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In the majority of patients with left ventricular (LV) dysfunction, this condition results from ischaemic cardiomyopathy that is caused by coronary artery disease and subsequent ischaemia and myocardial infarction. However, normal coronary arteries are found in a substantial proportion of patients with LV dysfunction. While a patient is inevitably exposed to a small but considerable risk when performing a coronary angiogram, research has focused on seeking non-invasive methods to differentiate ischaemic from non-ischaemic cardiomyopathy (NICM), which requires an importantly different therapeutic approach than in the case of ischaemic cardiomyopathy. Moreover, NICM has a heterogeneous aetiology resulting from a complex interplay between predisposed genetic constitution and the detrimental effects of infectious and/or toxic agents on the function of myocardium. Consequently, further optimisation of treatment in NICM patients warrants determination of the underlying cause(s) of NICM.
In the last decade, important progress has been made in determining the aetiology of cardiomyopathies by using cardiac magnetic resonance imaging (CMR). CMR allows a comprehensive, non-invasive assessment of cardiac function, morphology and tissue characterisation within a 45 min timeframe.
Since an introduction to CMR techniques has recently been published in this series, we will restrict the description of CMR techniques to a brief summary of their role in tissue differentiation and determination of the aetiology of cardiomyopathies (table 1).
Although a classification based on genetic interrogation of cardiomyopathies has been advocated, we will classify NICM according to the World Health Organization into hypertrophic cardiomyopathy (HCM), restrictive cardiomyopathy (RCM), dilated cardiomyopathy (DCM), arrhythmogenic right ventricular cardiomyopathy (ARVC) and unclassified cardiomyopathy, in order to concur with clinical practice.
Differentiating physiological from pathological hypertrophy
LV hypertrophy is diagnosed when LV mass exceeds the normal range, which is 85–181 g or 46–83 g/m2 for males and 66–114 g or 37–67 g/m2 for females with steady state free precession (SSFP) cine imaging. …