Cardiovascular magnetic resonance of acute and chronic myocardial ischaemia

BACKGROUND: Ischaemic heart disease is the leading cause of mortality and morbidity in the developed world. Cardiovascular magnetic resonance (CMR) is a non-invasive imaging modality providing in vivo myocardial tissue characterisation and quantification. We aimed to validate CMR in the field of interventional cardiology as a tool for guiding patient selection and management to the assessment of the results of interventions both in the acute and chronic settings. METHODS AND RESULTS: We investigated the impact of primary angioplasty delay on the presence and extent of myocardial salvage, microvascular obstruction and infarct size. We found that “time is muscle”, and that shorter time to reperfusion was associated with smaller infarct size (p=0.05), less microvascular obstruction (p=0.04) and a greater amount of salvaged myocardium (p=0.003). Microvascular obstruction was then used as an endpoint in a prospective randomised trial assessing the impact of a thrombectomy device as adjunctive therapy in primary PCI. The incidence and extent of microvascular damage was significantly reduced in the thrombectomy group compared to standard primary PCI (p=0.0005). CMR can identify 2 degrees of microvascular damage: early or persistent microvascular dysfunction. The latter was the strongest predictor of LV remodelling (p=0.03), it was predicted by infarct size (p=0.002), and infarct healing (shrinkage) occurred to a greater extent (p<0.006). We validated the clinical use of CMR perfusion in a cohort of patients with chronic coronary occlusion whose management is currently controversial. CMR identified myocardial viability and inducible myocardial ischaemia in a significant percentage of patients, guided revascularisation that reduced ischaemic burden (p<0.0001) with improvements in left ventricular function (p<0.0001) and health outcome measures (p<0.0001). Finally, improved CMR perfusion image quality was pursued with a new imaging protocol but this demonstrated increased incidence of artefacts (p<0.001) and lower diagnostic accuracy compared to the standard technique. CONCLUSIONS: Cardiovascular magnetic resonance provides in vivo myocardial tissue characterisation that can potentially not only guide treatment but also assess its effects. The result of this work suggests that CMR could emerge as a clinical valuable technique in numerous interventional clinical settings within acute to chronic myocardial ischaemia, in addition to providing surrogate endpoints for clinical trials

Cardiac magnetic resonance imaging unmasks presumed embolic myocardial infarction due to patent foramen ovale case report

BACKGROUND: Occurrence of paradoxical coronary embolism is reported in up to 10–15% of all myocardial infarctions but embolic infarctions presumed to be as a result of a patent foramen ovale (PFO) are rare. Although rare, it is important to identify these patients as they need appropriate investigations to confirm their diagnosis and guide further treatment. CASE SUMMARY: We present the case of a gentleman with troponin positive chest pain with non-obstructed coronaries on invasive coronary angiogram. Subsequent cardiac magnetic resonance imaging (MRI) demonstrated multi-focal myocardial infarctions in several coronary artery territories. Further investigations including echocardiogram were performed in order to identify a cause and source of the embolic infarctions and led to the diagnosis of patent foramen ovale. The patient was treated as myocardial infarction with non-obstructed coronary arteries most likely due to embolic phenomena in the presence of a PFO. CONCLUSION: Multiple focal infarctions in multiple coronary artery territories should raise the suspicion of an intra-cardiac shunt. Multi-modality imaging with cardiac MRI and echocardiogram is important in correctly identifying any source of emboli and the diagnosis of any intra-cardiac shunt. Whilst PFO closure is a possible treatment for patients, considerations regarding risk stratification and local provisions needs to be taken into account. Patients should be referred to the appropriate subspecialist to ensure suitable long-term follow-up

Diagnostic and prognostic roles of echocardiography and cardiac magnetic resonance

Cardiolog

Cardiovascular Magnetic Resonance Parametric Mapping Techniques: Clinical Applications and Limitations

Purpose of Review: Parametric mapping represents a significant innovation in cardiovascular magnetic resonance (CMR) tissue characterisation, allowing the quantification of myocardial changes based on changes on T1, T2 and T2* relaxation times and extracellular volume (ECV). Its clinical use is rapidly expanding, but it requires availability of dedicated equipment as well as expertise in image acquisition and analysis. This review focuses on the principles of CMR parametric mapping, its current clinical applications, important limitations, as well as future directions of this technique in cardiovascular medicine. Recent Findings: There is increasing evidence that CMR parametric mapping techniques provide accurate diagnostic and prognostic tools that can be applied to and support the clinical management of patients with a range of cardiovascular disease. Summary: The unique capability of CMR myocardial tissue characterisation in cardiovascular diseases has further expanded by the introduction of parametric mapping. Its use in clinical practice presents opportunities but has also limitations