Myocardial Scintigraphy in the Evaluation of Cardiac Events in Patients without Typical Symptoms / Cintilografia Miocárdica na Avaliação de Eventos Cardíacos em Pacientes sem Sintomas Cardíacos Típicos

AbstractBackground:Cardiovascular disease is a leading cause of death in the world and in Brazil. Myocardial scintigraphy is an important noninvasive method for detecting ischemia in symptomatic patients, but its use in asymptomatic ones or those with atypical symptoms is yet to be defined.Objective:To verify the presence of major cardiac events in asymptomatic patients or those with atypical symptoms (atypical chest pain or dyspnea) that underwent myocardial scintigraphy (MS), over a period of 8 years. Secondary objectives were to identify cardiac risk factors associated with myocardial scintigraphy abnormalities and possible predictors for major cardiac events in this group.Methods:This was a retrospective, observational study using the medical records of 892 patients that underwent myocardial scintigraphy between 2005 and 2011 and who were followed until 2013 for assessment of major cardiac events and risk factors associated with myocardial scintigraphy abnormalities. Statistical analysis was performed by Fisher’s exact test, logistic regression and Kaplan-Meyer survival curves, with statistical significance being set at p ≤ 0.05.Results:Of the total sample, 52.1% were men, 86.9% were hypertensive, 72.4% had hyperlipidemia, 33.6% were diabetic, and 12.2% were smokers; 44.5% had known coronary artery disease; and 70% had high Framingham score, 21.8% had moderate and 8% had low risk. Of the myocardial scintigraphies, 58.6% were normal, 26.1% suggestive of fibrosis and 15.3% suggestive of ischemia. At evolution, 13 patients (1.5%) had non-fatal myocardial infarction and six individuals (0.7%) died. The group with normal myocardial scintigraphy showed longer period of time free of major cardiac events, non-fatal myocardial infarction (p = 0.036) and death. Fibrosis in the myocardial scintigraphy determined a 2.4-fold increased risk of non-fatal myocardial infarction and five-fold higher risk of death (odds ratio: 2.4 and 5.7, respectively; p = 0.043).Conclusion:The occurrence of major cardiac events in 8 years was small. Patients with fibrosis at MS had more major events, whereas patients with normal MS result had fewer major cardiac events, with higher survival.

ResumoFundamento:A doença cardiovascular é uma das principais causas de óbito no Brasil e no mundo. A cintilografia miocárdica tem papel estabelecido na detecção de isquemia de pacientes sintomáticos, mas sua indicação em assintomáticos ou naqueles com sintomas atípicos ainda não está definida.Objetivo:Identificar eventos maiores em pacientes assintomáticos ou com sintomas atípicos (dor torácica atípica ou dispneia) que realizaram cintilografia miocárdica, em até 8 anos. Como objetivos secundários, citamos identificar os fatores de risco associados às alterações na cintilografia miocárdica e os possíveis preditores para eventos maiores nesse grupo.Métodos:Estudo retrospectivo, observacional, por revisão de prontuário, de 892 pacientes que realizaram cintilografia miocárdica entre 2005 e 2011, com seguimento até 2013, para avaliação de eventos maiores e análise dos fatores de risco associados à cintilografia miocárdica alterada. A análise estatística foi realizada por testes de Fisher, regressão logística e curva de sobrevida de Kaplan-Meier, com p significativo se ≤ 0,05.Resultados:Do total dos pacientes da amostra, 52,1% eram homens, 86,9% hipertensos, 72,4% dislipidêmicos, 33,6% diabéticos, e 12,2% tabagistas; 44,5% tinham doença arterial coronária conhecida; e 70% apresentavam escore de Framingham alto, 21,8% moderado e 8% baixo risco. Das cintilografias miocárdicas, 58,6% foram normais; 26,1%, sugestivas de fibrose; e 15,3%, de isquemia. Na evolução, 13 pacientes (1,5%) apresentaram infarto do miocárdio não fatal e 6 pacientes (0,7%) foram a óbito. O grupo com cintilografia miocárdica normal apresentou maior tempo livre de eventos maiores, infarto do miocárdio não fatal (p = 0,036) e morte (p = 0,019). A fibrose determinou risco 2,4 vezes maior de infarto do miocárdio não fatal e cinco vezes maior de morte (odds ratio: 2,4 e 5,7, respectivamente; p = 0,043).Conclusão:A ocorrência de eventos maiores em até 8 anos no grupo estudado foi pequena. Pacientes com fibrose na cintilografia miocárdica apresentaram mais eventos maiores. Pacientes com cintilografia miocárdica normal apresentaram menos eventos maiores, com sobrevida maior.

