Khaled Alfakih

Normal human left and right ventricular dimensions for MRI as assessed by turbo gradient echo and steady‐state free precession imaging sequences

To establish normal ranges of left ventricular (LV) and right ventricular (RV) dimensions as determined by the current pulse sequences in cardiac magnetic resonance imaging (MRI).

Assessment of ventricular function and mass by cardiac magnetic resonance imaging.

Cardiac magnetic resonance imaging is currently the technique of choice for precise measurements of ventricular volumes, function and left ventricular (LV) mass. The technique is 3D and hence independent of geometrical assumptions; this, along with its excellent definition of endocardial and epicardial borders, makes it highly accurate and reproducible. Cardiac magnetic resonance (CMR) is particularly useful in research, as it is highly sensitive to small changes in ejection fraction and mass, and only a small number of subjects are required for a study. The excellent reproducibility makes temporal follow-up of any individual patient in the clinical setting a realistic possibility. This review examines the merits of CMR and describes the techniques used.

New Gender-Specific Partition Values for ECG Criteria of Left Ventricular Hypertrophy Recalibration Against Cardiac MRI

ECG criteria for left ventricular hypertrophy (LVH) were mostly validated using left ventricular mass (LVM) as measured by M-mode echocardiography. LVM as measured by cardiac MRI has been demonstrated to be much more accurate and reproducible. We reevaluated the sensitivity and specificity of 4 ECG criteria of LVH against LVM as measured by cardiac MRI. Patients with systemic hypertension (n= 288) and 60 normal volunteers had their LVM measured using a 1.5-Tesla MRI system. A 12-lead ECG was recorded, and 4 ECG criteria were evaluated: Sokolow-Lyon voltage, Cornell voltage, Cornell product, and Sokolow-Lyon product. Based on a cardiac MRI normal range, 39.9% of the hypertensive males and 36.7% of the hypertensive females had elevated LVM index. At a specificity of 95%, the Sokolow-Lyon product criterion had the highest sensitivity in females (26.2%), the Cornell criterion had the highest sensitivity in males (26.2%), and the Cornell product criteria had a relatively high sensitivity in both males and females (25.0% and 23.8%). Receiver operating characteristic curves showed the Cornell and Cornell product criteria to be superior for males whereas the Sokolow-Lyon product criterion was superior for females. Comparing the mean LVM index values of the subjects who were ECG LVH positive to the normal volunteers indicated that the ECG LVH criteria detect individuals with an LVM index substantially above the normal range. We have redefined the partition values for 4 different ECG LVH criteria, according to gender, and found that they detect subjects with markedly elevated LVM index.

Left Ventricle Mass Index and the Common, Functional, X-Linked Angiotensin II Type-2 Receptor Gene Polymorphism (−1332 G/A) in Patients With Systemic Hypertension

A common intronic polymorphism, (−1332 G/A) of the angiotensin type-2 receptor gene, located on the X-chromosome, has been reported to be functional. The aim of our study was to evaluate this polymorphism for an association with left ventricular hypertrophy. Left ventricle (LV) mass was measured in 197 patients with systemic hypertension and 60 normal volunteers using a 1.5-Tesla Philips MRI system. Genotyping was performed using a restriction enzyme digestion of an initial 310-bp polymerase chain reaction product that included the angiotensin type-2 (−1332 G/A) locus. The mean LV mass index for the male patients was 94.3±19.6 g/m2 (n= 125) and for the female patients was 71.2±12.0 g/m2 (n=72). Seventy-three (37.1%) of all patients had an elevated LV mass index, defined as the mean LV mass index for normal volunteers plus 2 SD (males 77.8±9.1 g/m2, n= 30; females 61.5±7.5g/m2, n= 30). Comparison of LV mass index of the A_/AA genotype (mean LV mass index= 82.4±21.1 g/m2; n= 123) against that of the G_/GG genotype (mean LV mass index= 88.1±19.0 g/m2; n= 89) as a continuous variable was significant by ANOVA (P = 0.044). χ2 Comparison between subjects with and subjects without left ventricular hypertrophy revealed an excess of the G_/GG genotype among the group with LV hypertrophy (P = 0.031). We observed an association between the angiotensin type-2 receptor (−1332 G) allele and the presence of left ventricular hypertrophy in hypertensive subjects.

