Reducing transfer times for coronary angiography in patients with acute coronary syndromes: one solution to a national problem.

BACKGROUND: Patients with acute coronary syndrome (ACS) are at high risk of further cardiac events and benefit from early intervention, as reflected by international guidelines recommending early transfer to interventional centres. The current average waiting time of up to 21 days contravenes evidence based early intervention, creates geographical inequity of access, wastes bed days, and is unsatisfactory for patients. METHODS: A regional transfer unit (RTU) was created to expatriate access of ACS patients referred from other centres to the revascularisation service. By redesigning the care pathway patients arriving on the RTU undergo angiography within 24 hours, and then leave the RTU the following day, allowing other ACS patients to be treated. RESULTS: During the first six months of the RTU, the mean waiting time from referral to procedure decreased from 20 (SD 15) days (range 0-51) to 8 (SD 3) days (range 0-21) for 365 patients transferred from a district general hospital. Ninety seven per cent of patients underwent angiography within 24 hours, 61% having undergone percutaneous coronary intervention at the same sitting, and 78% were discharged home within 24 hours. CONCLUSIONS: Delivering standards laid out in the National Service Framework, reducing inequalities of care across the region, and facilitating evidence based strategies of care represents a challenging and complex issue. For high risk patients suffering ACS who need early invasive investigation, a coordinated network wide approach together with the creation of an RTU resulted in a 62% reduction in waiting times for no extra resources. Further improvements can be expected through increased capacity of this verified strategy.

Infarct zone viability influences ventricular remodelling after late recanalisation of an occluded infarct related artery.

OBJECTIVE: To investigate the influence of infarct zone viability on remodelling after late recanalisation of an occluded infarct related artery. METHODS: A subgroup of 26 volunteers from TOAT (the open artery trial) underwent dobutamine stress cardiovascular magnetic resonance at baseline to assess the amount of viable myocardium present with follow up to assess remodelling at one year. TOAT studied patients with left ventricular dysfunction after anterior myocardial infarction (MI) associated with isolated proximal occlusion of the left anterior descending coronary artery with randomisation to percutaneous coronary intervention (PCI) with stent at 3.6 weeks after MI (PCI group) or to medical treatment alone (medical group). RESULTS: In the PCI group there was a significant relation between the number of viable segments within the infarct zone and improvement in end systolic volume index (-7.7 ml/m2, p = 0.02) and increased ejection fraction (4.1%, p = 0.03). The relation between viability and improvements in end diastolic volume index (-8.8 ml/m2, p = 0.08) and mass index (-6.3 g/m2, p = 0.01) did not reach significance (p = 0.27 and p = 0.8, respectively). In the medical group, there was no significant relation between the number of viable segments in the infarct zone and the subsequent changes in end diastolic (p = 0.84) and end systolic volume indices (p = 0.34), ejection fraction (p = 0.1), and mass index (p = 0.24). CONCLUSION: The extent of viable myocardium in the infarct zone is related to improvements in left ventricular remodelling in patients who undergo late recanalisation of an occluded infarct related artery.

Effects of carvedilol on left ventricular remodelling in chronic stable heart failure: a cardiovascular magnetic resonance study.

BACKGROUND: The ability of beta blockers to improve left ventricular function has been demonstrated, but data on the effects on cardiac remodelling are limited. OBJECTIVE: To investigate, using cardiovascular magnetic resonance (CMR), the effects of carvedilol on left ventricular remodelling in patients with chronic stable heart failure and left ventricular systolic dysfunction caused by coronary artery disease. DESIGN: Randomised, double blind, placebo controlled study. SETTING: Chronic stable heart failure. PATIENTS AND INTERVENTION: 34 patients with chronic stable heart failure and left ventricular systolic function taking part in the CHRISTMAS trial (double blind carvedilol v placebo) underwent CMR before randomisation and after six months of treatment. MAIN OUTCOME MEASURE: Left ventricular remodelling at six months. RESULTS: The carvedilol and placebo groups were well balanced at baseline, with no significant intergroup differences. Over the study period, there was a significant reduction in end systolic volume index (ESV(I)) and end diastolic volume index (EDV(I)) between the carvedilol and the placebo group (carvedilol -9 v placebo +3 ml/m2, p = 0.0004; carvedilol -8 v placebo 0 ml/m2, p = 0.05). The ejection fraction increased significantly between the groups (carvedilol +3% v placebo -2%, p = 0.003). CONCLUSIONS: Treatment of chronic stable heart failure with carvedilol results in significant improvement in left ventricular volumes and function. These effects might contribute to the benefits of carvedilol on mortality and morbidity in patients with chronic heart failure.

