Intravascular ultrasound and virtual histology interpretation of plaque rupture and thrombus in acute coronary syndromes

Evading the fate of Pheidippides: acute coronary thrombosis in a young marathon runner with minimal atherosclerosis but sickle cell trait

Marathon running transiently increases the risk of sudden cardiac death. Some previous studies have suggested that this is due to relatively advanced but asymptomatic atherosclerosis. Other theories suggest that potentiation of inflammation and the coagulation cascade, by extremes of exertion, is more important. We present a clinical case of a young, previously fit athlete who felt chest discomfort eight miles into a marathon but finished the race. Shortly after completion he felt very unwell and had chest pain. Ambulance electrocardiograms showed evidence of an evolving anterior myocardial infarction. Invasive assessment with coronary angiography and intravascular ultrasound was able to show the mechanism of thrombosis. Fissuring of a small rim of atherosclerosis potentiated a large pro-thrombotic response, the patient was also found to have sickle cell trait. Medical treatment with blood thinning drugs was able to restore normality to the vessel over a period of two weeks, without the need for angioplasty or stent implantation.

Construction and validation of a plaque discrimination score from the anatomical and histological differences in coronary atherosclerosis: the Liverpool IVUS-V-HEART (Intra Vascular UltraSound-Virtual-Histology Evaluation of Atherosclerosis Requiring Treatment) study

AIMS

New markers to help stratify coronary atherosclerosis are needed. Although attempts have been made to differentiate active lesions from those that are stable, none of these has ever been formalised into a discriminatory score. The aim of this study was to analyse the differences between culprit ACS lesions and culprit stable angina lesions with intravascular ultrasound-derived virtual histology and to construct and validate a plaque score.

METHODS AND RESULTS

Prior to percutaneous coronary intervention (PCI), we performed volumetric, intravascular ultrasound-derived virtual histology (IVUS-VH) analysis in acute coronary syndrome (ACS) culprit lesions (AC - n=70) and stable angina culprit lesions (SC - n=35). A direct statistical comparison of IVUS-VH data and multiple logistic regression analysis was undertaken. Four main factors were found to be associated (p<0.05) with an AC lesion phenotype: necrotic core/dense calcium (NC/DC) ratio; minimum lumen area <4 mm2 (MLA <4); remodelling index @MLA >1.05 and VH-TCFA presence. Calculation of each logistic regression coefficient and the equation produces an active plaque discrimination score with an AUC of 0.96 on receiver operating characteristics (ROC) analysis. Validation of the score in 50 independent plaques from the Thoraxcenter in Rotterdam revealed an AUC of 0.71, confirming continued diagnostic ability.

CONCLUSIONS

We have found four features on IVUS and VH that can predict and discriminate ACS culprit lesion phenotypes from those that are clinically stable. Subsequently, we have constructed and validated the Liverpool Active Plaque Score based upon these features. It is hoped this score may help diagnose active coronary plaques, in the future, to help prevent major adverse cardiac events.

Double jeopardy: multi-modality imaging of monozygotic "twin cap" atherosclerosis

The investigation of asymptomatic but potentially vulnerable atherosclerosis is not yet a major focus for clinical Cardiologists. We have illustrated the contemporary investigation and treatment of such disease using a clinical case that involved monozygotic twins. One twin (T1) had unfortunately suffered a cardiac arrest whilst jogging and survived only due to bystander CPR and prompt defibrillation. His identical twin brother (T2), on subsequent investigation, harbours a compositionally identical lesion in a proximal coronary vessel that has not yet ruptured or provoked a clinical event. Following the presentation of both non-invasive and invasive images, we discuss the need for active suspicion and intensive treatment for those people with a 'genetic' risk of future myocardial infarction.