Left ventricular thrombus and cerebral infarction after acute anterior myocardial infarction: a prospective positron emission tomography study

Introduction Following acute myocardial infarction, left ventricular thrombus formation predisposes to cardioembolic stroke. The diagnosis of left ventricular thrombus remains clinically challenging. We aimed to explore the true incidence of left ventricular thrombus and cerebral infarction in patients presenting with anterior ST-segment elevation myocardial infarction using non-invasive hybrid positron emission tomography (PET) and magnetic resonance imaging (MRI) of the heart and brain combined with a thrombus-specific radiotracer, fluorine-18 GP1 ([18F]GP1), which binds to the glycoprotein IIb/IIIa receptor on activated platelets. Methods In a single centre prospective observational study, patients with acute anterior ST-segment elevation myocardial infarction underwent transthoracic echocardiography (TTE), gadolinium-enhanced cardiac and brain MRI and [18F]GP1 heart and brain positron emission tomography (PET)/MRI. Heart and brain [18F]GP1 uptake were quantified using maximal target-to-background ratio (TBRmax). Results In 70 patients with acute myocardial infarction (61±8 years, 93% male, mean left ventricular ejection fraction 48±10%),the incidence of left ventricular thrombus was 3/70 (4%) by ECHO, 12/70 (17%) by cardiac MRI and 20/70 (29%) on [18F]GP1 PET (Figure 2 – panel B). [18F]GP1 uptake was associated with a lower ejection fraction, increased end diastolic volume, and persistent ST-segment elevation on the electrocardiogram (Figure 2 – panel A). An acute brain infarct was detected in 9/70 patients (13%), with only one patient having a clinically apparent stroke. Of these nine patients, 2 had evidence of left ventricular thrombus on echocardiography, 3 had evidence on cardiac MRI, and 5 had evidence of left ventricular [18F]GP1 uptake on PET (Figure 1, panel 1 and 2). The relative risk of cerebral infarction in patients who had left ventricular [18F]GP1 uptake was 3.1 (0.98-9.75, p=0.107). Conclusion In patients with recent acute anterior myocardial infarction, hybrid [18F]GP1 PET/MRI is a highly sensitive method of detecting left ventricular thrombosis and cerebral infarction, which is often clinically silent, passes undetected and is substantially underestimated. [18F]GP1 PET holds major promise for better understanding the true incidence, natural history and pathophysiology of left ventricular thrombus formation, as well as the determinants and rates of cerebral infarction after acute myocardial infarction.