Ahmed Aljizeeri

Assessment of myocardial blood flow and coronary flow reserve with positron emission tomography in ischemic heart disease: current state and future directions

Positron emission tomography (PET) is a versatile imaging technology that allows assessment of myocardial perfusion, both at a spatially relative scale and also in absolute terms, thereby enabling noninvasive evaluation of myocardial blood flow (MBF) and coronary flow reserve (CFR). Assessment of MBF using FDA-approved PET isotopes, such as 82Rb and 13N-ammonia, has been well validated, and several software packages are currently available, thereby allowing for MBF evaluation to be incorporated into routine workflow in contemporary nuclear laboratories. Incremental diagnostic and prognostic information provided with the knowledge of MBF has the potential for widespread applications. Improving the ability to identify the true burden of obstructive epicardial coronary stenoses and allowing for noninvasive assessment of coronary micro circulatory function can be achieved with MBF assessment. On the other hand, attenuated CFR has been shown to predict adverse cardiovascular prognosis in a variety of clinical settings and patient subgroups. With expanding applications of MBF, this tool promises to provide unique insight into the integrity of the entire coronary vascular bed beyond what is currently available with relative perfusion assessment. This review intends to provide an in-depth discussion of technical and clinical aspects of MBF assessment with PET as it relates to patients with ischemic heart disease.

An Increasing Population with Metabolic Syndrome and/or Diabetes Mellitus in the Middle East—Is There an Added Value of Coronary Calcium Scoring to Myocardial Perfusion Imaging?

The population of the Middle East is a growing population characterized by increasing prevalence of metabolic syndrome, diabetes, and obesity. Both myocardial perfusion imaging (MPI) and coronary artery calcification (CAC) have a well-validated role in the diagnosis and prognosis of coronary artery disease (CAD). In the recent years, adding CAC score to myocardial perfusion imaging has been associated with incremental diagnostic and prognostic value. The aim of this paper is to review the diagnostic and prognostic value of adding CAC score to nuclear MPI in the Middle Eastern patients in the face of increasing prevalence of metabolic syndrome and CAD risk factors. Since limited local data are available from the Middle East, this review will focus on reports on similar cohorts from the western world.

Preferential vascular effects of amlodipine in reducing stiffness in muscular not elastic arteries in essential hypertension & the metabolic syndrome

Introduction Arterial stiffness and wave reflection are independent prognosticators of cardiovascular morbidity and mortality. There are two types off arteries in the body; elastic and muscular. The elastic arteries receive the blood directly from the heart while the muscular arteries distribute the blood to various organs of the body. The elasticity of the major arteries decreases with age and therefore may play a key role in the development and control of hypertension and subsequently the choice of drug therapy. The aim of the study is to evaluate the effects of the amlodipine, on arterial stiffness in essential hypertension, compared to hydrochlorothiazide. Methodology We randomised 24 hypertensive patients hypertension (clinic blood pressure (BP) > 140/90 mmHg and ambulatory >135/85 mmHg) to amlodipine 5 mg or hydrochlorothiazide 12.5 mgs in a single blind parallel group study for one month and measured aortic pulse wave velocity (PWV) and augmentation index (AIx) at baseline and one month after treatment. The patients were studied fasting, having abstained from smoking, caffeinated beverages and alcohol 12 h prior to the measurements. Brachial BP and heart rate (Omron), pulse wave velocity (PWV, Complior) and augmentation index (AIx, SphymoCor), a measure of wave reflection, were measured in the supine position after a rest of 15 min. Results were analysed with JMP (SAS for Windows) using Wilcoxon-Rank Sums test and ANOVA. Results are expressed as mean ± SEM, p  Results Both drugs produced a similar reduction in brachial BP but there was a greater reduction in the aortic systolic BP (20 ± 3 vs 7 ± 2 mmHg, p  Conclusion This short-term study suggests that the effects of amlodipine on arterial stiffness are primarily on muscular rather than elastic arteries. This should be kept in mind when choosing the HTN treatment in elderly and those with diseases affecting the aorta.

