Safe Deferral of Coronary Computed Tomography Angiography for Patients With a Low Pretest Probability of Coronary Artery Disease in 2019 European Society of Cardiology Guidelines.

BACKGROUND: Coronary computed tomography angiography is increasingly used as the first-line test for suspected coronary artery disease. Its overuse in a low pretest probability (PTP) population may lead to low diagnostic yield without change in patient management. We evaluated the clinical consequences of the updated 2019 European Society of Cardiology (ESC) chronic coronary syndromes guidelines' PTP estimation and whether imaging could be safely deferred in patients with a low PTP. METHODS AND RESULTS: This retrospective cohort included all 1753 consecutive patients who underwent coronary computed tomography angiography for suspected coronary artery disease at Helsinki University Hospital between 2009 and 2017. PTP was calculated according to the 2013 and 2019 ESC guidelines. The overall mortality, cardiac deaths, myocardial infarctions, and hospitalizations for unstable angina were acquired from national registry data for 1 to 10 years of follow-up (median, 4 years). Updated 2019 ESC guidelines classified 72% of the patients as having low PTP, whose imaging could have been deferred. The revascularization rate (4.7%) and annual cardiac mortality (0.4%) were low in the 857 patients reclassified from the recommendation to test, according to the 2013 ESC guideline, to deferral of coronary computed tomography angiography, according to the new 2019 guideline. CONCLUSIONS: The updated 2019 ESC guideline PTP score aids clinicians in safely preventing the overuse of cardiac imaging in patients deemed at low PTP of coronary artery disease. Diagnostic yield, revascularization rate, and cardiac mortality are low in patients with low pretest risk.

Adenosine-induced splenic switch-off on [15O]H2O PET perfusion for the assessment of vascular vasodilatation.

BACKGROUND: Splenic switch-off (SSO) is a marker of adequate adenosine-induced vasodilatation on cardiac magnetic resonance perfusion imaging. We evaluate the feasibility of quantitative assessment of SSO in myocardial positron emission tomography (PET) perfusion imaging using [15O]H2O. METHODS: Thirty patients underwent [15O]H2O PET perfusion with adenosine stress. Time-activity curves, as averaged standardized uptake values (SUVavg), were extracted from dynamic PET for spleen and liver. Maximum SUVavg, stress and rest spleen-to-liver ratio (SLR), and the splenic activity concentration ratio (SAR) were computed. Optimal cut-off values for SSO assessment were estimated from receiver operating characteristics (ROC) curve for maximum SUVavg and SLR. Also, differences between coronary artery disease, myocardial ischemia, beta-blockers, and diabetes were assessed. Data are presented as median [interquartile range]. RESULTS: In concordance with the SSO phenomenon, both the spleen maximum SUVavg and SLR were lower in adenosine stress when compared to rest perfusion (8.1 [6.5, 9.2] versus 16.4 [13.4, 19.0], p < 0.001) and (0.81 [0.63, 1.08] versus 1.86 [1.73, 2.06], p < 0.001), respectively. During adenosine stress, the SSO effect was most prominent 40-160 s after radiotracer injection. Cut-off values of 12.6 and 1.57 for maximum SUVavg and SLR, respectively, were found based on ROC analysis. No differences in SAR, SLRRest, or SLRStress were observed in patients with coronary artery disease, myocardial ischemia, or diabetes. CONCLUSIONS: SSO can be quantified from [15O]H2O PET perfusion and used as a marker for adequate adenosine-induced vasodilatation response. In contrary to other PET perfusion tracers, adenosine-induced SSO is time dependent with [15O]H2O.

The Presence of Residual Vascular and Adipose Tissue Inflammation on 18F-FDG PET in Patients with Chronic Coronary Artery Disease.

