Treatment of myocardial ischaemia-reperfusion injury in patients with ST-segment elevation myocardial infarction: promise, disappointment, and hope.

Acute myocardial infarction (AMI) is a major cause of morbidity and mortality worldwide. Timely reperfusion with primary percutaneous coronary intervention (PPCI) remains the gold standard in patients presenting with ST-segment elevation myocardial infarction (STEMI), limiting infarct size, preserving left ventricular ejection fraction (LVEF), and improving clinical outcomes. Despite this, a significant proportion of STEMI patients develop post-infarct heart failure. We review the current understanding and up-to-date evidence base for therapeutic intervention of ischaemia-reperfusion injury (IRI), a combination of myocardial ischaemia secondary to acute coronary occlusion and reperfusion injury leading to further myocardial injury and cell death. Multiple treatment modalities have been shown to be cardioprotective and reduce IRI in experimental animal models. Recent phase II/III randomised controlled trials (RCT) have assessed multiple cardioprotective strategies ranging from ischaemic conditioning, therapeutic hypothermia and hyperoxaemia to pharmacological therapies. While several therapies have been shown to reduce infarct size in animal models or proof-of-concept studies, many larger scale trial results have proven inconsistent and disappointing. Hard clinical outcomes remain elusive. We discuss potential reasons for the difficulties in translation to clinical practice.

Patient, Clinician, and Healthcare Perspectives in Evaluating Care Pathways for Stable Chest Pain.

Chest pain is one of the most common reasons for patients to present to healthcare professionals. One of the main challenges with the management of chest pain is the wide differential diagnosis, ranging from minor chest trauma to potentially life-threatening acute myocardial infarction. In a patient-centered health service pathway, the aim is to assess, investigate, diagnose, and treat patients in the safest and most accurate, time, and cost-efficient manner. This report describes the concept of clinical pathways and their importance. It iterates different perspectives of the investigation of chest pain and the barriers to understanding the clinical sequence of events. By considering the patient, clinician, and healthcare service perspective, it is possible to critically evaluate the current stable chest pain pathway. This exercise gives consideration into the way in which patient care could be improved.

The relationship between the contralateral collateral supply and myocardial viability on cardiovascular magnetic resonance: can the angiogram predict functional recovery?

BACKGROUND: A collateral circulation which supplies a myocardial territory, subtended by a chronic total occlusion (CTO), may be observed at invasive coronary angiography. The prognostic and protective role of such collateralisation is well demonstrated suggesting that a good collateral circulation may be a predictor of myocardial viability, but current evidence is discrepant. The aim of this study is to assess the relationship between collateralisation from the contralateral epicardial vessels and myocardial viability by cardiovascular magnetic resonance (CMR). METHOD: Consecutive patients with CTO having had both CMR and invasive coronary angiography were retrospectively identified. The collateral circulation was graded with the Cohen and Rentrop classification. CMR images were graded per segment for wall motion (1: normal/hyperkinetic, 2: hypokinetic, 3: akinetic, or 4: dyskinetic) and wall motion score index (WMSI) was calculated. The segmental transmurality of late gadolinium enhancement was scored as 1 (0%), 2 (1-25%), 3 (26-50%), 4 (51-75%) and 5 (76-100%). RESULTS: A good collateral circulation was more likely to supply viable myocardium (p=0.01). There was no relationship between collateral circulation supply and wall motion score index (WMSI), however, increasing transmurality of LGE was significantly associated with higher mean WMSI representing increasing dysfunctional myocardium (p<0.001). CONCLUSION: The presence of collateral coronary circulation at angiography predicts the presence of viability on cardiovascular MRI, with a gradation of greater viability associated with improving Rentrop grade. A collateral circulation at angiography should, therefore, prompt more formal assessment of viability and consideration of revascularisation in order for the patient to obtain the associated functional and prognostic improvement.

Cardiac imaging to investigate suspected cardiac pain in the post-treadmill era.