Improved cine cardiovascular magnetic resonance using Clariscan (NC100150 injection).

We evaluated the use of Clariscan 0.75, 2, and 5 mg Fe/kg body weight in six patients to determine optimal dosing for short repetition time cine imaging. Breathhold cine images were acquired in the vertical and horizontal long axes and the short axis. Blood-pool signal-to-noise ratio increased significantly in all planes (p < 0.01) but was least marked in the short axis. Myocardial signal-to-noise ratio increased by a lesser amount (p < 0.05). Myocardial to blood-pool signal-difference-to-noise ratio improved significantly in the long axes (p < 0.05) and was greatest at 2 mg Fe/kg body weight, but changes in the short axis were minor. With the 5-mg Fe/kg body weight dose, the response was reduced or reversed due to T2* effects. Visual assessment improved in all planes (p < 0.05) and was optimal at 2 mg Fe/kg body weight. In conclusion, Clariscan improves short repetition time cardiac breathhold cine imaging, particularly in the long axis planes, with an optimal dose of 2 mg Fe/kg body weight.

The role of cardiovascular magnetic resonance in heart failure.

Cardiovascular Magnetic Resonance (CMR) is an accepted gold standard for non-invasive, accurate, and reproducible assessment of cardiac mass and function. The interest in its use for viability, myocardial perfusion and coronary artery imaging is also widespread and growing rapidly as the hardware and expertise becomes available in more centres, and the scans themselves become more cost effective. In patients with heart failure, accurate and reproducible serial assessment of remodelling is of prognostic importance and the lack of exposure to ionizing radiation is helpful. The concept of an integrated approach to heart failure and its complications using CMR is fast becoming a reality, and this will be tested widely in the coming few years, with the new generation of dedicated CMR scanners.

Comparison of left ventricular ejection fraction and volumes in heart failure by echocardiography, radionuclide ventriculography and cardiovascular magnetic resonance; are they interchangeable?

AIMS: To prospectively compare the agreement of left ventricular volumes and ejection fraction by M-mode echocardiography (echo), 2D echo, radionuclide ventriculography and cardiovascular magnetic resonance performed in patients with chronic stable heart failure. It is important to know whether the results of each technique are interchangable, and thereby how the results of large studies in heart failure utilizing one technique can be applied using another. Some studies have compared cardiovascular magnetic resonance with echo or radionuclude ventriculography but few contain patients with heart failure and none have compared these techniques with the current fast breath-hold acquisition cardiovascular magnetic resonance. METHODS AND RESULTS: Fifty two patients with chronic stable heart failure taking part in the CHRISTMAS Study, underwent M-mode echo, 2D echo, radionuclude ventriculography and cardiovascular magnetic resonance within 4 weeks. The scans were analysed independently in blinded fashion by a single investigator at three core laboratories. Of the echocardiograms, 86% had sufficient image quality to obtain left ventricular ejection fraction by M-mode method, but only 69% by 2D Simpson's biplane analysis. All 52 patients tolerated the radionuclude ventriculography and cardiovascular magnetic resonance, and all these scans were analysable. The mean left ventricular ejection fraction by M-mode cube method was 39+/-16% and 29+/-15% by Teichholz M-mode method. The mean left ventricular ejection fraction by 2D echo Simpson's biplane was 31+/-10%, by radionuclude ventriculography was 24+/-9% and by cardiovascular magnetic resonance was 30+/-11. All the mean left ventricular ejection fractions by each technique were significantly different from all other techniques (P<0.001), except for cardiovascular magnetic resonance ejection fraction and 2D echo ejection fraction by Simpson's rule (P=0.23). The Bland-Altman limits of agreement encompassing four standard deviations was widest for both cardiovascular magnetic resonance vs cube M-mode echo and cardiovascular magnetic resonance vs Teichholz M-mode echo at 66% each, and was 58% for radionuclude ventriculography vs cube M-mode echo, 44% for cardiovascular magnetic resonance vs Simpson's 2D echo, 39% for radionuclide ventriculography vs Simpson's 2D echo, and smallest at 31% for cardiovascular magnetic resonance-radionuclide ventriculography. Similarly, the end-diastolic volume and end-systolic volume by 2D echo and cardiovascular magnetic resonance revealed wide limits of agreement (52 ml to 216 ml and 11 ml to 188 ml, respectively). CONCLUSION: These results suggest that ejection fraction measurements by various techniques are not interchangeable. The conclusions and recommendations of research studies in heart failure should therefore be interpreted in the context of locally available techniques. In addition, there are very wide variances in volumes and ejection fraction between techniques, which are most marked in comparisons using echocardiography. This suggests that cardiovascular magnetic resonance is the preferred technique for volume and ejection fraction estimation in heart failure patients, because of its 3D approach for non-symmetric ventricles and superior image quality.

