Implants and contact allergy: are sensitizing metals released as haptens from coronary stents?

BACKGROUND: The possible impact of metal release from coronary artery stents has, with their increased use, become a concern. OBJECTIVES: To study in vitro metal release in biologically relevant milieu from coronary stents made of different alloys. MATERIALS AND METHOD: Coronary stents in common use in a department of cardiology at the time of the study were tested. A previously described in vitro technique was used, whereby the stents were kept in the extraction media for a week. Two different extraction media were used to show the necessity of studying the actual biological surrounding of the implant when metal release is investigated. Metal release was determined with atomic absorption spectrometry. RESULTS: In this study, we show metal release from stents after immersion in extraction media of artificial sweat and cysteine solution, as illustrative media. CONCLUSION: Metal release from coronary stents is shown. The magnitude of release is influenced by several factors. The extent to which metal release in vitro has potential biological effects, in terms of elicitation of an allergic reaction or induction of sensitization, in vivo needs to be explored. However, as metal release from an implant in a biologically appropriate medium has been established, better risk assessments in relation to delayed hypersensitivity may be undertaken.

Troponin I and Creatine Kinase MB do not provide comparable information after PCI.

OBJECTIVES: To compare cardiac troponin I (cTnI) and creatine kinase-MB (CK-MB) after PCI in cases with normal baseline levels of both biomarkers. DESIGN: cTnI and CK-MB after PCI were stratified as multiples of the 99(th) percent upper reference limit (99%URL) and compared to each other in 489 patients. Post-PCI levels > three times 99%URL were classified as procedure-related infarctions. Results. After PCI, CK-MB was > 3x 99%URL in 58/486 patients (12%) and cTnI > 3x 99%URL in 292/487 patients (60%). cTnI was > 10x 99%URL in all cases with infarction according to CK-MB but CK-MB was often normal despite elevated cTnI. There was an only minimal overlap between two infarction populations, those with cTnI in the range from 1x to 10x 99%URL and those with CK-MB 1x to 10x 99%URL. CONCLUSIONS: With the present quantification scales, infarction rate after PCI is > five-fold higher with cTnI than with CK-MB.

Thrombotic occlusion of all left coronary branches in a young woman with severe ulcerative colitis.

Background. The thrombosis risk is increased in active ulcerative colitis. The limited number of reported complications have predominantly been cerebrovascular but other vessel territories may also be affected. Patient. During a severe attack of ulcerative colitis a 37-year-old woman suffered occlusion of all left coronary artery branches. Serial angiographies showed progressive recanalisation of the coronary arteries during anticoagulation, but no atherosclerotic stenosis. The cause of infarction was thus considered to be an extensive coronary thrombosis. However, a large battery of blood tests failed to identify any procoagulant abnormality. Conclusion. Evidence is now accumulating that the increased thrombosis risk also may involve the coronary arteries, even in young patients. To the best of our knowledge this is the third reported case of myocardial infarction despite angiographically normal coronary arteries in a patient with active ulcerative colitis. The extent of affected myocardium was in this case exceptionally large.

A correlation found between contact allergy to stent material and restenosis of the coronary arteries.

BACKGROUND: Metallic implants, stents, are increasingly being used especially in patients with stenosis of the cardiac vessels. Ten to thirty per cent of the patients suffer from restenosis regardless of aetiology. We have shown increased frequency of contact allergy to stent metals in stented patients. OBJECTIVES: To we evaluate whether contact allergy to stent material is a risk factor for restenosis. METHODS: Patients with stainless steel stents, with or without gold plating, were epicutaneously tested and answered a questionnaire. The restenosis rate was evaluated. RESULTS: We found a correlation between contact allergy to gold, gold stent, and restenosis (OR 2.3, CI 1.0-5.1, P = 0.04). The risk for restenosis was threefold increased when the patient was gold allergic and stented with a gold-plated stent. An increased degree of chest pain in gold-allergic patients stented with gold-plated stent was found. CONCLUSIONS: We found a correlation between contact allergy to gold, gold-stent, and restenosis. It may be of importance to consider contact allergy when developing new materials for stenting.