Purpose: We evaluated the residual vascular and adipose tissue inflammation in patients with chronic coronary artery disease (CAD) using positron emission tomography (PET). Methods: Our study population consisted of 98 patients with known CAD and 94 control subjects who had undergone 18F-fluorodeoxyglucose (18F-FDG) PET due to non-cardiac reasons. Aortic root and vena cava superior 18F-FDG uptake were measured to obtain the aortic root target-to-background ratio (TBR). In addition, adipose tissue PET measurements were done in pericoronary, epicardial, subcutaneous, and thoracic adipose tissue. Adipose tissue TBR was calculated using the left atrium as a reference region. Data are presented as mean ± standard deviation or as median (interquartile range). Results: The aortic root TBR was higher in CAD patients compared to control subjects, 1.68 (1.55-1.81) vs. 1.53 (1.43-1.64), p < 0.001. Subcutaneous adipose tissue uptake was elevated in CAD patients 0.30 (0.24-0.35) vs. 0.27 (0.23-0.31), p < 0.001. Metabolic activity of CAD patients and control subjects was comparable in the pericoronary (0.81 ± 0.18 vs. 0.80 ± 0.16, p = 0.59), epicardial (0.53 ± 0.21 vs. 0.51 ± 0.18, p = 0.38) and thoracic (0.31 ± 0.12 vs. 0.28 ± 0.12, p = 0.21) adipose tissue regions. Aortic root or adipose tissue 18F-FDG uptake was not associated with the common CAD risk factors, coronary calcium score, or aortic calcium score (p value > 0.05). Conclusion: Patients with a chronic CAD had a higher aortic root and subcutaneous adipose tissue 18F-FDG uptake compared to control patients, which suggests residual inflammatory risk.

Cardiac sarcoidosis: phenotypes, diagnosis, treatment, and prognosis.

Cardiac sarcoidosis (CS) results from epithelioid cell granulomas infiltrating the myocardium and predisposing to conduction disturbances, ventricular tachyarrhythmias, and heart failure. Manifest CS, however, constitutes only the top of an iceberg as advanced imaging uncovers cardiac involvement 4 to 5 times more commonly than what is clinically detectable. Definite diagnosis of CS requires myocardial biopsy and histopathology, but a sufficient diagnostic likelihood can be achieved by combining extracardiac histology of sarcoidosis with clinical manifestations and findings on cardiac imaging. CS can appear as the first or only organ manifestation of sarcoidosis or on top of pre-existing extracardiac disease. Due to the lack of controlled trials, the care of CS is based on observational evidence of low quality. Currently, the treatment involves corticosteroid-based, tiered immunosuppression to control myocardial inflammation with medical and device-based therapy for symptomatic atrioventricular block, ventricular tachyarrhythmias, and heart failure. Recent outcome data indicate 90% to 96% 5-year survival in manifest CS with the 10-year figures ranging from 80% to 90%. Major progress in the care of CS awaits the key to its molecular-genetic pathogenesis and large-scale controlled clinical trials.

Cardiac magnetic resonance -detected myocardial injury is not associated with long-term symptoms in patients hospitalized due to COVID-19.

BACKGROUND: Long-term symptoms are frequent after coronavirus disease 2019 (COVID-19). We studied the prevalence of post-acute myocardial scar on cardiac magnetic resonance imaging (CMR) in patients hospitalized due to COVID-19 and its association with long-term symptoms. MATERIALS AND METHODS: In this prospective observational single-center study, 95 formerly hospitalized COVID-19 patients underwent CMR imaging at the median of 9 months after acute COVID-19. In addition, 43 control subjects were imaged. Myocardial scar characteristic of myocardial infarction or myocarditis were noted from late gadolinium enhancement images (LGE). Patient symptoms were screened using a questionnaire. Data are presented as mean ± standard deviation or median (interquartile range). RESULTS: The presence of any LGE was higher in COVID-19 patients (66% vs. 37%, p<0.01) as was the presence of LGE suggestive of previous myocarditis (29% vs. 9%, p = 0.01). The prevalence of ischemic scar was comparable (8% vs. 2%, p = 0.13). Only two COVID-19 patients (7%) had myocarditis scar combined with left ventricular dysfunction (EF <50%). Myocardial edema was not detected in any participant. The need for intensive care unit (ICU) treatment during initial hospitalization was comparable in patients with and without myocarditis scar (47% vs. 67%, p = 0.44). Dyspnea, chest pain, and arrhythmias were prevalent in COVID-19 patients at follow-up (64%, 31%, and 41%, respectively) but not associated with myocarditis scar on CMR. CONCLUSIONS: Myocardial scar suggestive of possible previous myocarditis was detected in almost one-third of hospital-treated COVID-19 patients. It was not associated with the need for ICU treatment, greater symptomatic burden, or ventricular dysfunction at 9 months follow-up. Thus, post-acute myocarditis scar on COVID-19 patients seems to be a subclinical imaging finding and does not commonly require further clinical evaluation.