Quantification of right and left ventricular function by cardiovascular magnetic resonance.

Cardiac dysfunction is a major cause of cardiovascular morbidity and mortality. Accurate and reproducible assessment of cardiac function is essential for the diagnosis, the assessment of prognosis and evaluation of a patient's response to therapy. Cardiovascular Magnetic Resonance (CMR) provides a measure of global and regional function that is not only accurate and reproducible but is noninvasive, free of ionising radiation, and independent of the geometric assumptions and acoustic windows that limit echocardiography. With the advent of faster scanners, automated analysis, increasing availability and reducing costs, CMR is fast becoming a clinically tenable reference standard for the measurement of cardiac function.

Left ventricular function and mass after orthotopic heart transplantation: a comparison of cardiovascular magnetic resonance with echocardiography.

OBJECTIVE: We compared the assessment of left ventricular function and mass by M-mode echocardiography (echo) with fast breath-hold cardiovascular magnetic resonance (CMR) in patients who received orthotopic heart transplantation. We also sought to establish the reproducibility of breath-hold CMR in this patient population. METHODS: We prospectively acquired 51 sets of echo and CMR data in 21 patients who had undergone orthotopic heart transplantation. We examined the intraobserver and interobserver reproducibility of breath-hold CMR in this group and compared it with published data. We compared the left ventricular ejection fraction (EF) and mass determined by echo with the CMR data. RESULTS: The average time between CMR and echo was 0 +/- 7 days (mean +/- SD), the time between each set of CMR-echo data acquisition was 5.1 +/- 4.1 months. Cardiovascular magnetic resonance showed good reproducibility in this population, with intraobserver percentage variability of 2.2% +/- 2.4% for EF and 3. 2% +/- 2.7% for mass, and interobserver percentage variability of 2. 4% +/- 1.9% for EF and 2.2% +/- 1.9% for mass. The Bland-Altman limits of agreement between echo and CMR were wide for both EF (-9. 6% to 15%) and mass, irrespective of the formula used (-61.3 to 198 g for the Bennett and Evans formula, -65.4 to 196.8 g for the American Society of Echocardiography (ASE) formula, -65.3 to 181 g for the Devereux formula, and -95.2 to 64.6 g for the Teichholz formula). CONCLUSION: Fast-acquisition CMR is reproducible in recipients of transplanted hearts. We found poor agreement with the results of echo. The choice of technique will depend on local resources as well as the clinical importance of the result. Echo remains readily available and gives rapid assessment of volumes, EF, and mass. However, the good reproducibility of CMR may make it a more suitable technique for long-term follow-up of an individual or of a study population.

Left ventricular quantification in heart failure by cardiovascular MR using prospective respiratory navigator gating: comparison with breath-hold acquisition.