Inflammatory activity increases with haemoglobin A1c in patients with acute coronary syndrome.

OBJECTIVE: To study the relationship between inflammation, diabetes and HbA(1)c levels in patients with acute coronary syndrome (ACS). DESIGN: Single-centre cross-sectional study comprising 688 consecutive patients with ACS (108 with diabetes) and 341 with stable coronary artery disease (SCAD) (51 with diabetes). High-sensitive C-reactive protein (hsCRP), albumin and fibrinogen concentrations, erythrocyte sedimentation rates (ESR) and leukocyte counts were measured. RESULTS: hsCRP, fibrinogen and ESR levels were higher and albumin lower in ACS patients. ESR was higher, albumin lower and hsCRP borderline significantly higher (p=0.053) in ACS patient with diabetes compared to those without. All inflammatory markers were associated with HbA(1)c in all 688 ACS patients as well as in 540 non-diabetic ACS patients with normal HbA(1)c. In multivariate analyses, all inflammatory markers were independently associated with HbA(1)c in the entire ACS group, regardless of diabetes being present or not. When non-diabetic ACS patients were analyzed separately, only ESR and leukocyte counts were independently correlated with HbA(1)c. CONCLUSIONS: Patients with ACS had increased inflammatory activity, which increased with HbA(1)c levels in patients who neither had a history of diabetes nor HbA(1)c above normal, and was further exaggerated in the presence of diabetes.

Markers of inflammation in patients with coronary artery disease are also associated with glycosylated haemoglobin A1c within the normal range.

AIMS: Diabetes is a risk factor for atherosclerosis and low-degree inflammation may play a central role in both diseases. Glycosylated haemoglobin A(1c) (HbA(1c)) is an established measure of long-term glycaemic control but data on its correlation with markers of inflammation are limited, especially in patients with atherosclerotic manifestations. The aim of the present study was thus to investigate the associations between HbA(1c) and a panel of inflammation-sensitive parameters in patients with and without diabetes. METHODS AND RESULTS: This single centre cross-sectional study comprised 314 consecutive subjects who underwent coronary angioplasty for stable coronary artery disease. Sixty-six patients had diabetes mellitus. Haemoglobin A(1c) and markers of inflammation, i.e., plasma levels of CRP, fibrinogen, and albumin, erythrocyte sedimentation rate and white blood cell count were measured. All inflammation markers were altered in a more inflammatory direction in diabetic patients. Furthermore, when non-diabetic patients with HbA(1c) levels within the normal range were studied separately, all inflammation-sensitive parameters except albumin correlated significantly with HbA(1c). CONCLUSION: In subjects with known coronary atherosclerosis, low-degree inflammatory activity is not only increased in diabetic patients, but also increased with increasing HbA(1c) in non-diabetic individuals with HbA(1c) within the normal range, i.e., at a pre-diabetic level of glucose metabolism derangement.

Troponin must be measured before and after PCI to diagnose procedure-related myocardial injury.

OBJECTIVE: To evaluate troponin I >99th percentile of normal as a criterion for myocardial injury after percutaneous coronary intervention (PCI). DESIGN: Troponin I and creatine kinase monobasic (CK-MB) were measured in 327 patients before and after percutaneous transluminal coronary angioplasty (PTCA) with stent implantation. RESULTS: Troponin I was elevated before PCI in 100 of a total of 222 patients with acute coronary syndrome (ACS). In 91 of these 100 patients, troponin I was elevated also after PCI but actual increases in troponin I concentrations from before to after PCI were found in only 32 patients. The increase of troponin I correlated with post-procedural CK-MB whereas post-procedural troponin I levels did not correlate. In the 122 patients with ACS but normal/normalized troponin I before PCI and in 105 patients with stable coronary artery disease post-procedural troponin I appeared to be a reliable indicator of myocardial infarction (MI), however more sensitive than CK-MB. CONCLUSION: Troponin I after PCI is sensitive to pre-procedural concentrations. To avoid false positive MI diagnoses we thus suggest that troponin I should be measured before as well as after the procedures and only actual increases should be regarded as indicating procedure-related MI.