Nitroglycerine-augmented myocardial perfusion scintigraphy for the assessment of prognosis and myocardial viability

The aims of this study were to determine the prognostic value and the accuracy of nitrate-augmented Tc-99m myocardial SPECT for myocardial viability detection. Patients with angiographic CAD and LV wall motion abnormality by MUGA were included in the study. Rest Tc-99m sestamibi SPECT MPS was performed on two consecutive days, once with 0.6 mg sublingual nitroglycerin and once without. Perfusion was graded semi-quantitatively. Reversibility score was calculated as the difference between nitrate-augmented and rest imaging perfusion scores. Repeat rest SPECT MPS was performed after at least 6 months and all patients were followed up for at least 12 months to determine the occurrence of cardiac events. Thirty-five patients were included in the study. Five patients died from myocardial infarction during the follow-up period. Eleven patients had follow-up SPECT, with five of them done after revascularization. Defect score improved significantly after revascularization compared without revascularization (7.4 versus 0.3, p=0.02). Reversibility scores correlated poorly with the subsequent occurrence of cardiac events in patients treated medically. There was no significant increase in LVEF detected after revascularization even if the patients had a positive reversibility score. By this parameter, nitrate-augmented MPS could not accurately assess myocardial viability. However, with nitrate-augmentation, defect scores significantly improved and were more predictive of post-revascularization scores compared to the rest scores. These suggest the possibility for enhanced detection of potentially viable myocardium with nitrate MPS. And due to its simplicity and safety, the routine use of nitrate-augmentation in clinical practice may be recommended.

Imaging Improves Diagnosis of Dementia with Lewy Bodies

Dementia with Lewy bodies (DLB) is the second most common cause of degenerative dementia after Alzheimer's disease (AD), and is clinically characterized by the progressive cognitive decline with fluctuations in cognition and alertness, recurrent visual hallucinations and Parkinsonism. Once these characteristic symptoms of DLB emerge, discriminating it from AD is relatively easy. However, in the early disease stages, the clinical symptoms of various types of dementias largely overlap and it is difficult to distinguish DLB from other neurodegenerative dementias based on clinical manifestations alone. To increase the accuracy of antemortem diagnosis of DLB, the latest diagnostic criteria incorporate findings from 123I-metaiodobenzylguanidine (MIBG) myocardial scintigraphy, or from neuroimaging such as computed tomography (CT), magnetic resonance imaging (MRI), single photon emission computed tomography (SPECT), and positron emission tomography (PET). In the present guidelines, decreased dopamine transporter uptake revealed by SPECT or PET receives the greatest importance among various neuroimaging findings and is listed as one of the suggestive features. Supportive features that commonly present but are not proven to have diagnostic specificity include relatively-preserved medial-temporal-lobe structures, occipital hypoperfusion, and abnormal MIBG myocardial scintigraphy. In this paper, we review the major findings on various neuroimaging modalities and discuss the clinical usefulness of them for the diagnosis of DLB. Although there is not enough evidence to reach the conclusion, considering the accessibility in clinical practice, in our personal views, we recommend the use of brain-perfusion SPECT and MIBG myocardial scintigraphy to improve the diagnosis of DLB.