Incidence and Predictors of Atrial Fibrillation in Cardiac Sarcoidosis: A Multimodality Imaging Study.

BACKGROUND: In cardiac sarcoidosis (CS), the risk and predictors of new-onset atrial fibrillation (AF) are poorly known. OBJECTIVES: The authors evaluated the incidence and characteristics of AF in newly diagnosed CS. METHODS: The authors studied 118 patients (78 women, mean age 50 years) with AF-naive CS having undergone cardiac 18F-fluorodexoyglucose positron emission tomography (18F-FDG PET) at the time of diagnosis. Details of patient characteristics and medical or device therapy were collected from hospital charts. The PET scans were re-analyzed for presence of atrial and ventricular inflammation, and coincident cardiac magnetic resonance (CMR) studies and single-photon emission computed tomography (SPECT) perfusions were analyzed for cardiac structure and function, including the presence and extent of myocardial scarring. Detection of AF was based on interrogation of intracardiac devices and on ambulatory or 12-lead electrocardiograms. RESULTS: Altogether 34 patients (29%) suffered paroxysms of AF during follow-up (median, 3 years) with persistent AF developing in 7 patients and permanent AF in 4. The estimated 5-year incidence of AF was 55% (95% CI: 34%-72%) in the 39 patients with atrial 18F-FDG uptake at the time of diagnosis vs 18% (95% CI: 10%-28%) in the 79 patients without atrial uptake (P < 0.001). In cause-specific Cox regression analysis, atrial uptake was an independent predictor of AF (P < 0.001) with HR of 6.01 (95% CI: 2.64-13.66). Other independent predictors were an increased left atrial maximum volume (P < 0.01) and history of sleep apnea (P < 0.01). Ventricular involvement by PET, SPECT, or CMR was nonpredictive. Symptoms of AF prompted electrical cardioversion in 12 patients (35%). Three of the 34 patients (9%) experiencing AF suffered a stroke versus none of those remaining free of AF. CONCLUSIONS: In newly diagnosed CS, future AF is relatively common and associated with atrial inflammation and enlargement on multimodality cardiac imaging.

Incidence of Sudden Cardiac Death and Life-Threatening Arrhythmias in Clinically Manifest Cardiac Sarcoidosis With and Without Current Indications for an Implantable Cardioverter Defibrillator.

