Optical coherence tomography in coronary atherosclerosis assessment and intervention

Since optical coherence tomography (OCT) was first performed in humans two decades ago, this imaging modality has been widely adopted in research on coronary atherosclerosis and adopted clinically for the optimization of percutaneous coronary intervention. In the past 10 years, substantial advances have been made in the understanding of in vivo vascular biology using OCT. Identification by OCT of culprit plaque pathology could potentially lead to a major shift in the management of patients with acute coronary syndromes. Detection by OCT of healed coronary plaque has been important in our understanding of the mechanisms involved in plaque destabilization and healing with the rapid progression of atherosclerosis. Accurate detection by OCT of sequelae from percutaneous coronary interventions that might be missed by angiography could improve clinical outcomes. In addition, OCT has become an essential diagnostic modality for myocardial infarction with non-obstructive coronary arteries. Insight into neoatherosclerosis from OCT could improve our understanding of the mechanisms of very late stent thrombosis. The appropriate use of OCT depends on accurate interpretation and understanding of the clinical significance of OCT findings. In this Review, we summarize the state of the art in cardiac OCT and facilitate the uniform use of this modality in coronary atherosclerosis. Contributions have been made by clinicians and investigators worldwide with extensive experience in OCT, with the aim that this document will serve as a standard reference for future research and clinical application.

Optical Coherence Tomography of Coronary Plaque Progression and Destabilization: JACC Focus Seminar Part 3/3

The development of optical coherence tomography (OCT) has revolutionized our understanding of coronary artery disease. In vivo OCT research has paralleled with advances in computational fluid dynamics, providing additional insights in the various hemodynamic factors influencing plaque growth and stability. Recent OCT studies introduced a new concept of plaque healing in relation to clinical presentation. In addition to known mechanisms of acute coronary syndromes such as plaque rupture and plaque erosion, a new classification of calcified plaque was recently reported. This review will focus on important new insights that OCT has provided in recent years into coronary plaque development, progression, and destabilization, with a focus on the role of local hemodynamics and endothelial shear stress, the layered plaque (signature of previous subclinical plaque destabilization and healing), and the calcified culprit plaque.

2-Year Outcomes for Transcatheter Repair in Patients With Mitral Regurgitation From the CLASP Study

OBJECTIVES

This study reports 2-year outcomes from the multicenter, prospective, single-arm CLASP study with functional mitral regurgitation (FMR) and degenerative MR (DMR) analysis.

BACKGROUND

Transcatheter repair is a favorable option to treat MR. Long-term prognostic impact of the PASCAL transcatheter valve repair system in patients with clinically significant MR remains to be established.

METHODS

Patients had clinically significant MR ≥3+ as evaluated by the echocardiographic core laboratory and were deemed candidates for transcatheter repair by the heart team. Assessments were performed by clinical events committee to 1 year (site-reported thereafter) and core laboratory to 2 years.

RESULTS

A total of 124 patients (69% FMR, 31% DMR) were enrolled with a mean age of 75 years, 56% were male, 60% were New York Heart Association functional class III to IVa, and 100% had MR ≥3+. At 2 years, Kaplan-Meier estimates showed 80% survival (72% FMR, 94% DMR) and 84% freedom from heart failure (HF) hospitalization (78% FMR, 97% DMR), with 85% reduction in annualized HF hospitalization rate (81% FMR, 98% DMR). MR ≤1+ was achieved in 78% of patients (84% FMR, 71% DMR) and MR ≤2+ was achieved in 97% (95% FMR, 100% DMR) (all p < 0.001). Left ventricular end-diastolic volume decreased by 33 ml (p < 0.001); 93% of patients were in New York Heart Association functional class I to II (p < 0.001).

CONCLUSIONS

The PASCAL repair system demonstrated sustained favorable outcomes at 2 years in FMR and DMR patients. Results showed high survival and freedom from HF rehospitalization rates with a significantly reduced annualized HF hospitalization rate. Durable MR reduction was achieved with evidence of left ventricular reverse remodeling and significant improvement in functional status. The CLASP IID/IIF randomized pivotal trial is ongoing.

