Novel insights into an old controversy: is coronary artery ectasia a variant of coronary atherosclerosis?

Coronary dilatation after heart transplantation

BACKGROUND

The angiographic incidence of coronary dilatation (CD) in the nontransplant population is approximately 0.2% to 5%. The endothelial-dependent and -independent causes for CD are postulated. So far, the incidence and prognosis of CD after heart transplantation is unknown.

METHODS

We retrospectively analyzed the annual coronary angiographies of 688 heart transplant recipients regarding the incidence of CD (defined as ≥1.5-fold localized increased vessel diameter or diffuse dilatation involving more than 50% of the coronary artery). A subgroup analysis of coronary epicardial (quantitative angiography) and microvascular (doppler flow measurement) vasomotor function in response to acetylcholine (endothelial dependent) and adenosine (endothelial independent) as well as intravascular ultrasound was performed in 177 patients.

RESULTS

CD was detectable in 26 patients (3.8%) and was associated with stenosing coronary artery disease in 27% of the patients. Segments with CD tended to have less intimal hyperplasia compared with nondilated segments. A diffuse dilatation (type I-II) was present in 63% of the recipients. The right coronary artery was always involved. The patients with CD (5 of 177) showed a 31% reduced flow velocity in the dilated coronaries compared with the nondilated coronary arteries (P=0.03). Microvascular endothelial-independent function was impaired in CD by -29% (coronary flow reserve mean 1.9 vs. 2.7; P=0.04), whereas endothelial-dependent response was unchanged. Epicardial endothelial-dependent and -independent responses were not different between the groups. Incidence of CD was not associated with limited survival.

CONCLUSION

The incidence of CD in the nontransplant population is similar to that in the transplanted population. However, the latter shows a more diffuse extent. Heart transplantation patients with CD had microvascular endothelial-independent functional limitations and flow deceleration, whereas survival was not affected.

Antiendothelial cell antibodies in patients with coronary artery ectasia

BACKGROUND

The mechanisms involved in the pathogenesis of coronary artery ectasia (CAE) have not been elucidated. Circulating antiendothelial cell antibodies (AECA) are often detectable in systemic vasculitis and have been implicated in the pathogenesis of endothelial injury. Their prevalence in CAE is not known.

METHODS AND RESULTS

Out of 475 consecutive patients subjected to coronary angiography, 27 patients were diagnosed with CAE. Thirty patients matched for age, body mass index, sex, and coronary artery disease prevalence, served as controls. Serum AECA of IgG, IgM, and IgA isotypes were detected using a cell-based enzyme-linked immunosorbent assay (ELISA). Antinuclear antibodies (ANA) and antineutrophil cytoplasmic antibodies (ANCA) were detected using indirect immunofluorescence. IgG and IgM anticardiolipin antibodies (aCL) were detected using commercial ELISA. The prevalence of ANA and ANCA was similar in CAE patients and controls (33.3 vs. 43.3%, and 3.3 vs. 7.4%, respectively). There was no significant difference in IgG or IgM aCL reactivity between patients and controls. Both CAE patients and controls were negative for IgG AECA. The frequency of IgM AECA positivity was similar in CAE patients and controls. The prevalence of AECA of the IgA isotype was significantly higher in CAE patients (37.0 vs. 10%, P<0.05).

CONCLUSION

There is increased prevalence of circulating AECA of the IgA isotype in patients with CAE. This provides evidence for a role of autoimmunity in the pathogenesis of certain cases of CAE.