Comparison of Clinical Efficacy and Cost of a Cardiac Imaging Strategy Versus a Traditional Exercise Test Strategy for the Investigation of Patients With Suspected Stable Coronary Artery Disease

We evaluated the clinical efficacy and cost of a cardiac imaging strategy versus a traditional exercise tolerance test (ETT) strategy for the investigation of suspected stable coronary artery disease (CAD). We retrospectively collected data of consecutive patients seen in rapid access chest pain clinics at 2 UK hospitals for a period of 12 months. Hospital A investigated patients by performing ETT. Hospital B investigated patients using cardiac imaging test; 483 patients from hospital A and 295 from hospital B were included. In hospital A, 209 patients (43.3%) had contraindication to ETT. Of those who had ETT, 151 (55.1%) had negative ETT, 68 (24.8%) had equivocal ETT, and 55 (20.1%) had positive ETT, of which 53 (96.4%) had invasive coronary angiography (ICA), and of these 23 (43.4%) had obstructive CAD. In hospital B, 26 patients (8.8%) with low pretest probability had calcium score and 3 (11.5%) were positive leading to computed tomography coronary angiography; 98 patients (33.2%) with intermediate pretest probability had computed tomography coronary angiography and 5 (5.1%) were positive; 77 patients (26.1%) had stress echocardiogram and 6 (7.8%) were positive; and 57 patients (19.3%) had myocardial perfusion scintigraphy and 11 (19.3%) were positive. Hospital A performed 127 ICA (26.3% of population) and 52 (40.9%) had obstructive CAD. Hospital B performed 63 ICA (21.4% of population) and 32 (50.8%) had obstructive CAD. The average cost per patient in hospital A was £566.6 ± 490.0 (

Stress echocardiography in the age of multi-detector computed tomography

875 ± 758) and in hospital B was £487.9 ± 469.6 (

Current international guidelines for the investigation of patients with suspected coronary artery disease

750 ± 725) (p <0.001). In conclusion, our results suggest that a cardiac imaging pathway leads to fewer ICA and a higher yield of obstructive CAD at lower cost per patient.

Multi-detector computed tomography coronary angiography: the incidental lung findings

The introduction of 64-slice multi-detector computed tomography (CT) in 2005 made the non-invasive imaging of coronary arteries relatively easy to perform. Computed tomography coronary angiography (CTCA) has been shown to be highly accurate at detecting coronary artery disease (CAD), when compared with invasive X-ray coronary angiography and, in particular, has an excellent negative predictive value (NPV).1,2 There are also prognostic data confirming very low risk for patients with normal CTCA.3 One of the limitations of multidetector CT and despite very good temporal resolution of 150 ms, with half scan reconstruction, is the need for beta-Blockers to slow the heart rate to 65 bpm, for retrospective, and 60 bpm, for the low radiation dose, prospective gated acquisitions. This is to minimize coronary motion particularly of the right coronary artery. Dual-source CT, with twice the temporal resolution, can cope with faster heart rates, whereas the 320-slice CT can image the heart in one heart beat. The UK national institute of clinical excellence (NICE) have recently produced guidelines on the management of patients with chest pain of recent onset, endorsing the use of CTCA in their investigational algorithm. We discuss the radiation dose associated with …

The NICE guidelines on the assessment of chest pain

Patients suspected of having coronary artery disease (CAD) who present with new onset chest pain can be investigated by numerous diagnostic modalities. National and international guidelines have been drawn up to assist cardiologists in selecting the most appropriate investigation(s). Here, we summarize and compare three current guidelines and discuss the differences between them. The UK National Institute for Health and Care Excellence (NICE) published its guidelines in 2010.1 The guidelines recommend that patients are categorized into ‘low’ or ‘high’ risk of CAD groups, depending on whether they have a cardiovascular risk factor (diabetes, smoking, and hyperlipidaemia). Patients are assigned a pre-test probability (PTP) score of having CAD based on risk category, age, gender, and typicality of chest pain. The guidance then suggests that patients with a PTP of 400), a functional imaging test or invasive coronary angiography (ICA) is recommended. Patients with an intermediate PTP of 30–60% are recommended to have a functional imaging test; i.e. myocardial perfusion scintigraphy (MPS), stress echocardiography, or stress cardiac magnetic resonance imaging. Patients with a high PTP of 61–90% are recommended to undergo ICA, and patients with a PTP of >90% are assumed to have CAD without requiring further testing to make the diagnosis. The assessment of prognosis and management of patients diagnosed …