Symptomatic cardiovascular disease is one of the leading causes of hospital admissions in the UK; along with emergency attendances, over 100,000 patients are investigated using treadmill testing via rapid access chest pain clinics each year. With the introduction of new technologies, clinicians have a wide choice of investigations including nuclear perfusion scanning, dobutamine stress echocardiography, cardiac computed tomography and stress cardiac magnetic resonance imaging. These imaging modalities have their strengths and weaknesses, which depend not only on the pre-test likelihood of significant coronary artery disease but also the clinical characteristics of the patient. This article will review the differing imaging modalities, the patient experience, accuracy, prognostic data and future prospects for cardiac computed tomography and magnetic resonance imaging.

Safety and feasibility of dobutamine stress cardiac magnetic resonance for cardiovascular assessment prior to renal transplantation.

AIMS: Current guidelines recommend cardiovascular risk assessment prior to renal transplantation. There is currently no evidence for the role of cardiovascular magnetic resonance (CMR) in this population, despite an established evidence base in the non-chronic kidney disease (CKD) population. Our aim is to determine the feasibility and safety of dobutamine stress CMR (DSCMR) imaging in the risk stratification of CKD patients awaiting renal transplantation. METHODS: CKD patients who were deemed at high risk for coronary artery disease (CAD) and awaiting renal transplantation underwent DSCMR. RESULTS: Forty-one patients whose median age was 56 years (range 28­73 years) underwent DSCMR. Nineteen were undergoing haemodialysis, 10 peritoneal dialysis and 12 pre-dialysis. The aetiology of the renal failure was diabetes mellitus in 29%, glomerulonephritis in 24%, hypertension in 22% and autosomal dominant polycystic kidney disease in 10%. Thirty-eight patients (93%) achieved the end point, either positive for ischaemia or negative, achieving at least 85% of age-predicted heart rate. Two of them did not achieve target heart rate and one was discontinued because of severe headache. Of the 38 patients who achieved the end point, 35 (92%) were negative for inducible wall motion abnormalities and four (10%) were positive. There were no serious adverse effects. CONCLUSION: DSCMR is a well tolerated and viable investigation for the cardiovascular risk stratification of high-risk CKD patients prior to renal transplantation. DSCMR already has an established evidence base in the non-CKD population with superiority over other noninvasive techniques. Larger studies with outcome data are now required to define its true utility in the CKD population.

Multimodality imaging in bland-White-Garland syndrome in an adult with a left dominant coronary artery system.

Bland-White-Garland syndrome, also known as anomalous origin of the left coronary artery from the pulmonary artery, is a rare congenital disorder affecting around one in 300,000 live births. The majority of these present within the first year of life with 90% mortality rate if untreated and consequently is an extremely rare presentation in the adult. We present the first published case with a left dominant system in an adult presenting in their late 20s, illustrated by multimodality imaging.

Late percutaneous coronary intervention for an occluded infarct-related artery in patients with preserved infarct zone viability: a pooled analysis of cardiovascular magnetic resonance studies.

BACKGROUND: The results of clinical trials assessing the effect of late opening of infarct-related artery (IRA) on left ventricular ejection fraction (LVEF) and size in stable patients are equivocal, which may be related to the fact that the presence of viability was not a requirement for randomization in these trials. The aim of the study was to assess the influence of late percutaneous coronary intervention (PCI) with optimal medical therapy (OMT) vs. OMT alone on cardiac function and remodeling in patients presenting infarct zone with preserved viability on cardiovascular magnetic resonance (CMR). METHODS: The analysis included pooled data of 43 patients from 3 randomized studies. All patients underwent CMR before randomization, but only in 1 previously unpublished study was preserved viability required for randomization to treatment. Follow-up CMR was performed after 6-12 months. RESULTS: Late PCI with OMT led to improved LVEF (+5 ± 7% vs. -1 ± 6%, p = 0.005), decreased left ventricular end-systolic volume (-11 ± 19 mL vs. 12 ± 40 mL, p = 0.02) and a trend towards a decrease in end-diastolic volume (-7 ± 27 mL vs. 15 ± 47 mL, p = 0.07) in comparison to OMT alone. Increased LVEF and decreased left ventricular volumes were observed after the analysis was restricted to patients with left anterior descending artery (LAD) occlusion. CONCLUSIONS: In patients with the presence of infarct zone viability, OMT with late PCI for an occluded IRA (particularly LAD) is associated with improvement of left ventricular systolic function and size over OMT alone.