Cardiovascular magnetic resonance (CMR) is the reference standard for the assessment of cardiac function. Faster sequences, such as breath-hold (BH) fast low-angle shot, have made CMR more clinically acceptable and cost effective. In a significantly large patient group, however, holding their breath is difficult, resulting in poor-quality images. We compared prospective navigator-echo respiratory gating (NE), which allows image acquisition during free breathing, and BH imaging in 14 patients with heart failure and 10 normal volunteers. There was good agreement between both NE and BH volumes, mass, and ejection fraction. The image quality of both NE basal and apical slices was significantly better than the corresponding BH slices in both the heart failure (P < 0.01) and normal groups (P < 0.05). The NE image acquisition was more time efficient than the BH acquisition in the heart failure group (P < 0. 01), with no difference in the normal group (P = 0.2). Thus, prospective navigator-echo gating, previously only described in coronary artery imaging, can be used in the assessment of cardiac function. It is particularly useful in patients who find it difficult to hold their breath in whom NE provides good-quality, time-efficient images.

Establishment and performance of a magnetic resonance cardiac function clinic.

Our objective was to establish a cardiovascular magnetic resonance (CMR) cardiac function clinic to provide an assessment of cardiac volume, mass, and function in patients with heart failure on the same day as their cardiology outpatient clinic appointment. Sixty-four patients attended the CMR function clinic. The reproducibility, patient acceptability, and time efficiency of the CMR clinic were assessed and compared with radionuclide ventriculography (RNV) and echocardiography (echo). Reports were available in the cardiology outpatient clinic within 2 hr of the CMR appointment time. The reproducibility of volumes, ejection fraction, and mass in this heart failure population was good and comparable with CMR studies in the normal population. CMR was more acceptable to the patients than both RNV and echo (p < 0.05). The total time for CMR was less than that of RNV (42 +/- 4 and 61 +/- 4 min, respectively; p < 0.001) but more than that of echo (echo, 23 +/- 2 min; p < 0.001). Comparison of ejection fractions revealed a correlation between CMR and RNV of 0.7, but Bland-Altman limits of agreement were wide (-10.5% to 18.9%). For CMR versus echo, the correlation was 0.6, and the limits of agreement were wider (-29.9% to 23.3%). The correlation between RNV and echo was 0.2 with wider limits of agreement (-29.8% to 24. 9%). In conclusion, CMR can provide a rapid, reproducible, and patient acceptable assessment of cardiac function in heart failure patients, whereas other methods appear to have a wider variance. The high reproducibility of CMR lends itself to the follow-up of clinical progression and the effect of treatment in patients with heart failure.

Reduction in sample size for studies of remodeling in heart failure by the use of cardiovascular magnetic resonance.

Fast breathhold cardiovascular magnetic resonance (CMR) has become a reference standard for the measurement of cardiac volumes, function, and mass. The implications of this for sample sizes for remodeling studies in heart failure (HF) have not been elucidated. We determined the reproducibility of CMR in HF and calculated the sample size requirements and compared them with published values for echocardiography. Breathhold gradient echo cines of the left ventricle were acquired in 20 patients with HF and 20 normal subjects. Sample size values were calculated from the interstudy standard deviation of the difference. The percentage variability of the measured parameters in our HF group of intraobserver (2.0-7.4%), interobserver (3.3-7.7%), and interstudy (2.5-4.8%) measurements was slightly larger than for our normal group (1.6-6.6%, 1.6-7.3%, and 2.0-7.3%, respectively) but remained comparable with previous studies in normal subjects. The calculated sample sizes in patients with HF for CMR to detect a 10-ml change in end-diastolic volume (n = 12) and end-systolic volume (n = 10), a 3% change in ejection fraction (n = 15), and a 10-g change in mass was (n = 9) were substantially smaller than recently published values for two-dimensional echocardiography (reduction of 81-97%). Breathhold CMR is a fast comprehensive technique for the assessment of cardiac volumes, function, and mass in HF that is accurate but also highly reproducible. This allows a considerable reduction in the patient numbers required to prove a hypothesis in research studies, which suggests a potential for important research cost savings.