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BackgroundCardiac Magnetic Resonance (CMR) is increasingly being used for diagnosing various cardiac conditions. Parametric mapping enables quantitative myocardial characterization by directly measuring myocardial T1 and T2 values. However, reference values of parametric mapping are not standardized across different vendors and scanners, causing drawbacks for clinical implementation of this technique across different sites. We assessed the reference ranges of native T1 and T2 values in a healthy Maltese cohort to establish a local parametric mapping service. Methods and ResultsHealthy subjects (n=51; mean age 36.0 [range 19-59] years) with normal cardiac function on CMR were recruited. Subjects underwent uniform parametric mapping pulse sequences (MOLLI 5(3)3 for native T1 mapping, and gradient echo single shot FLASH readout for T2 mapping) on a 3T Siemens MAGNETOM Vida scanner. Native T1 and T2 values were measured by placing a region of interest within the interventricular septum at midventricular level. Intra-and inter-observer variability were assessed using Bland-Altman plots. Normal distribution of data was assessed using Kolmogorov-Smirnov test (p-value of 0.773 for native T1, p-value of 0.125 for T2). Mean ±1.96 SD was used as a reference range. Mean native T1 and T2 values were 1200.1 ±30.7 ms and 39.5 ±1.8 ms, respectively. All parameters had excellent dayto-day intra-observer reproducibility and inter-observer reproducibility. ConclusionFor the rst time in Malta, we established the native T1 and T2 parametric mapping reference values for healthy Caucasian Maltese individuals. This will assist cardiologists to establish diagnosis, disease progression, and response to treatment of various myocardial diseases locally.

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ObjectivesThe aims of this study were to evaluate the inconsistency of aortic stenosis (AS) severity between CT aortic valve area (CT-AVA) and echocardiographic Doppler parameters, and to investigate potential underlying mechanisms using computational fluid dynamics (CFD).MethodsA total of 450 consecutive eligible patients undergoing transcatheter AV implantation assessment underwent CT cardiac angiography (CTCA) following echocardiography. CT-AVA derived by direct planimetry and echocardiographic parameters were used to assess severity. CFD simulation was performed in 46 CTCA cases to evaluate velocity profiles.ResultsA CT-AVA>1 cm2 was present in 23% of patients with echocardiographic peak velocity≥4 m/s (r=−0.33) and in 15% patients with mean Doppler gradient≥40 mm Hg (r=−0.39). Patients with inconsistent severity grading between CT and echocardiography had higher stroke volume index (43 vs 38 mL/m2, p<0.003) and left ventricular outflow tract (LVOT) flow rate (235 vs 192 cm3/s, p<0.001). CFD simulation revealed high flow, either in isolation (p=0.01), or when associated with a skewed velocity profile (p=0.007), as the main cause for inconsistency between CT and echocardiography.ConclusionSevere AS by Doppler criteria may be associated with a CT-AVA>1 cm2 in up to a quarter of patients. CFD demonstrates that haemodynamic severity may be exaggerated on Doppler analysis due to high LVOT flow rates, with or without skewed velocity profiles, across the valve orifice. These factors should be considered before making a firm diagnosis of severe AS and evaluation with CT can be helpful.

ObjectiveA proportion of patients with suspected ST-elevation myocardial infarction (STEMI) presenting for primary percutaneous coronary intervention (PPCI) do not have obstructive coronary disease and other conditions may be responsible for their symptoms and ECG changes. In this study, we set out to determine the prevalence and aetiology of alternative diagnoses in a large PPCI cohort as determined with multimodality imaging and their outcome.MethodsFrom 2009 to 2012, 5238 patients with suspected STEMI were referred for consideration of PPCI. Patients who underwent angiography but had no culprit artery for revascularisation and no previous history of coronary artery disease were included in the study. Troponin values, imaging findings and all-cause mortality were obtained from hospital and national databases.ResultsA total of 575 (13.0%) patients with a mean age of 58±15 years (69% men) fulfilled the inclusion criteria. A specific diagnosis based on imaging was made in 237 patients (41.2%) including cardiomyopathies (n=104, 18%), myopericarditis (n=48, 8.4%), myocardial infarction/other coronary abnormality (n=27, 4.9%) and severe valve disease (n=23, 4%). Pulmonary embolism and type A aortic dissection were identified in seven (1.2%) and four (0.7%) cases respectively. A total of 40 (7.0%) patients died over a mean follow-up of 42.6 months.ConclusionsA variety of cardiac and non-cardiac conditions are prevalent in patients presenting with suspected STEMI but culprit-free angiogram, some of which may have adverse outcomes. Further imaging of such patients could thus be useful to help in appropriate management and follow-up.