Cerebral Microcirculation during Experimental Normovolaemic Anemia

Anemia is accepted among critically ill patients as an alternative to elective blood transfusion. This practice has been extrapolated to head injury patients with only one study comparing the effects of mild anemia on neurological outcome. There are no studies quantifying microcirculation during anemia. Experimental studies suggest that anemia leads to cerebral hypoxia and increased rates of infarction, but the lack of clinical equipoise, when testing the cerebral effects of transfusion among critically injured patients, supports the need of experimental studies. The aim of this study was to quantify cerebral microcirculation and the potential presence of axonal damage in an experimental model exposed to normovolaemic anemia, with the intention of describing possible limitations within management practices in critically ill patients. Under non-recovered anesthesia, six Merino sheep were instrumented using an intracardiac transeptal catheter to inject coded microspheres into the left atrium to ensure systemic and non-chaotic distribution. Cytometric analyses quantified cerebral microcirculation at specific regions of the brain. Amyloid precursor protein staining was used as an indicator of axonal damage. Animals were exposed to normovolaemic anemia by blood extractions from the indwelling arterial catheter with simultaneous fluid replacement through a venous central catheter. Simultaneous data recording from cerebral tissue oxygenation, intracranial pressure, and cardiac output was monitored. A regression model was used to examine the effects of anemia on microcirculation with a mixed model to control for repeated measures. Homogeneous and normal cerebral microcirculation with no evidence of axonal damage was present in all cerebral regions, with no temporal variability, concluding that acute normovolaemic anemia does not result in short-term effects on cerebral microcirculation in the ovine brain.

Next generation TAVI with the Lotus Valve System: a repositionable and fully retrievable transcatheter aortic valve prosthesis

Transcatheter aortic valve implantation (TAVI) is the new standard of care for selected patients with severe symptomatic aortic stenosis who are at high risk for surgical aortic valve replacement (AVR), or are inoperable. Multicentre randomised controlled trials have demonstrated equivalent or superior clinical outcomes for TAVI compared to AVR in carefully selected patient cohorts. A number of important limitations were observed with early generation TAVI valves and their delivery systems, and rapid evolution of the technology continues. The Lotus Valve System aims to address a number of these limitations - it is repositionable and retrievable, and has an adaptive seal to prevent paravalvular aortic regurgitation. Early clinical outcomes for the Lotus Valve System have recently been published with promising results in terms of paravalvular regurgitation and repositionability.

Takotsubo cardiomyopathy: an Australian single centre experience with medium term follow up

BACKGROUND

Takotsubo cardiomyopathy (TC) is increasingly recognised in patients presenting with features of acute coronary syndrome. We present a single centre experience of TC with medium term follow up.

METHODS

Fifty-two consecutive patients presenting with a diagnosis of TC were included. The clinical presentation, complications, baseline and follow-up echocardiograms and cardiac magnetic resonance imaging were analysed.

RESULTS

Fifty-one patients were female. A stressful event preceded presentation in 37 (71%) patients. Chest pain was the most common symptom (83%). Two patients presented with an out-of-hospital cardiac arrest. ST segment elevation (40%) and global T wave inversion (44%) were the most frequent electrocardiogram changes. Left ventricular assessment demonstrated typical apical ballooning in 41 patients and 11 patients demonstrated the mid-wall variant. In-hospital complications occurred in 11 patients (21%) and included acute pulmonary oedema (n = 2), cardiogenic shock (n = 5); two of whom had a significant left ventricular outflow gradient, atrial fibrillation (n = 1), left ventricular thrombus (n = 2) and a cerebrovascular event (n = 2). Left ventricular function at presentation and follow up was compared in 40 patients. The mean ejection fraction in this group at presentation was 47% (20-70%) compared with that at follow up of 63% (44-76%). There were no significant complications or recurrences at follow up.

