECG: 6 pt (30%) presented ST changes on H ECG during the exercise test and a total of 9 pt (45%) had ST changes during exercise and during the remaining period of H ECG. 2. TI: 19 pt presented perfusion defects images (fixed in 7, reversible in 14, both kinds of defects in 7). 3. H ECG validation: H ECG during exercise presented I in 6 out of 14 pt with RPD on TI (sensitivity = 43%). Six of these 8 pt, with negative H and positive TI, had a chronic myocardial infarction. All the 6 pt with negative TI had negative H ECG (specificity = 100%). 4. H ECG TI comparison: 7 (50%) of the 14 pt with RPD had ST changes on 24 hrs H ECG. Seven of 11 pt with negative H ECG had RPD in TI. Two pt with negative TI had positive H ECG. These 2 pt had during H ECG a higher heart rate (HR) than the HR recorded during the exercise test. CONCLUSIONS: 1. In pt with known CAD, TI has a high sensitivity and specificity to show perfusion defects. 2. Considering TI as gold standard, H ECG showed to be a useful method to detect I in the studied population (sens. = 43%; spec. = 100%). 3. H ECG revealed to be an important diagnostic tool in detecting additional I episodes beyond the ones recorded during TI exercise test.