BACKGROUND: Cardiac sarcoidosis (CS) predisposes to sudden cardiac death (SCD). Guidelines for implantable cardioverter defibrillators (ICDs) in CS have been issued by the Heart Rhythm Society in 2014 and the American College of Cardiology/American Heart Association/Heart Rhythm Society consortium in 2017. How well they discriminate high from low risk remains unknown. METHODS: We analyzed the data of 398 patients with CS detected in Finland from 1988 through 2017. All had clinical cardiac manifestations. Histological diagnosis was myocardial in 193 patients (definite CS) and extracardiac in 205 (probable CS). Patients with and without Class I or IIa ICD indications at presentation were identified, and subsequent occurrences of SCD (fatal or aborted) and sustained ventricular tachycardia were recorded, as were ICD indications emerging first on follow-up. RESULTS: Over a median of 4.8 years, 41 patients (10.3%) had fatal (n=8) or aborted (n=33) SCD, and 98 (24.6%) experienced SCD or sustained ventricular tachycardia as the first event. By the Heart Rhythm Society guideline, Class I or IIa ICD indications were present in 339 patients (85%) and absent in 59 (15%), of whom 264 (78%) and 30 (51%), respectively, received an ICD. Cumulative 5-year incidence of SCD was 10.7% (95% CI, 7.4%-15.4%) in patients with ICD indications versus 4.8% (95% CI, 1.2%-19.1%) in those without (χ2=1.834, P=0.176). The corresponding rates of SCD were 13.8% (95% CI, 9.1%-21.0%) versus 6.3% (95% CI, 0.7%-54.0%; χ2=0.814, P=0.367) in definite CS and 7.6% (95% CI, 3.8%-15.1%) versus 3.3% (95% CI, 0.5%-22.9%; χ2=0.680, P=0.410) in probable CS. In multivariable regression analysis, SCD was predicted by definite histological diagnosis (P=0.033) but not by Class I or IIa ICD indications (P=0.210). In patients without ICD indications at presentation, 5-year incidence of SCD, sustained ventricular tachycardia, and emerging Class I or IIa indications was 53% (95% CI, 40%-71%). By the American College of Cardiology/American Heart Association/Heart Rhythm Society guideline, all patients with complete data (n=245) had Class I or IIa indications for ICD implantation. CONCLUSIONS: Current ICD guidelines fail to distinguish a truly low-risk group of patients with clinically manifest CS, the 5-year risk of SCD approaching 5% despite absent ICD indications. Further research is needed on prognostic factors, including the role of diagnostic histology. Meanwhile, all patients with CS presenting with clinical cardiac manifestations should be considered for an ICD implantation.

Convolutional neural networks for detection of transthyretin amyloidosis in 2D scintigraphy images.

BACKGROUND: Transthyretin amyloidosis (ATTR) is a progressive disease which can be diagnosed non-invasively using bone avid [99mTc]-labeled radiotracers. Thus, ATTR is also an occasional incidental finding on bone scintigraphy. In this study, we trained convolutional neural networks (CNN) to automatically detect and classify ATTR from scintigraphy images. The study population consisted of 1334 patients who underwent [99mTc]-labeled hydroxymethylene diphosphonate (HMDP) scintigraphy and were visually graded using Perugini grades (grades 0-3). A total of 47 patients had visual grade ≥ 2 which was considered positive for ATTR. Two custom-made CNN architectures were trained to discriminate between the four Perugini grades of cardiac uptake. The classification performance was compared to four state-of-the-art CNN models. RESULTS: Our CNN models performed better than, or equally well as, the state-of-the-art models in detection and classification of cardiac uptake. Both models achieved area under the curve (AUC) ≥ 0.85 in the four-class Perugini grade classification. Accuracy was good in detection of negative vs. positive ATTR patients (grade < 2 vs grade ≥ 2, AUC > 0.88) and high-grade cardiac uptake vs. other patients (grade < 3 vs. grade 3, AUC = 0.94). Maximum activation maps demonstrated that the automated deep learning models were focused on detecting the myocardium and not extracardiac features. CONCLUSION: Automated convolutional neural networks can accurately detect and classify different grades of cardiac uptake on bone scintigraphy. The CNN models are focused on clinically relevant image features. Automated screening of bone scintigraphy images using CNN could improve the early diagnosis of ATTR.

Prognostic Value of 99mTc-HMDP Scintigraphy in Elderly Patients With Chronic Heart Failure.