CONCLUSIONS

While TC is a reversible condition with low rates of complications and recurrence at follow up it is, as demonstrated in our cohort, associated with significant in-hospital morbidity in a proportion of patients.

CT angiography with cardiac MRI: non-invasive functional and anatomical assessment for the etiology in newly diagnosed heart failure

Exclusion of ischemia is important in patients with newly diagnosed systolic heart failure (HF). We prospectively compared standard-of-care invasive catheter angiography (iCA) and echocardiography to a novel non-invasive strategy of both Coronary Computed Tomographic Angiography (CCTA) and Cardiovascular MRI (CMR) to determine the etiology of myocardial dysfunction Prospective data were collected from consecutive patients referred for iCA to investigate echocardiographically-confirmed new onset HF. CMR (1.5T GE) and dual source CCTA were performed within 2-7 days of iCA. Results were blinded and separately analyzed by expert readers. 426 coronary segments from 28 prospectively enrolled patients were analyzed by CCTA and quantitative iCA. The per-patient sensitivity and specificity of CCTA was 100% and 90%, respectively, negative predictive value (NPV) 100%, positive predictive value (PPV) 78%. Mean ejection fraction by CMR was 24%. Presence of ischemic-type LGE on CMR conferred a 67% sensitivity, 100% specificity, 90% NPV and 100% PPV. Combining CCTA with CMR conferred 100% specificity, 100% sensitivity, 100% PPV and 100% NPV for detection or exclusion of coronary disease. In patients with negative CCTA all invasive angiograms could have been avoided. In addition, two patients with no ischemic LGE by CMR had severe coronary disease on both CCTA and iCA, indicating global hibernation. This is a noteworthy finding in contrast to previous reports which suggested that absence of LGE rules out significant CAD. CCTA with CMR in newly-diagnosed HF enables non-invasive assessment of coronary artery disease, the severity and etiology of myocardial dysfunction and defines suitability for revascularization. Absence of ischemic-type LGE at CMR does not exclude CAD as a cause of LV dysfunction. A first-line strategy of functional and anatomic imaging with CMR and CCTA appears appropriate in newly diagnosed HF.

Comparison of activated clotting times obtained using Hemochron and Medtronic analysers in patients receiving anti-thrombin therapy during cardiac catheterisation

Accurate monitoring of anti-thrombin therapy with activated clotting time (ACT) is important to prevent thrombotic and haemorrhagic complications during cardiac catheterisation. Significant variability in ACT tests exists when different analysers are used. Our objective was to compare ACT results obtained using Hemochron and Medtronic ACT PLUS devices and antiXa activity in patients undergoing cardiac catheterisation. Thirty-two patients who received unfractionated heparin or argatroban therapy during cardiac catheterisation were enrolled. Blood sampling was performed to determine ACT values using Hemochron and Medtronic (with high-range cartridges) devices in all patients (n = 130 pairs), and anti-Xa activity following heparin administration. In the heparin group, ACT tests (n = 95 pairs) showed very good correlation (r = 0.84, y = 1.31x-0.81; p<0.001). However, Hemochron values were consistently higher and the difference more pronounced with increasing ACT (for ACT>150 sec, mean difference 65 +/- 48 sec; p<0.001). Both Hemochron and Medtronic ACT tests correlated well with plasma anti-Xa levels (r = 0.85, r = 0.81, respectively; p<0.001); Hemochron ACT>300 sec corresponded to anti-Xa>1.48 IU/ml. With concomitant eptifibatide therapy, the divergence in ACT was greater compared to heparin alone. In the argatroban group, ACT tests (n = 35 pairs) demonstrated excellent correlation (r = 0.94, y = 0.61x+79.9; p<0.001). In contrast to the heparin group, ACT values were higher with Medtronic compared to Hemochron. Therefore, despite good correlation between Hemochron and Medtronic ACT results, and strong association with anti-Xa activity, Medtronic ACT values were consistently lower compared to Hemochron following heparin anticoagulation. Paradoxically, Medtronic ACT results were higher after argatroban therapy. Understanding this discrepancy is crucial when using ACT to guide invasive cardiac procedures.

