Noninvasive assessment of coronary anatomy and myocardial perfusion: going toward an integrated imaging approach

[Association of Atrial Fibrillation with Coronary Lesion in Ischemic Heart Disease Patients]

AIM

to find out whether atrial fibrillation (AF) in patients with ischemic heart disease (IHD) is related to some definite localization or extent of coronary artery lesions or type of coronary circulation.

MATERIALS AND METHODS

We compared data of clinical, laboratory, and instrumental examination of 178 IHD patients from the Registry of coronary angiography of patients with AF (main group) and 331 patients (comparison group) selected according to propensity score matching with balancing by sex, age, body mass index, severity of chronic heart failure, frequency of myocardial infarctions, detection of arterial hypertension, and thyroid diseases.

RESULTS

The groups did not differ in terms of alcohol use, frequency of smoking, and detection of diabetes. Patients with AF compared with those without had higher mean heart rate (105±32 vs. 70±13 bpm, р<0.001), lower level of triglycerides (1.74±1.08 vs. 1.94±1.17 mmol / l, р=0.019). AF patients more rarely had class III-IV effort angina (52.9 % vs. 66.5 %, р=0.041). Rate of detection of left ventricular (LV) dilatation and index of LV asynergy in both groups were similar, but absolute dimensions and indexes of LV, left atrium, right ventricle, LV myocardial mass were higher in the AF group. Hemodynamically significant mitral regurgitation and lowering of LV contractility were more often detected in patients with AF (49.1 % vs. 18.4 %, р<0.001, and 56.2 % vs. 39.5 %, р<0.001, in main and comparison groups, respectively). Analysis of coronary angiography data showed that patients with compared with those without AF more often had right type of coronary circulation (87.5 % vs. 80.4 %, р=0.043) as well as lesions of the right coronary artery (92.1 % vs. 85.8 %, р=0.037), and less often lesions of left coronary artery trunk (16.3 % vs. 24.8 %, р=0.027).

CONCLUSION

AF in patients with IHD is associated with right coronary artery lesions and right type of coronary circulation.

Non-invasive Multimodality Cardiovascular Imaging of the Right Heart and Pulmonary Circulation in Pulmonary Hypertension

Pulmonary hypertension (PH) is defined as resting mean pulmonary arterial pressure (mPAP) ≥25 millimeters of mercury (mmHg) via right heart (RH) catheterization (RHC), where increased afterload in the pulmonary arterial vasculature leads to alterations in RH structure and function. Mortality rates have remained high despite therapy, however non-invasive imaging holds the potential to expedite diagnosis and lead to earlier initiation of treatment, with the hope of improving prognosis. While historically the right ventricle (RV) had been considered a passive chamber with minimal role in the overall function of the heart, in recent years in the evaluation of PH and RH failure the anatomical and functional assessment of the RV has received increased attention regarding its performance and its relationship to other structures in the RH-pulmonary circulation. Today, the RV is the key determinant of patient survival. This review provides an overview and summary of non-invasive imaging methods to assess RV structure, function, flow, and tissue characterization in the setting of imaging's contribution to the diagnostic, severity stratification, prognostic risk, response of treatment management, and disease surveillance implications of PH's impact on RH dysfunction and clinical RH failure.

Current and future trends in multimodality imaging of coronary artery disease

Nowadays, there is a wide array of imaging studies available for the evaluation of coronary artery disease, each with its particular indications and strengths. Cardiac single photon emission tomography is mostly used to evaluate myocardial perfusion, having experienced recent marked improvements in image acquisition. Cardiac PET has its main utility in perfusion imaging, atherosclerosis and endothelial function evaluation, and viability assessment. Cardiovascular computed tomography has long been used as a reference test for non-invasive evaluation of coronary lesions and anatomic characterization. Cardiovascular magnetic resonance is currently the reference standard for non-invasive ventricular function evaluation and myocardial scarring delineation. These specific strengths have been enhanced with the advent of hybrid equipment, offering a true integration of different imaging modalities into a single, simultaneous and comprehensive study.

Beyond ultrasound: advances in multimodality cardiac imaging

The rapid technological evolution accomplished in noninvasive cardiac imaging techniques over the past few decades has provided physicians with a large armamentarium for the evaluation of patients with known or suspected coronary heart disease. Noninvasive assessment of coronary artery calcium or noninvasive coronary angiography may be performed using computed tomography or magnetic resonance imaging. These techniques evaluate the presence of atherosclerosis rather than ischemia. Conversely, nuclear cardiology is the most widely used noninvasive approach for the assessment of myocardial perfusion and function. These techniques coupled with the development of dedicated image fusion software packages to merge data sets from different modalities have paved the way for hybrid imaging. This article provides a description of the available noninvasive imaging techniques in the assessment of coronary anatomy, myocardial perfusion, and cardiac function in patients with known or suspected coronary heart disease.

Myocardial perfusion scintigraphy and echocardiography for detecting coronary artery disease in hypertensive patients: a meta-analysis

PURPOSE

This meta-analysis summarized the accuracy of stress myocardial perfusion scintigraphy (MPS) and stress echocardiography for the diagnosis of coronary artery disease (CAD) in patients with arterial hypertension.

METHODS

We searched for studies in which stress MPS or stress echocardiography were performed to detect CAD in hypertensive patients, with coronary angiography used as the reference test, published from January 1980 to December 2010. Studies performed in patients with known CAD, acute coronary syndrome and previous revascularization procedures were excluded.