BACKGROUND: This study evaluated the prevalence and prognostic significance of cardiac transthyretin amyloidosis (ATTR) diagnosed using 99mTc- hydroxymethylene-diphosphonate (99mTc-HMDP) scintigraphy in an elderly heart failure population. METHODS: This retrospective study included 335 patients aged >70 years with heart failure and who underwent 99mTc-HMDP scintigraphy due to non-cardiac reasons in three imaging centres in Finland (Kymenlaakso Central Hospital, Jorvi Central Hospital, and Meilahti University Hospital). A Perugini grade >2 and heart-to-contralateral ratio (H/CL) of ≥1.30 were considered positive for cardiac ATTR. The overall and cardiovascular mortality were obtained from the national statistical service (Statistics Finland). RESULTS: There were 234 deaths, of which 70 were classified as being due to cardiovascular causes during a median follow-up of 1 (1-3) year. Transthyretin amyloidosis was diagnosed in 22 patients (6.6%) using visual analysis and 17 patients using the H/CL ratio (5.1%). Patients with ATTR were older (85±5 vs 80±5 yrs; p=0.002) and had higher N-terminal pro-brain natriuretic peptide (NT-ProBNP) levels (1,451 [813-3,799] vs 6,192 [2,030-8,833] ng/L; p=0.02). Age, bone metastases, and glomerular filtration rate were independent predictors of overall mortality in multivariable analysis. Age, glomerular filtration rate, ≥grade 2 visual cardiac uptake, and H/CL ratio were independent predictors of cardiovascular mortality. CONCLUSIONS: Cardiac uptake suggestive of ATTR was found in 5% of elderly patients with chronic heart failure. The presence of cardiac uptake on bone scintigraphy did not convey independent prognostic value on overall mortality but was independently associated with cardiovascular mortality.

Atherosclerotic plaque characteristics on quantitative coronary computed tomography angiography associated with ischemia on positron emission tomography in diabetic patients.

Patients with diabetes mellitus (DM) may show diffuse coronary artery atherosclerosis on coronary computed tomography angiography (CTA). The present study aimed at quantification of atherosclerotic plaque with CTA and its association with myocardial ischemia on positron emission tomography (PET) in DM patients. Of 922 symptomatic outpatients without previously known coronary artery disease who underwent CTA, 115 with DM (mean age 65 ± 8 years, 58% male) who had coronary atherosclerosis and underwent both quantified CTA (QCTA) and PET were included in the study. QCTA analysis was performed on a per-vessel basis and the most stenotic lesion of each vessel was considered. Myocardial ischemia on PET was based on absolute myocardial blood flow at stress ≤ 2.4 ml/g/min. Of the 345 vessels included in the analysis, 135 (39%) had flow-limiting stenosis and were characterized by having longer lesions, higher plaque volume, more extensive plaque burden and higher percentage of dense calcium (37 ± 22% vs 28 ± 22%, p = 0.001). On univariable analysis, QCTA parameters indicating the degree of stenosis, the plaque extent and composition were associated with presence of ischemia. The addition of the QCTA degree of stenosis parameters (x2 36.45 vs 88.18, p < 0.001) and the QCTA plaque extent parameters (x2 88.18 vs 97.44, p = 0.01) to a baseline model increased the association with ischemia. In DM patients, QCTA variables of vessel stenosis, plaque extent and composition are associated with ischemia on PET and characterize the hemodynamic significant atherosclerotic lesion.

Prognostic significance of incidental suspected transthyretin amyloidosis on routine bone scintigraphy.

BACKGROUND: Transthyretin amyloidosis (ATTR) is an occasional incidental finding on bone scintigraphy. We studied its prognostic impact in elderly patients. METHODS: The study population consisted of 2000 patients aged over 70 years who underwent bone scintigraphies with clinical indications in three nuclear medicine departments (Kymenlaakso, Jorvi and Meilahti hospitals) in Finland. All studies were performed using 99mTechnetium labeled hydroxymethylene diphosphonate (HMDP). ATTR was suspected in patients with ≥grade 2 Perugini grade uptake (grade 0-3). Heart-to-contralateral ratio (H/CL) of ≥ 1.30 was considered positive for ATTR. The overall and cardiovascular mortality were obtained from the Finnish National Statistical Service. RESULTS: There were a total of 1014 deaths (51%) and 177 cardiovascular deaths (9%) during median follow-up of 4 ± 2 years. ATTR was suspected in 69 patients (3.6%) of which 54 (2.7%) had grade 2 and 15 (.8%) had grade 3 uptake and in 47 patients (2.4%) by H/CL ratio. In multivariate analyses age, bone metastasis, H/CL ratio and grade 3 uptake were independent predictors of overall and cardiovascular mortality. Grade 2 uptake was a predictor of cardiovascular mortality. CONCLUSIONS: A suspected ATTR as an incidental finding on bone scintigraphy predicts elevated overall and cardiovascular mortality in elderly patients.