In vitro and preliminary in vivo validation of echo particle image velocimetry in carotid vascular imaging.

Noninvasive, easy-to-use and accurate measurements of wall shear stress (WSS) in human blood vessels have always been challenging in clinical applications. Echo particle image velocimetry (Echo PIV) has shown promise for clinical measurements of local hemodynamics and wall shear rate. Thus far, however, the method has only been validated under simple flow conditions. In this study, we validated Echo PIV under in vitro and in vivo conditions. For in vitro validation, we used an anatomically correct, compliant carotid bifurcation flow phantom with pulsatile flow conditions, using optical particle image velocimetry (optical PIV) as the reference standard. For in vivo validation, we compared Echo PIV-derived 2-D velocity fields obtained at the carotid bifurcation in five normal subjects against phase-contrast magnetic resonance imaging (PC-MRI)-derived velocity measurements obtained at the same locations. For both studies, time-dependent, 2-D, two-component velocity vectors; peak/centerline velocity, flow rate and wall shear rate (WSR) waveforms at the common carotid artery (CCA), carotid bifurcation and distal internal carotid artery (ICA) were examined. Linear regression, correlation analysis and Bland-Altman analysis were used to quantify the agreement of different waveforms measured by the two techniques. In vitro results showed that Echo PIV produced good images of time-dependent velocity vector maps over the cardiac cycle with excellent temporal (up to 0.7 ms) and spatial (∼0.5 mm) resolutions and quality, comparable with optical PIV results. Further, good agreement was found between Echo PIV and optical PIV results for velocity and WSR measurements. In vivo results also showed good agreement between Echo PIV velocities and phase contrast MRI velocities. We conclude that Echo PIV provides accurate velocity vector and WSR measurements in the carotid bifurcation and has significant potential as a clinical tool for cardiovascular hemodynamics evaluation.

Cardiovascular magnetic resonance for the interventionist.

Cardiovascular magnetic resonance (CMR) continues to provide exceptional quality images of cardiac and major vessel anatomy, but recent advances now permit a rapid, robust assessment of a diverse spectrum of functional and physiological parameters. In the routine CMR investigation of ischaemic heart disease, clinicians are now faced with an array of real time on-line rest and stress images that encompass cardiac function, perfusion, the presence of infarcted, viable and ischaemic myocardium, as well as metabolism. The implementation of cardiac dedicated scanners, the ever increasing array of diagnostic information available, and the increasing clinical demand for all forms of CMR investigation has seen the integration of MRI into cardiology, with cardiologists becoming increasingly involved at every stage. With the advent of CMR directed intervention and CMR directed therapy, together with the development of combined cardiovascular interventional CMR laboratories, interventional cardiologists in particular now themselves in the forefront of this pioneering technology.This article reviews the key areas of CMR that pertain to the modern interventional cardiologist.

Myocardial contrast echocardiography predicts left ventricular remodelling after acute myocardial infarction.

BACKGROUND: We investigated whether the extent of residual myocardial viability demonstrated by myocardial contrast echocardiography (MCE) predicts the degree of left ventricular (LV) remodelling after acute myocardial infarction as assessed by cardiovascular magnetic resonance. METHODS: Accordingly, 25 patients underwent MCE 5 to 7 days after acute myocardial infarction followed by cardiovascular magnetic resonance assessment of LV end-diastolic volume, LV end-systolic volume, and LV ejection fraction. A contrast perfusion index was calculated within the infarct-related territory. RESULTS: LV end-diastolic and end-systolic volumes were significantly smaller (138 +/- 38 vs 188 +/- 43 mL, P =.008, and 86 +/- 35 vs 119 +/- 49 mL, P =.01, respectively) and LV ejection fraction was significantly higher (52 +/- 5.4 vs 31.5 +/- 3.2%, P> =.02) in patients showing good myocardial viability (contrast perfusion index