INCREMENTAL PROGNOSTIC VALUE OF CORONARY CALCIUM SCORING IN PATIENTS UNDERGOING 82-RUBIDIUM MYOCARDIAL PERFUSION IMAGING

Introduction: Coronary artery calcium (CAC) score and hyperaemic myocardial blood flow (HMBF) have been associated with clinical outcomes. The aim of this analysis is to determine the incremental prognostic value of CAC over HMBF in the prediction of cardiac events. Methods: A total of 2,060

Finding a gatekeeper to coronary angiography: a step in the right direction

In recent years, coronary computed tomography angiography (CCTA) has come to the forefront in the evaluation of patients with chest pain. Multiple large scale randomized clinical trials (RCT) confirmed its high sensitivity and negative predictive value.In addition, multicentre registries and RCTs confirmed its ability to triage patients with acute and chronic chest pain. Its high negative predicative value resulted in a low rate of referral to coronary angiography over a 3-year period in patients with normal or non-obstructive disease. However, its ability to accurately quantify stenotic lesions and obstructive CAD, particularly in intermediate lesions, is limited. This is expected to increase post-CCTA resource utilization especially in patients with intermediate lesions. Data from the Medicare claims data in the USA suggested that using CCTA as the assessment tool of Medicare patients was associated with increased referral to the coronary angiography compared to other non-invasive modalities. Similarly, a meta-analysis of RCT of CCTA in acute chest pain showed increased rate of angiography and revascularization without impacting outcomes. This could be in part due to the fact that anatomical stenosis does not necessarily correlate with haemodynamically significant stenosis. In the FAME study, 65% of angiographically intermediate lesions were not haemodynamically significant while 20% of initially thought obstructive (71–90%) anatomical lesions had normal fractional flow reserve (FFR). Recent technological advances with CCTA-derived FFR (FFRCT) or CT myocardial perfusion imaging Computed Tomography Perfusion (CTP) allows to partially overcome these limitations. The diagnostic accuracy of FFRCT is high and is comparable to angiography alone. However, despite its incremental diagnostic and prognostic value, FFRCT has some limitations including off-site performance, extra cost, and other logistic issues limiting its widespread use. In contrast, CTP can be performed on-site, but requires vasodilator stress agent. Adding CTP to CCTA has been associated with improved diagnostic accuracy of CCTA similar to a combination of angiography and single photon emission tomography (SPECT). Similarly, major adverse clinical events (MACE) and event-free survival from combination of CCTA and CTP were not different from the combination of angiography and SPECT. In this issue of the journal, Van Rosendael et al. report on the impact of adding CTP to CCTA on downstream referral to Invasive coronary angiography (ICA), revascularization and outcome in patients with stable new-onset chest pain. As per protocol, patients with normal CCTA did not undergo CTP. However, in patients with intermediate or high grade stenosis, CTP was performed. Thus, nearly one-third of the 384 patients referred for CCTA were found to have >_ 50% stenosis and subsequently underwent CTP. Similar to previously reported data from nuclear imaging, almost half of the patients with significant anatomical stenosis had normal CTP. The rate of ICA and revascularization was much higher in patients with abnormal CTP compared to normal CTP. However, major adverse cardiovascular events rate in patients with obstructive CAD and normal CTP were low. Thus, supporting the concept that in patients with anatomical but no physiological disease, deferring angiography and revascularization is safe. Performing CCTA and sequential CTP reduced the rate of referral to ICA (five-fold reduction) and revascularization. This well conducted study demonstrated the feasibility of 1-day CCTA/CTP protocol and affirmed the role of CCTA in accurately ruling out CAD with limited radiation dose (7.5 mSv). It has also shown that the positive productive value of CCTA can be improved with CTP resulting in selective referral to angiography. Adopting such technique as a gate keeper would potentially improve post-CCTA angiography yield. The study also confirmed prior observations that nearly 50% of obstructive lesions on CCTA are not associated with ischaemia on physiologic testing. Adopting this approach would also provide an opportunity to evaluate the patient prognosis based on the presence of ischaemia and high-risk plaques. However, there are still many unanswered questions prior to a wide adoption of this approach in routine clinical practice. It appears that compared to invasive angiography, CTP was normal in 15% of patients requiring clinically indicated revascularizations and nearly 32% of patients with multi-vessel disease had normal CTP. This might

Temporal trends in the referral pattern to and yield of cardiac MRI: an analysis from Saudia Arabia

Results A total of 1,581 patients (38% females) were included. In first few years of the initiation of the service, most patients were referred for assessment of viability (54%) followed by assessment of etiology of cardiomyopathy (19%). However, in the subsequent years, viability referrals decreased and there was a steady increase in other indications (assessment of LV function, arrhythmias, cardiac masses, congenital heart disease,..etc.) (figure). Referral to stress MRI continued to be very low (less than 1%). 46% of the reoffered patients had an ejection fraction less than 50% and 42% of the patients had evidence of myocardial delayed enhancement.