The Accuracy of Left Ventricular and Left Atrial Volumetry Using 64-Slice Computed Tomography: In Vitro Validation Study With Human Cardiac Cadaveric Casts.

OBJECTIVE: We aimed to validate the accuracy of imaging of left atrial and ventricular volumes using cardiac cadaveric silicone casts. METHODS: Left atrial (n = 14) and ventricular (n = 15) casts were imaged using 64-slice computed tomography (CT). Water displacement (WD) of cardiac casts was used as the gold standard for volume measurements. RESULTS: Compared with WD, CT resulted in slightly higher left atrial and ventricular volumes (54 ± 25 vs 56 ± 26 mL [P = 0.003] and 57 ± 47 vs 66 ± 47 mL [P = 0.0001]). Variability between left atrial and ventricular volumes by CT and WD was low (coefficients of variation [CVs], 4% [intraclass correlation coefficient {ICC}, 0.99] and 12% [ICC, 0.97]). Intraobserver variability of CT was low for both the left atrium and the left ventricle (CVs, 1% [ICC, 1.00] and 4% [ICC, 1.00]). CONCLUSIONS: Cardiac CT is both accurate and reproducible in assessment of left ventricular and atrial chamber volumes.

Frequency and angiographic characteristics of coronary microvascular dysfunction in stable angina: a hybrid imaging study.

AIMS: Coronary microvascular dysfunction (CMD) can cause angina in the absence of obstructive coronary artery disease (CAD). We studied the frequency and angiographic characteristics of CMD in symptomatic patients with suspected stable CAD and identified CMD as diffusely abnormal coronary vasodilator capacity by positron emission tomography (PET) perfusion imaging. METHODS AND RESULTS: We recruited prospectively 189 patients with intermediate pre-test probability of CAD who underwent coronary computed tomography angiography and quantitative 15O-water PET perfusion imaging followed by invasive coronary angiography, and assessment of fractional flow reserve when feasible. Prevalence of obstructive epicardial CAD was 37%. Absolute myocardial blood flow was diffusely reduced (<2.4 mL/g/min) within the left ventricle during adenosine stress in 32 (17%) patients. In 15 (8%) patients, this was explained by three-vessel obstructive CAD, whereas the remaining 17 (9%) were diagnosed with CMD. Of these, 2 (1% of all patients) had no coronary atherosclerosis, 5 (3% of all patients) had non-obstructive atherosclerosis, and in 10 (5% of all patients) CMD co-existed with obstructive CAD. Atypical angina or non-anginal chest pain (53%) was the most common presentation. Older age and male sex were associated with CMD, but other risk factors of CAD were equally common in patients with or without CMD. CONCLUSION: Coronary microvascular dysfunction exists in 9% of symptomatic stable patients with suspected CAD. However, the prevalence of microvascular dysfunction without any coronary atherosclerosis is low (1%) in this population.

Coronary computed tomography angiography derived risk score in predicting cardiac events.

BACKGROUND: We evaluated the prognostic value of an integrated atherosclerosis risk score combining the markers of coronary plaque burden, location and composition as assessed by computed tomography angiography (CTA). METHODS: 922 consecutive patients underwent CTA for suspected coronary artery disease (CAD). Patients without atherosclerosis (n = 261) and in whom quantitative CTA analysis was not feasible due to image quality, step-artefacts or technical factors related to image acquisition or data storage (n = 153) were excluded. Thus, final study group consisted of 508 patients aged 63 ± 9 years. Coronary plaque location, severity and composition for each coronary segment were identified using automated CTA quantification software and integrated in a single CTA score (0-42). Adverse events (AE) including death, myocardial infarction (MI) and unstable angina (UA) were obtained from the national healthcare statistics. RESULTS: There were a total of 20 (4%) AE during a median follow-up of 3.6 years (9 deaths, 5 MI and 6 UA). The CTA risk score was divided into tertiles: 0-6.7, 6.8-14.8 and > 14.8, respectively. All MI (n = 5) and most of the other AE occurred in the highest risk score tertile (3 vs. 3 vs. 14, p = 0.002). After correction for age and gender, the CTA risk score remained independently associated with AE. CONCLUSIONS: Comprehensive CTA risk score integrating the location, burden and composition of coronary atherosclerosis predicts future cardiac events in patients with suspected CAD.