Association of leukocyte and neutrophil counts with infarct size, left ventricular function and outcomes after percutaneous coronary intervention for ST-elevation myocardial infarction

Elevated leukocyte count during ST-segment elevation myocardial infarction is associated with adverse clinical outcomes. Whether increased leukocyte count after primary percutaneous coronary intervention (PCI) directly reflects larger infarct size and left ventricular impairment is not known. The aim of this study was to assess the relation between leukocyte and neutrophil counts with infarct size and the left ventricular ejection fraction (LVEF) after primary PCI. Three hundred sixty-three patients from the Evaluation of MCC-135 for Left Ventricular Salvage in Acute Myocardial Infarction (EVOLVE) study, a randomized, double-blind, placebo-controlled trial assessing the efficacy of intracellular calcium modulator as an adjunct to primary PCI in patients with first ST-segment elevation myocardial infarctions, were evaluated. Total and differential leukocyte counts were measured before and serially after PCI. Infarct size and the LVEF were assessed using single-photon emission computed tomography after 5 and 30 days, and patients were followed up to 180 days. Total leukocyte and neutrophil counts obtained 24 hours after PCI were significantly correlated with infarct size (r = 0.34 and 0.37, respectively, p <0.001) and inversely correlated with the LVEF (r = -0.20 and -0.22, respectively, p <0.001). Patients with elevated leukocyte and neutrophil counts had larger infarct sizes (12.5% vs 5% and 13.5% vs 5%, respectively, p <0.001). The highest neutrophil quartile was associated with increased 180-day composite cardiac events (19% vs 20% vs 23% vs 45%, log-rank p <0.001). Elevated leukocyte and neutrophil counts independently predicted adverse cardiac events (hazard ratios 2.5 and 2.2, respectively, p = 0.001). In conclusion, elevated leukocyte and neutrophil counts after primary PCI in patients with ST-segment elevation myocardial infarctions are directly related to myocardial infarct size and the LVEF and are independent predictors of cardiovascular outcomes.

Comparison of coronary plaque characteristics between diabetic and non-diabetic subjects: An in vivo optical coherence tomography study

AIMS

Postmortem series have reported that subjects with diabetes mellitus have coronary plaques with larger necrotic cores and increased macrophage infiltration. Optical coherence tomography (OCT) is a high-resolution imaging modality that allows in vivo characterization of atherosclerotic plaques. Using OCT imaging, we compared in vivo plaque characteristics between diabetic and non-diabetic subjects.

METHODS

Sixty-three patients undergoing cardiac catheterization were enrolled. OCT imaging was performed in culprit coronary arteries. Assessment of plaque lipid content, fibrous cap thickness and frequency of thin-cap fibroatheroma were made independently. Macrophage density was determined from the optical signal within fibrous cap.

RESULTS

Eighty-two plaques in total were imaged (19 diabetic vs. 63 non-diabetic). There were no significant differences in frequency of lipid-rich plaques (68% vs. 71%; P=0.78), thin-cap fibroatheroma (29% vs. 36%; P=0.76) or minimum fibrous cap thickness (66.6microm vs. 62.9microm; P=0.87) between diabetic and non-diabetic patients. Fibrous cap macrophage density was higher in lipid-rich plaques (P=0.01) but showed no difference between diabetic and non-diabetic patients (5.94% vs. 5.94%; P=0.37).

CONCLUSIONS

There were no significant differences in culprit vessel plaque characteristics between diabetic and non-diabetic patients presenting with coronary artery disease. This represents the first study to characterize coronary plaques in diabetic patients using OCT.

Cardiac transplantation and aortic coarctation repair in severe heart failure

A 37-year-old man presented with severe dilated cardiomyopathy secondary to occult aortic coarctation. He was successfully managed with combined orthotopic heart transplantation and aortic coarctation repair.