Imaging Improves Diagnosis of Dementia with Lewy Bodies

Dementia with Lewy bodies (DLB) is the second most common cause of degenerative dementia after Alzheimer's disease (AD), and is clinically characterized by the progressive cognitive decline with fluctuations in cognition and alertness, recurrent visual hallucinations and Parkinsonism. Once these characteristic symptoms of DLB emerge, discriminating it from AD is relatively easy. However, in the early disease stages, the clinical symptoms of various types of dementias largely overlap and it is difficult to distinguish DLB from other neurodegenerative dementias based on clinical manifestations alone. To increase the accuracy of antemortem diagnosis of DLB, the latest diagnostic criteria incorporate findings from 123I-metaiodobenzylguanidine (MIBG) myocardial scintigraphy, or from neuroimaging such as computed tomography (CT), magnetic resonance imaging (MRI), single photon emission computed tomography (SPECT), and positron emission tomography (PET). In the present guidelines, decreased dopamine transporter uptake revealed by SPECT or PET receives the greatest importance among various neuroimaging findings and is listed as one of the suggestive features. Supportive features that commonly present but are not proven to have diagnostic specificity include relatively-preserved medial-temporal-lobe structures, occipital hypoperfusion, and abnormal MIBG myocardial scintigraphy. In this paper, we review the major findings on various neuroimaging modalities and discuss the clinical usefulness of them for the diagnosis of DLB. Although there is not enough evidence to reach the conclusion, considering the accessibility in clinical practice, in our personal views, we recommend the use of brain-perfusion SPECT and MIBG myocardial scintigraphy to improve the diagnosis of DLB.

Incremental prognostic value of perfusion defects in patients with scintigraphic evidence of left ventricular dysfunction

Patients with LV dysfunction are known to have a high risk for future coronary events. This study aimed to determine the incremental prognostic value of perfusion defects in patients with scintigraphic evidence of LV dysfunction. Patients showing either transient ischemic dilatation or Tl-201 lung:heart ratio of >0.5 on exercise or dipyridamole SPECT Tl- 201 myocardial perfusion scan were included in the study. Perfusion defects were scored semiquantitatively using a 17 -segment, 5-point scale (0 = normal, 4 = absent uptake). The extent and severity of defects were quantified using number of abnormal segments (NAS) and the summed stress score (SSS). Defect reversibility was quantified using the summed difference score (SDS) between stress and rest defects. Patients were followed up for the development of coronary events over a period of 12 - 30 months. There were 6 cardiac deaths and 7 myocardial infarctions in the 65 patients included in the study (20% overall event rate). ROC curve analysis of the scores revealed the following suggested cut-off values for predicting cardiac event: NAS ~ 7 (85% sensitivity, 56% specificity), SSS ~ 19 (77% sensitivity, 67% specificity) and SDS ~ 7 (31 % sensitivity, 60% specificity). ,Event rate was significantly higher above the cut-off value in SSS «19 = 9%, >19 = 32%,p = 0.04). With NAS, the event rate was higher above the cut-off value, with the difference approaching significance (NAS 7 = 26%, P = 0.06). There was no statistically significant difference in the event rate with high or low SDS (SDS 7 = 16%, P = 0.32). The odds ratios for NAS and SSS (5.8,4.9, respectively) were higher compared with SDS (0.56). The extent and severity of stress perfusion defects provided incremental prognostic information in patients with LV dysfunction. Our data suggest that the degree of defect reversibility showed no prognostic value in this subset of patients.

Assessment of cardiac sympathetic neuronal integrity using iodine-123 metaiodobenzylguanidine myocardial scintigraphy and its clinical efficacy as a new noninvasive screening test for the diagnosis of coronary artery spasm