RESULTS

Of 1,263 studies, 13 met the inclusion criteria. Pooled summary estimates showed that stress MPS had a sensitivity of 0.90 [95% confidence interval (CI) 0.82-0.95] and a specificity of 0.63 (95% CI 0.53-0.72). For stress MPS, the area under the curve (AUC) at the summary receiver-operating characteristic (SROC) graph was 0.83 (95% CI 0.80-0.86). At meta-regression analysis, the presence of positive stress electrocardiography as inclusion criterion was the only significant effect modifier (p < 0.01). Pooled summary estimates showed that stress echocardiography had a sensitivity of 0.77 (95% CI 0.69-0.83) and a specificity of 0.89 (95% CI 0.83-0.93). For stress echocardiography, the AUC at SROC was 0.91 (95% CI 0.88-0.93). At the meta-regression analysis no significant effect modifier was detected.

CONCLUSION

MPS has high sensitivity for detecting CAD in hypertensive patients, with specificity comparable to that reported in the general population, whereas stress echocardiography shows higher specificity but substantially reduced sensitivity compared to MPS.

Relationship between obstructive coronary artery disease and abnormal stress testing in patients with paroxysmal or persistent atrial fibrillation

Atrial fibrillation (AF) has been linked to the presence of underlying coronary artery disease (CAD). However, whether the higher burden of CAD observed in AF patients translates into higher burden of myocardial ischemia is unknown. In 87 patients (71% male, mean age 61 ± 10 years) with paroxysmal or persistent AF and without history of CAD, MSCT coronary angiography and stress testing (exercise ECG test or myocardial perfusion imaging) were performed. CAD was classified as obstructive (≥50% luminal narrowing) or not. Stress tests were classified as normal or abnormal. A population of 122 patients without history of AF, similar to the AF group as to age, gender, symptomatic status and pre-test likelihood, served as a control group. Based on MSCT, 17% of AF patients were classified as having no CAD, whereas 43% showed non-obstructive CAD and the remaining 40% had obstructive CAD. A positive stress test was observed in 49% of AF patients with obstructive CAD. Among non-AF patients, 34% were classified as having no CAD, while 41% showed non-obstructive CAD and 25% had obstructive CAD (P = 0.013 compared to AF patients). A positive stress test was observed in 48% of non-AF patients with obstructive CAD. In conclusion, the higher burden of CAD observed in AF patients is not associated to higher burden of myocardial ischemia.

Role of cardiovascular imaging in systemic autoimmune diseases

Systemic autoimmune diseases are characterized by an excess of cardiovascular (CV) morbidity and mortality compared to the general population, mainly due to chronic inflammation that promotes the development of endothelial dysfunction and enhanced atherosclerosis. Early diagnosis of silent CV involvement is mandatory to improve the long term prognosis of these patients and CV imaging provides valuable information as a reliable diagnostic tool. Transthoracic echocardiography, with several applications (e.g. coronary flow reserve evaluation, tissue Doppler imaging, speckle tracking and the transesophageal approach), represents a first line evaluation, in association with biomarkers of endothelial dysfunction, such as asymmetric dimethylarginine. Nuclear medicine provides useful information on myocardial perfusion. The aim of this editorial is to provide a brief but complete review of the diagnostic tools available for screening and follow up of CV involvement in systemic autoimmune diseases.

Prognostic role of myocardial single photon emission computed tomography in the elderly

The increase in average life expectancy will move the burden of coronary artery disease (CAD) to older patients. Myocardial perfusion imaging by single photon emission computed tomography (SPECT) has been extensively validated for diagnosis and prognostic evaluation in large population series. Yet, its use is usually limited in elderly patients in whom, despite increased absolute cardiovascular risk, diagnostic and therapeutic work-up is often underperformed. American College of Cardiology/American Heart Association guidelines recommend exercise ECG testing as the initial noninvasive method for assessment of CAD in patients with a normal or near-normal resting ECG, regardless of age. However, a considerable proportion of elderly patients is unable to reach an adequate workload during the exercise test and the majority of those undergoing for standard exercise treadmill score are classified as intermediate risk. In elderly patients, SPECT imaging may provide valuable diagnostic and prognostic information for clinical management. In particular, normal or near normal SPECT identifies elderly patients at low risk of major adverse cardiac events at the short-term follow-up.

Relation between Framingham risk categories and the presence of functionally relevant coronary lesions as determined on multislice computed tomography and stress testing

Noninvasive assessment of subclinical atherosclerosis by multislice computed tomographic (MSCT) coronary angiography and demonstration of significant, flow-limiting coronary artery disease (CAD) by stress testing may improve patients' risk stratification. However, data relating the complementary information provided by these noninvasive techniques to traditional risk assessment are scarce. In 255 subjects (45% women, mean age 54 +/- 12 years) without known CAD, 64-slice MSCT coronary angiography and stress testing (exercise electrocardiographic test or myocardial perfusion imaging) were performed. Framingham risk score (FRS) was calculated from baseline characteristics (50% low, 22% intermediate, 28% high). Angiograms showing atherosclerosis were classified as obstructive (> or =50% luminal narrowing) CAD or not. Stress tests were classified as normal or abnormal. Multislice computed tomogram identified 155 patients (61%) with CAD, of whom 78 (31%) showed obstructive CAD. A positive stress test result was observed in 36 patients (46%) with obstructive CAD. In line with increasing FRS categories, a significant increase in the prevalence of functionally relevant obstructive CAD was observed (6% low vs 45% intermediate vs 63% high, p <0.001). In conclusion, a strong positive relation exists between FRS and prevalence of functionally relevant obstructive CAD. Selective use of MSCT coronary angiography and stress testing may refine the traditional risk assessment of CAD events, especially in patients deemed at intermediate and high risk.