Transgenic expression of matrix metalloproteinase-2 induces coronary artery ectasia

Coronary artery ectasia (CAE) is generally diagnosed in patients undergoing arteriography for presumptive atherosclerotic coronary artery disease. CAE is commonly considered as a variant of atherosclerotic disease; however, recent studies suggest that CAE is the result of a systemic vascular disorder. There is increasing evidence that aneurysmal vascular disease is a systemic disorder characterized by enhanced expression of pro-inflammatory cytokines and increased synthesis of enzymes capable of degrading elastin and other components of the vascular wall. Matrix metalloproteinase-2 degrades a number of extracellular substrates, including elastin and has been shown to play a critical role in the development of abdominal aortic aneurysms. This study characterizes the development of CAE in a unique murine transgenic model with cardiac-specific expression of active MMP-2. Transgenic mice were engineered to express an active form of MMP-2 under control of the α-myosin heavy chain promoter. Coronary artery diameters were quantified, along with studies of arterial structure, elastin integrity and vascular expression of the MMP-2 transgene. Latex casts quantified total coronary artery volumes and arterial branching. Mid-ventricular coronary luminal areas were increased in the MMP-2 transgenics, coupled with foci of aneurysmal dilation, ectasia and perivascular fibrosis. There was no evidence for atherogenesis. Coronary vascular elastin integrity was compromised and coupled with inflammatory cell infiltration. Latex casts of the coronary arteries displayed ectasia with fusiform dilatation. The MMP-2 transgenic closely replicates human CAE and supports a critical and initiating role for this enzyme in the pathogenesis of this disorder.

The relationship between coronary slow flow phenomenon and coronary calcium score

AIM

Coronary slow flow phenomenon (CSFP) is an angiographic finding characterized by delayed distal vessel opacification without any significant epicardial coronary artery disease. Several studies have suggested that CSFP might be a form of atherosclerosis. The present study was aimed to investigate the relationship between CSFP and coronary artery calcification, which is one of the clear-cut indicators of coronary atherosclerotic plaque, by using computerized tomography.

METHOD

Fifty-five patients were included in the study. The coronary arteries of all patients were shown by angiography to be normal. Coronary slow flow (CSF) patterns were evaluated by the thrombolysis in myocardial infarction frame count (TFC) method. Patients with normal coronary arteries and CSF were allocated into the CSF group, and patients with normal coronary arteries and normal coronary flow were allocated into the control group. Coronary artery calcium (CAC) score was measured in 28 patients with CSF and in 27 controls by 64-slice computerized tomography.

RESULTS

The CSF and control groups were similar with respect to age, gender, smoking status, presence of hypertension and diabetes mellitus, cholesterol profiles, and Framingham risk scores (p>0.05). The CSF and control groups were not significantly different with respect to CAC score (p>0.05). Sub-group analysis of cardiac risk factors in patients with or without coronary artery calcification revealed that advanced age and low high density lipoprotein (HDL) levels were significantly associated with coronary artery calcification. There wasn't any relationship between coronary slow flow and cardiac risk factors or coronary calcium scores.

CONCLUSION

In the present study, no association was found between the CSFP and calcified atherosclerosis. Additionally, it was demonstrated that, among the cardiac risk factors, advanced age and low HDL levels were associated with coronary artery calcification.

Outcome of Primary Percutaneous Intervention in Patients With Infarct-Related Coronary Artery Ectasia

Data related to the incidence and clinical outcome of acute myocardial infarction (AMI) in patients with preexisting coronary artery ectasia (CAE) are limited. We assessed whether infarct-related artery ectasia (EIRA) indicates an untoward clinical outcome in patients with AMI undergoing primary percutaneous coronary intervention (pPCI). Consecutive patients (n = 643) who presented with AMI and were treated with pPCI were analyzed retrospectively; 31 patients (4.8%) had EIRA. Patients who had EIRA were significantly younger and had higher incidence of hypertension, previous stroke, smoking, inferior wall AMI, and Killip score >1. Infarct-related artery ectasia was more frequent in the right coronary artery (RCA). Impaired epicardial arterial flow, thrombus burden score of infarct-related artery (IRA), impaired Thrombolysis in Myocardial Infarction (TIMI) Myocardial Perfusion Grade, and distal embolization were significantly higher whereas ST-segment resolution and collateral vascular development were significantly lower in patients with EIRA. Infarct-related artery ectasia was an independent predictor of adverse outcome (odds ratio: 0.197; 95% confidence interval [CI]: 0.062-0.633; P = .006).