BACKGROUND: It has been suggested that the sympathetic nervous system might play an important role in the development of coronary artery spasm. Recently, advances have made possible the imaging of the cardiac adrenergic nervous system with metaiodobenzylguanidine (MIBG) labeled with iodine-123. The purpose of this study was to assess the presence and location of abnormal sympathetic innervation by iodine-123-metaiodobenzylguanidine single-photon emission computed tomography (SPECT) and to evaluate the clinical efficacy of iodine-123-MIBG SPECT as a noninvasive screening test in patients with coronary artery spasm. METHOD: Coronary arteriography and provocative test with intravenous administration of ergonovine maleate were performed in 26 patients (21 men, 5 women, mean age 49.1+/-9.3, range: 26-59) who were suspected of having a coronary artery spasm. The subjects were divided into 2 groups ; Group 1 comparised of 18 patients subjects to the positive provocative test, Group 2 comparised of 8 patients subjects to the negative provocative test. Four healthy subjects served as control. All patients also underwent iodine-123-MIBG SPECT for the evaluation of cardiac sympathetic integrity. The SPECT findings were qualitatively evaluated by two experienced physicians who were blind to the clinical data. RESULTS: Abnormal sympathetic nervous innervation using iodine-123-MIBG SPECT was observed either as a reduced uptake or defect pattern in the perfused areas in 13 of the 18 vessels of ergonovine induced vasospasm. Normal sympathetic innervation as evidenced by normal iodine-123-MIBG uptake was noted in all of the 60 segments of normal vessel territories. Reduced uptake of iodine-123-MIBG was not detected in the perfused areas of five vasospasm-induced vessels (perfusion territory of LAD in 2 and the RCA in 3 patients). The sensitivity and specificity of iodine-123-MIBG for detection coronary artery spasm were 72.2% (95% confidence interval [CI] 55% to 89%) and 100%, respectively. The positive predictive value and negative predictive value were 100% and 92.3% (95% CI 91% to 93%), respectively. CONCLUSION: Iodine-123-MIBG SPECT is a feasible method to noninvasively evaluate and localize the territories of coronary arteries with spasms. Invasive diagnostic coronary arteriography with ergonovine provocation test may be unnecessary for the diagnosis of coronary artery spasm in patients with typical resting pain, negative exercise test or normal thallium perfusion scan, but abnormal iodine-123-MIBG SPECT.

Cintilografia de perfusäo miocárdica associada ao estresse farmacológico com dipiridamol / Scintigraphy of myocardial perfusion combined with pharmacologic stress with dipyridamole

PURPOSE--To analyze adverse reactions (AR), hemodynamic and electrocardiographic changes and thallium scintigraphy (TS) results, during pharmacological stress with dipyridamole (SD), correlating these data to the presence and extension of coronary artery disease (CAD). METHODS--We studied 126 patients, 66 had no evidence of cardiovascular disease (G1) and 60 had critical occlusive CAD > or = 70 per cent stenosis (G2). Most of them were male, mean age 56.5 +/- 10.9 years old. All patients were submitted to TS after receiving 0.56 mg/kg of dipyridamole intravenously (0.14 mg/min during 4 min) followed by 111MBq of thallium-chloride-201. Conventional ECG was recorded before and after SD; heart rate (HR) and arterial pressure (AP) were monitored during dipyridamole infusion. All signals and/or symptoms were observed. RESULTS--Cine-coronarography showed 22 patients (37 per cent ) with one vessel disease (VD) (G2a), 26 (46 per cent ) with two VD (G2b) and 12 (20 per cent ) with three VD (G2c). Of the 126 patients 63 per cent did not present symptoms. Flushing (25 per cent ) and sick-headache (12 per cent ) were most frequent AR. Typical angina was reported by one G1 patient (1.5 per cent ) and six G2 patients (10 per cent ) (p < 0.05). HR increased 18.09 +/- 12.27 per cent and 12.40 +/- 4.90 per cent , systolic blood pressure varied -5.2 +/- 7.5 per cent and -4.3 +/- 6.5 per cent in G1 and G2, respectively. These parameters are not correlated to CAD presence and extension. ST depression and ectopic beats occurred in 5 per cent and 11 per cent of G1 patients, in 15 per cent and 30 per cent of G2 patients, respectively (p < 0.05). Typical angina was more common in G2a and G2b; ST changes in G2b and G2c; and arrhythmia in G2c (not significant). Sensitivity of TS associated to SD was 84 per cent , comparable to stress exercise thallium test. CONCLUSION--TS associated to SD, a noninvasive, safe with low morbidity and few collateral effects method is an option to patients with limitations to physical exercise tests