Prognostic Value of Coronary CT Angiography With Selective PET Perfusion Imaging in Coronary Artery Disease.

OBJECTIVES: The purpose of this study was to evaluate the prognostic value of sequential hybrid imaging strategy in which positron emission tomography (PET) perfusion imaging is performed selectively in patients with suspected obstructive coronary artery disease (CAD) on coronary computed tomography angiography (CTA). BACKGROUND: Coronary CTA is an accurate diagnostic test for excluding obstructive CAD. However, the positive predictive value is suboptimal. METHODS: We investigated 864 consecutive symptomatic patients with intermediate probability of CAD who adhered to the sequential imaging approach. PET myocardial perfusion imaging using 15O-labeled water during adenosine stress was performed when suspected obstructive stenosis was present on coronary CTA. The major adverse events (AEs) including all-cause mortality, myocardial infarction (MI), and unstable angina pectoris (UAP) were recorded. RESULTS: During a median follow-up of 3.6 years, 16 deaths, 10 MIs, and 5 UAPs occurred. Obstructive CAD was excluded by coronary CTA in 462 (53%) patients who had significantly lower annual AE rate than did patients with suspected obstructive stenosis on coronary CTA (0.4% vs. 1.5%; p = 0.003). The latter underwent PET study, on which 195 (49%) had normal and 207 had abnormal perfusion. The annual rate of AEs was 5 times higher in those with abnormal perfusion than with normal perfusion (2.5% vs. 0.5%; p = 0.004). Patients with normal perfusion had AE rate comparable to patients without obstructive CAD on coronary CTA (p = 0.77). CONCLUSIONS: In patients with suspected CAD obstructive disease can be excluded in 53% of patients by coronary CTA, and these patients have good outcome. About one-half (49%) of the remaining patients have normal perfusion and event rate comparable to patients without obstructive CAD on coronary CTA while patients with ischemia have clearly worse outcome. Sequential approach utilizing anatomical imaging by coronary CTA followed by selective functional perfusion imaging is a feasible strategy to diagnose and risk-stratify patients with suspected CAD.

Incidence of persistent renal dysfunction after contrast enhanced coronary CT angiography in patients with suspected coronary artery disease.

Contrast-induced nephropathy (CIN) is a potentially serious complication of contrast agents used in computed tomography angiography (CTA). The aim of this study was to evaluate whether persistent renal dysfunction occurs in patients undergoing coronary CTA for suspected stable coronary artery disease (CAD). From a cohort of 957 patients undergone coronary CTA, we identified 402 patients with plasma creatinine levels collected before and within 6 months after CTA. According to the definition of CIN, patients with a ≥25 % increase in plasma creatinine after CTA were evaluated. The post-CTA measurements in 402 patients (195 men, age 62.9 ± 9.3 years) were performed at a median of 99 days after CTA. On average, there was no change in plasma creatinine level between the pre- and post-CTA measurements (75.8 ± 16.0 and 75.7 ± 16.4 µmol/L, respectively; P = 0.63) but both increases and decreases were commonly detected. Fourteen (3.5 %) patients had a ≥25 % increase in plasma creatinine levels after CTA. A more detailed evaluation of these patients revealed that in 4 patients the increase was explained by other morbidities, whereas in 9 patients the creatinine level returned to the previous levels at later follow-up (median time to normalization: 311 days). Only in 1 (0.2 %) remaining patient, there was a persistent increase in plasma creatinine level, possibly related to the iodine contrast agent exposure. Alterations in plasma creatinine concentration occur frequently. Persistent renal dysfunction attributable to iodine contrast agent exposure is rare in patients referred to coronary CTA for suspected CAD.