In-vivo comparison of coronary plaque characteristics using optical coherence tomography in women vs. men with acute coronary syndrome

OBJECTIVE

Women with acute coronary syndromes (ACS) have worse outcomes than men. Data on sex differences of culprit plaque characteristics are lacking. Intravascular optical coherence tomography (OCT) is a high-resolution imaging technique capable of in-vivo plaque characterization. The aim of this study was to compare culprit plaque characteristics in women and men presenting with ACS.

METHODS

Patients undergoing coronary angiography after ACS were enrolled. We performed OCT imaging on the culprit lesions. Previously validated criteria for OCT plaque characterization were used: lipid was quantified on cross-sectional image and lipid-rich plaque was defined as > or = 2 involved quadrants; fibrous cap thickness was measured at the thinnest point and thin-cap fibroatheroma was defined as lipid-rich plaque with fibrous cap thickness less than 65 microm.

RESULTS

Forty-two patients (33 men and nine women) were included. No significant sex differences were found in baseline characteristics. Lipid-rich plaques were identified in majority of patients. No significant difference, however, was seen in the frequency of lipid-rich plaques, thin-cap fibroatheroma or minimum fibrous cap thickness (79 vs. 89%; 45 vs. 67%; 53.8 vs. 45.4 microm, respectively; P=NS) between men and women. Incidence of calcification, thrombus and plaque disruption were also similar.

CONCLUSIONS

No significant sex difference was seen in culprit plaque characteristics determined by OCT imaging in patients who presented with ACS.

Relationship between a systemic inflammatory marker, plaque inflammation, and plaque characteristics determined by intravascular optical coherence tomography

OBJECTIVE

The purpose of this study was to evaluate the relationships between the peripheral white blood cell (WBC) count, local plaque fibrous cap macrophage density, and the morphological features and presence of thin-cap fibroatheromas (TCFA) identified by optical coherence tomography (OCT).

METHODS AND RESULTS

OCT was performed in patients undergoing catheterization. Images were analyzed using validated criteria for plaque characteristics. Baseline WBC count correlated with macrophage density (r=0.483, P<0.001). Both parameters were associated with lipid-rich plaque and correlated inversely with plaque fibrous cap thickness (r=-0.547 for macrophage density and -0.423 for WBC count, P<0.015). Plaques classified as TCFA had a higher median macrophage density than non-TCFA plaques (7.4 versus 4.99, P<0.001). Patients with TCFA had a higher WBC count compared with those without TCFA (11.0 versus 7.9, P=0.007). Receiver operator curves for WBC count, macrophage density, and these combined parameters for prediction of TCFA showed the area under the curves were 0.88, 0.91, and 0.97 (P<0.001), respectively.

CONCLUSION

This study provides the first in vivo data linking the peripheral WBC count, plaque fibrous cap macrophage density, and the characteristics and presence of TCFA. Macrophage density correlated with the WBC count, and both parameters independently and particularly in combination predict the presence of TCFA.

Coronary stent malapposition as a result of a post-stenotic aneurysm detected by optical coherence tomography

Stent malapposition remains an important cause of complications following stent implantation. Stent underexpansion is a frequent cause of this. We describe a case of coronary stent malapposition as a result of a post-stenotic aneurysm. Both the malapposition and its etiology were clearly demonstrated by optical coherence tomography, a novel high-resolution imaging technology.

Initial Q waves accompanying ST-segment elevation at presentation of acute myocardial infarction and 30-day mortality in patients given streptokinase therapy: an analysis from HERO-2

BACKGROUND

The presence of pathological Q waves in the infarct leads on the surface electrocardiogram in an ST-elevation acute myocardial infarction indicates myocardial necrosis. Clinically it might be difficult to ascertain the onset of acute myocardial infarction. Our aim was to assess whether the presence or absence of Q waves at presentation could be used as an indicator of the duration of acute myocardial infarction and predict mortality.

