Cardiovascular magnetic resonance activity in the United Kingdom: a survey on behalf of the british society of cardiovascular magnetic resonance

<p>Background: The indications, complexity and capabilities of cardiovascular magnetic resonance (CMR) have rapidly expanded. Whether actual service provision and training have developed in parallel is unknown.</p> <p>Methods: We undertook a systematic telephone and postal survey of all public hospitals on behalf of the British Society of Cardiovascular Magnetic Resonance to identify all CMR providers within the United Kingdom.</p> <p>Results: Of the 60 CMR centres identified, 88% responded to a detailed questionnaire. Services are led by cardiologists and radiologists in equal proportion, though the majority of current trainees are cardiologists. The mean number of CMR scans performed annually per centre increased by 44% over two years. This trend was consistent across centres of different scanning volumes. The commonest indication for CMR was assessment of heart failure and cardiomyopathy (39%), followed by coronary artery disease and congenital heart disease. There was striking geographical variation in CMR availability, numbers of scans performed, and distribution of trainees. Centres without on site scanning capability refer very few patients for CMR. Just over half of centres had a formal training programme, and few performed regular audit.</p> <p>Conclusion: The number of CMR scans performed in the UK has increased dramatically in just two years. Trainees are mainly located in large volume centres and enrolled in cardiology as opposed to radiology training programmes.</p&gt

Dilated Cardiomyopathy: Phosphorus 31 MR Spectroscopy at 7 T

Purpose: To test whether the increased signal-to-noise ratio of phosphorus 31 (31P) magnetic resonance (MR) spectroscopy at 7 T improves precision in cardiac metabolite quantification in patients with dilated cardiomyopathy (DCM) compared with that at 3 T. Materials and Methods: Ethical approval was obtained, and participants provided written informe consent. In a prospective study, 31P MR spectroscopy was performed at 3 T and 7 T in 25 patients with DCM. Ten healthy matched control subjects underwent 31P MR spectroscopy at 7 T. Paired Student t tests were performed to compare results between the 3-T and 7-T studies. Results: The phosphocreatine (PCr) signal-to-noise ratio increased 2.5 times at 7 T compared with that at 3 T. The PCr to adenosine triphosphate (ATP) concentration ratio (PCr/ATP) was similar at both field strengths (mean ± standard deviation, 1.48 ± 0.44 at 3 T vs 1.54 ± 0.39 at 7 T, P = .49), as expected. The Cramér-Rao lower bounds in PCr concentration (a measure of uncertainty in the measured ratio) were 45% lower at 7 T than at 3 T, reflecting the higher quality of 7-T 31P spectra. Patients with dilated cardioyopathy had a significantly lower PCr/ATP than did healthy control subjects at 7 T (1.54 ± 0.39 vs 1.95 ± 0.25, P = .005), which is consistent with previous findings. Conclusion: 7-T cardiac 31P MR spectroscopy is feasible in patients with DCM and gives higher signal-to-noise ratios and more precise quantification of the PCr/ATP than that at 3 T. PCr/ATP was significantly lower in patients with DCM than in control subjects at 7 T, which is consistent with previous findings at lower field strengths

"Lone" Atrial Fibrillation Is Associated With Impaired Left Ventricular Energetics That Persist Despite Successful Catheter Ablation.

BACKGROUND: -"Lone" atrial fibrillation (AF) may reflect a subclinical cardiomyopathy that persists after sinus rhythm (SR) restoration, providing a substrate for AF recurrence. To test this hypothesis, we investigated the effect of restoring SR by catheter ablation on left ventricular (LV) function and energetics in patients with AF but no significant comorbidities. METHODS: -Fifty-three patients with symptomatic paroxysmal or persistent AF and without significant valvular disease, uncontrolled hypertension, coronary artery disease, uncontrolled thyroid disease, systemic inflammatory disease, or diabetes (i.e. "lone" AF) undergoing ablation and 25 matched controls in SR were investigated. Magnetic resonance imaging quantified LV ejection fraction (LVEF), peak systolic circumferential strain (PSCS), and left atrial volumes and function, while Phosphorus-31 MR spectroscopy evaluated ventricular energetics (ratio of phosphocreatine-to-adenosine triphosphate [PCr/ATP]). AF burden was determined pre- and post-ablation by 7-day Holter monitoring; intermittent ECG event monitoring was also undertaken after ablation to investigate for asymptomatic AF recurrence. RESULTS: -Before ablation, LV function and energetics were both significantly impaired in patients compared to controls (respectively: LVEF 61% [IQR 52-65%] versus 71% [IQR 69-73%], p<0.001; PSCS -15% [IQR -11 to -18%] versus -18% [-17 to -19%], p=0.002; PCr/ATP 1.81±0.35 versus 2.05±0.29, p=0.004). As expected, patients also had dilated and impaired left atria compared to controls (all p<0.001). Early after ablation (1 to 4 days), LVEF and PSCS improved in patients recovering SR from AF (respectively: LVEF +7.0±10%, p=0.005; PSCS -3.5±4.3%, p=0.001) but were unchanged in those in SR during both assessments (both p=ns). At 6-9 months post-ablation, AF burden reduced significantly (from 54% [IQR 1.5%-100%] to 0% [IQR 0%-0.1%], p<0.001). However, LVEF and PSCS did not improve further (both p=ns) and remained lower than in controls (p<0.001 and p=0.003, respectively). Similarly, there was no significant improvement in atrial function from pre-ablation (p=ns), and this also remained lower than in controls (p<0.001). PCr/ATP was unaffected by heart rhythm during assessment and AF burden before ablation (both p=ns). It was unchanged post-ablation (p=0.57), remaining lower than in controls irrespective of both recovery of SR and freedom from recurrent AF (p=0.006 and p=0.002, respectively). CONCLUSIONS: -"Lone" AF patients have impaired myocardial energetics and subtle LV dysfunction, which do not normalise after ablation. These findings suggest that AF may be the consequence (rather than the cause) of an occult cardiomyopathy, which persists despite a significant reduction in AF burden following ablation