Effective radiation dose of three diagnostic tests in cardiology: single photon emission computed tomography, invasive coronary angiography and cardiac computed tomography angiography.

INTRODUCTION: Diagnostic tests that use ionizing radiation play a central role in cardiology and their use has grown in recent years, leading to increasing concerns about their potential stochastic effects. The aims of this study were to compare the radiation dose of three diagnostic tests: single photon emission computed tomography (SPECT), invasive coronary angiography (ICA) and cardiac computed tomography (cardiac CT) and their evolution over time, and to assess the influence of body mass index on radiation dose. METHODS: We assessed consecutive patients included in three prospective registries (SPECT, ICA and cardiac CT) over a period of two years. Radiation dose was converted to mSv and compared between the three registries. Differences over time were evaluated by comparing the first with the fourth semester. RESULTS: A total of 6196 exams were evaluated: 35% SPECT, 53% ICA and 22% cardiac CT. Mean radiation dose was 10.7±1.2 mSv for SPECT, 8.1±6.4 mSv for ICA, and 5.4±3.8 mSv for cardiac CT (p<0.001 for all). With regard to the radiation dose over time, there was a very small reduction in SPECT (10.7 to 10.5 mSv, p=0.004), a significant increase (25%) in ICA (7.0 to 8.8 mSv; p<0.001), and a significant reduction (29%) in cardiac CT (6.5 to 4.6 mSv, p<0.001). Obesity was associated with a significantly higher radiation dose in all three exams. CONCLUSIONS: Cardiac CT had a lower mean effective radiation dose than invasive coronary angiography, which in turn had a lower mean effective dose than SPECT. There was a significant increase in radiation doses in the ICA registry and a significant decrease in the cardiac CT registry over time.

Coronary computed tomography angiography-adapted Leaman score as a tool to noninvasively quantify total coronary atherosclerotic burden.

To describe a coronary computed tomography angiography (CCTA)-adapted Leaman score (CT-LeSc) as a tool to quantify total coronary atherosclerotic burden with information regarding localization, type of plaque and degree of stenosis and to identify clinical predictors of a high coronary atherosclerotic burden as assessed by the CT-LeSc. Single center prospective registry including a total of 772 consecutive patients undergoing CCTA (Dual-source CT) from April 2011 to March 2012. For the purpose of this study, 581 stable patients referred for suspected coronary artery disease (CAD) without previous myocardial infarction or revascularization procedures were included. Pre-test CAD probability was determined using both the Diamond-Forrester extended CAD consortium method (DF-CAD consortium model) and the Morise score. Cardiovascular risk was assessed with the HeartScore. The cut-off for the 3rd tercile (CT-LeSc ≥8.3) was used to define a population with a high coronary atherosclerotic burden. The median CT-LeSc in this population (n = 581, 8,136 coronary segments evaluated; mean age 57.6 ± 11.1; 55.8 % males; 14.6 % with diabetes) was 2.2 (IQR 0-6.8). In patients with CAD (n = 341), the median CT-LeSc was 5.8 (IQR 3.2-9.6). Among patients with nonobstructive CAD, most were classified in the lowest terciles (T1, 43.0 %; T2, 36.1 %), but 20.9 % were in the highest tercile (T3). The majority of the patients with obstructive CAD were classified in T3 (78.2 %), but 21.8 % had a CT-LeSc in lower terciles (T1 or T2). The independent predictors of a high CT-LeSc were: Male sex (OR 1.73; 95 % CI 1.04-2.90) diabetes (OR 2.91; 95 % CI 1.61-5.23), hypertension (OR 2.54; 95 % CI 1.40-4.63), Morise score ≥ 16 (OR 1.97; 95 % CI 1.06-3.67) and HeartScore ≥ 5 (OR 2.42; 95 % CI 1.41-4.14). We described a cardiac CT adapted Leaman score as a tool to quantify total (obstructive and nonobstructive) coronary atherosclerotic burden, reflecting the comprehensive information about localization, degree of stenosis and type of plaque provided by CCTA. Male sex, hypertension, diabetes, a HeartScore ≥5 % and a Morise score ≥ 16 were associated with a high coronary atherosclerotic burden, as assessed by the CT-LeSc. About one fifth of the patients with nonobstructive CAD had a CT-LeSc in the highest tercile, and this could potentially lead to a reclassification of the risk profile of this subset of patients identified by CCTA, once the prognostic value of the CT-LeSc is validated.

[Primary PCI in ST-elevation myocardial infarction: mode of referral and time to PCI]. / ICP primária no enfarte de miocárdio com supradesnivelamento do segmento ST: tempo para intervenção e modos de referenciação.

INTRODUCTION: According to the current guidelines for treatment of ST-elevation myocardial infarction (STEMI), percutaneous coronary intervention (PCI) should be performed within 90 min of first medical contact and total ischemic time should not exceed 120 min. The aim of this study was to analyze compliance with STEMI guidelines in a tertiary PCI center. METHODS: This was a prospective single-center registry of 223 consecutive STEMI patients referred for primary PCI between 2003 and 2007. RESULTS: In this population (mean age 60±12 years, 76% male), median total ischemic time was 4h 30 min (<120 min in 4% of patients). The interval with the best performance was first medical contact to first ECG (median 8 min, <10 min in 59% of patients). The worst intervals were symptom onset to first medical contact (median 104 min, <30 min in 6%) and first ECG to PCI (median 140 min, <90 min in 16%). Shorter total ischemic time was associated with better post-PCI TIMI flow, TIMI frame count and ST-segment resolution (p<0.03). The three most common patient origins were two nearby hospitals (A and B) and the pre-hospital emergency system. The pre-hospital group had shorter total ischemic time than patients from hospitals A or B (2h 45 min vs. 4h 44 min and 6h 40 min, respectively, p<0.05), with shorter door-to-balloon time (89 min vs. 147 min and 146 min, respectively, p<0.05). CONCLUSIONS: In this population, only a small proportion of patients with acute myocardial infarction underwent primary PCI within the recommended time. Patients referred through the pre-hospital emergency system, although a minority, had the best results in terms of early treatment. Compliance with the guidelines translates into better myocardial perfusion achieved through primary PCI.