The α2C-Del322–325 adrenoceptor polymorphism and the occurrence of left ventricular hypertrophy in hypertensives

Multi-detector computed tomography (CT) coronary angiography (CA) has established itself, in a short space of time, as an important non-invasive tool for the diagnosis of coronary artery disease. In this editorial we discuss the incidental lung findings commonly found on CTCA. The National Institute for Health and Clinical Excellence (NICE) has recently recommended the use of CTCA as a first-line investigation in patients with stable chest pain and an estimated likelihood of coronary artery disease of 10–29%, acknowledging its excellent negative predictive value (99%).1,2 Used in this group of patients CTCA should reduce the rate of normal coronary arteries at diagnostic invasive coronary angiography, recently reported to be 39% in the American College of Cardiology National Cardiovascular Data Registry.3 Another advantage of CTCA is the fast acquisition time which should translate into low cost. A recent cost-effectiveness analysis found CTCA as an initial test or as an only test to be more cost-effective than single photon emission CT in patients who have stable chest pain without known coronary artery disease with intermediate coronary artery disease prevalence. 4 In terms of safety the radiation dose from CTCA can be as low as 2 mSv with prospective gating, where the acquisition is limited to 10% of the cardiac cycle at end-diastole, but this requires a regular rhythm below 60 bpm.5 Otherwise, retrospective gating with dose reduction techniques can keep the dose relatively low at around 10 mSv.6 Some scanners offer the potential to reduce the dose by a further 40%, with the use of a small bow tie filter, which reduces the scanning field of view (FOV), excluding the lungs.7 The benefit is not limited to dose reduction but it improves the spatial resolution and avoids the plethora of incidental lung findings, the vast majority of which are of no clinical consequence.8 Even on scanners where it is not possible to limit the scanning FOV, there is an argument to reconstruct the small FOV for the heart from the raw data and use that for reporting. The raw data are subsequently deleted. The concept of deleting the raw data is not new and is already used in CT of the spine. There are two schools of thought on the importance or otherwise of reporting the findings on the full FOV. The advocates state that these are symptomatic patients and hence the cause of their chest pain could be in the lung parenchyma or more importantly they could have an aortic dissection or a pulmonary embolus. The other incidental findings commonly quoted as important include pneumonia, interstitial lung disease, emphysema, pleural effusions, breast cancer, bronchial carcinoma and lung nodules. These alternative diagnoses may well be relevant for patients presenting to the emergency room with chest pain. However, if there is a serious concern about such a possible differential diagnosis, there is a strong argument for scanning the whole chest whereas CTCA only includes the lower half of the chest. The opposing opinion argues that the clinician, based on the patients symptoms, requested a CTCA and not a lung scan and that reporting the findings in the full FOV turns up a large number of incidentalomas, and in particular small solid lung nodules which are found in up to 69% of smokers over 50 years of age, with a very low incidence of malignancy (1.4%).9 These patients need a referral to a chest physician and further investigation with up to four additional CT scans, based on the Fleishner society recommendations, which incurs significant additional cost, a significant radiation dose and a risk associated with biopsies.8 Furthermore, at the end of a two-year period of follow-up with CT scans, new nodules will have been discovered in 20% of patients necessitating further screening. The National Lung Screening Trial completed the enrolment of 50,000 heavy smokers or ex-smokers over 55 years of age to determine whether there is benefit from screening for lung cancer and will report in three years. Until then the current recommendation from all the major societies is not to screen for lung cancer. NICE limited their recommendation for CTCA to patients presenting with stable chest pain with an estimated likelihood of coronary artery disease of 10–29%. The patients who meet these criteria are mostly young and/or women and/or have no cardiovascular risk factors. In this group of relatively well and young patients the commonest incidental lung findings are the small solid lung nodules. Even if the national lung screening trial confirms benefit from screening for lung cancer, the evidence would not apply to this low-risk group of patients. This is particularly important in the light of recent data highlighting the ever-increasing cumulative radiation dose to patients from medical imaging and particularly cardiac imaging, and the potential increase in cancer from excessive use of computed tomography.10–12 The risk of future cancer from radiation is higher in younger patients and particularly in younger women and hence it is important to keep their radiation dose from CTCA down to a minimum. This is achieved by both reducing the dose from the CTCA, through the use of dose reduction techniques, as well as the avoidance of unnecessary subsequent CT scans.