METHODS

15,222 patients with ST-elevation acute myocardial infarction and normal intraventricular conduction were randomly assigned streptokinase and aspirin plus bivalirudin or unfractionated heparin in the HERO-2 trial; randomisation did not alter 30-day mortality. 10,244 patients (67%) had Q waves in the infarct territory at the time of randomisation, and 4978 (33%) did not. The primary endpoint was 30-day mortality.

FINDINGS

There were more deaths at 30 days in patients with initial Q waves than in those without (1044 [10%] vs 344 [7%], p<0.0001). These findings were similar in patients with a first acute myocardial infarction and when stratified by time to randomisation (0-2, >2-4, >4 h) and by acute myocardial infarction location (anterior or inferior). Both the presence of initial Q waves and time to randomisation were positive univariate predictors, but only the presence of initial Q waves independently predicted 30-day mortality on multivariate analysis (adjusted OR 1.44, 95% CI 1.25-1.65 with clinical indices, and 1.31, 1.12-1.54 with clinical plus ST indices included as predictors).

INTERPRETATION

The presence of Q waves in the infarct leads at presentation of ST-elevation acute myocardial infarction independently predicts higher 30-day mortality in patients treated with fibrinolytic therapy. Therefore, a more aggressive approach to reperfusion might be warranted in these patients.

Drug Insight: statin use in the elderly

The elderly represent a notable proportion of patients who present with myocardial infarction or acute coronary syndromes. This subgroup of patients also experiences a higher incidence of adverse outcomes than younger age-groups, and, therefore, has more to gain from effective, evidence-based therapies. The efficacy of statins in secondary cardiovascular disease prevention is firmly established. The starting of therapy soon after an acute coronary event has been shown to provide added benefit. Uncertainties about the effectiveness of statins in the elderly, however, have resulted in their underuse in this population. In this review we evaluate the evidence for statin use in this important and increasingly large group of patients.

Patients With Prolonged Ischemic Chest Pain and Presumed-New Left Bundle Branch Block Have Heterogeneous Outcomes Depending on the Presence of ST-Segment Changes

OBJECTIVES

The purpose of this research was to examine the prognostic value of ST-segment changes (concordant ST-segment elevation and/or precordial V1 to V3 ST-segment depression) during presumed-new left bundle branch block (LBBB) in patients receiving fibrinolytic therapy.

BACKGROUND

These patients are often considered high-risk, but their outcome is not well-defined.

METHODS

The Hirulog and Early Reperfusion or Occlusion (HERO)-2 trial compared bivalirudin with heparin in patients receiving streptokinase for ST-segment elevation or presumed-new LBBB. Each patient with LBBB was matched with a control (with normal intraventricular conduction) for age, gender, pulse rate, systolic blood pressure, Killip class, and region.

RESULTS

A total of 300 patients had LBBB (92 with and 208 without ST-segment changes) and 15,340 had normal conduction. Acute myocardial infarction (AMI) occurred in 80.7% of LBBB patients and 88.7% of controls (p = 0.006). ST-segment changes were specific (96.6%) but not sensitive (37.8%) for enzymatic diagnosis of AMI. Mortality at 30 days was similar in LBBB patients with ST-segment changes (21.7%) and controls (25.0%, p = 0.563), but lower in LBBB patients without ST-segment changes than in controls (13.5% vs. 21.6%, p = 0.022). In the whole HERO-2 cohort, the LBBB patients with ST-segment changes had higher mortality than patients with normal conduction (odds ratio [OR] 1.37, 95% confidence interval [CI] 0.78 to 2.42). The LBBB patients without ST-segment changes had lower mortality than patients with normal conduction (OR 0.52, 95% CI 0.33 to 0.80).

CONCLUSIONS

ST-segment changes during LBBB are specific for the diagnosis of AMI and predict 30-day mortality; LBBB patients without ST-segment changes have lower adjusted 30-day mortality than those with normal conduction. Trials are required to determine the best treatment for high-risk and low-risk patients with LBBB.