Cardiac rehabilitation programme as a non-pharmacological platelet inhibitory tool in acute coronary syndrome survivors.

Background Acute coronary syndrome is associated with platelet hyperactivity, which in its persistent form, promotes recurrent thrombotic events. Complex cardiac rehabilitation after acute coronary syndrome improves clinical outcome; however, its effect on platelet hyperactivity is unknown. Design and methods We enrolled 84 acute coronary syndrome patients on dual antiplatelet therapy, who underwent a new complex cardiac rehabilitation programme (NovaCord physiotherapy, lifestyle counselling, strict diet, stress management and regular coaching) and 51 control acute coronary syndrome patients with traditional cardiac rehabilitation. Platelet functionality was determined at enrolment and at three months follow-up by aggregometry, serum platelet-derived growth factor levels, total- and platelet-derived microvesicle counts (PMV; CD41a+/CD61+, CD62P+). Results Platelet aggregation parameters and platelet-derived growth factor levels were significantly decreased in the complex cardiac rehabilitation group at three months (1 µg/ml collagen, median (interquartile range): 22 (10-45) vs 14 (7.5-25.5)%, p = 0.0015; 2 µg/ml collagen: 36 (22-60) vs 26.5 (16-37)%, p = 0.0019; 1.25 µM adenosine-diphosphate: 4.5 (1-10) vs 1 (0-3)%, p = 0.0006; 5 µM adenosine-diphosphate: 27 (16-38) vs 22 (12-31)%, p = 0.0078; epinephrine: 33 (15-57) vs 27 (12-43)%, p = 0.01; platelet-derived growth factor: 434.6 (256.0-622.7) vs 224.8 (148.5-374.1) pg/ml, p = 0.0001). In contrast, these changes were absent or did not reach statistical significance in the traditional cardiac rehabilitation group. Platelet-derived microvesicle counts were significantly decreased in both groups, while total microvesicle count was significantly reduced only in the complex cardiac rehabilitation group (median (interquartile range): 3945.5 (2138-5661) vs 1739 (780-2303) count/µl; p = 0.0001). Conclusions Platelet hyperactivity three months after acute coronary syndrome significantly decreased in patients undergoing complex cardiac rehabilitation. Besides dual antiplatelet therapy, effective management and comprehensive control of cardiovascular risk factors might represent a new, non-pharmacological approach to influence platelet functionality.

Alternative complement pathway activation during invasive coronary procedures in acute myocardial infarction and stable angina pectoris.

The effect of invasive percutaneous coronary procedures on complement activation has not been elucidated. We enrolled stable angina patients with elective percutaneous coronary intervention (SA-PCI, n=24), diagnostic coronary angiography (CA, n=52) and 23 patients with ST segment elevation myocardial infarction and primary PCI (STEMI-PCI). Complement activation products (C1rC1sC1inh, C3bBbP and SC5b-9) were measured on admission, 6 and 24h after coronary procedures. The alternative pathway product, C3bBbP significantly and reversibly increased 6h after elective PCI (baseline: 7.81AU/ml, 6h: 16.09AU/ml, 24h: 4.27AU/ml, p<0.01, n=23) and diagnostic angiography (baseline: 6.13AU/ml, 6h: 12.08AU/ml, 24h: 5.4AU/ml, p<0.01, n=52). Six hour C3bBbP values correlated with post-procedural CK, creatinine level and the applied contrast material volume (r=0.41, r=0.4, r=0.3, p<0.05, respectively). In STEMI-PCI, baseline C3bBbP level was higher, compared to SA-PCI or CA patients (11.33AU/ml vs. 7.81AU/ml or 6.13AU/ml, p<0.001). Similarly, the terminal complex (SC5b-9) level was already elevated at baseline compared to SA-PCI group (3.49AU/ml vs. 1.87AU/ml, p=0.011). Complement pathway products did not increase further after primary PCI. Elective coronary procedures induced transient alternative complement pathway activation, influenced by the applied contrast volume. In STEMI, the alternative complement pathway is promptly activated during the atherothrombotic event and PCI itself had no further detectable effect.

The lack of aspirin resistance in patients with coronary artery disease.

BACKGROUND: Aspirin resistance established by different laboratory methods is still a debated problem. Using COX1 specific methods no aspirin resistance was detected among healthy volunteers. Here we tested the effect of chronic aspirin treatment on platelets from patients with stable coronary artery disease. The expression of COX2 mRNA in platelets and its influences on the effect of aspirin was also investigated. METHODS: One hundred and forty four patients were enrolled in the study. The direct measurement of COX1 acetylation was carried out by monoclonal antibodies specific to acetylated and non-acetylated COX1 (acCOX1 and nacCOX1) using Western blotting technique. Arachidonic acid (AA) induced TXB2 production by platelets was measured by competitive immunoassay. AA induced platelet aggregation, ATP secretion and VerifyNow Aspirin Assay were also performed. COX2 and COX1 mRNA expression in platelets were measured in 56 patients by RT-qPCR. RESULTS: In 138 patients only acCOX1 was detected, in the remaining six patients nacCOX1 disappeared after a compliance period. AA induced TXB2 production by platelets was very low in all patients including the 6 patients after compliance. AA induced platelet aggregation, secretion and with a few exceptions the VerifyNow Assay also demonstrated the effect of aspirin. Smoking, diabetes mellitus and inflammatory conditions did not influence the results. The very low amount of COX2 mRNA detected in 39 % of the investigated platelets did not influence the effect of aspirin. CONCLUSIONS: No aspirin resistance was detected among patients with stable coronary artery disease. COX2 expression in platelets did not influence the effect of aspirin.

Predictors of high on-clopidogrel platelet reactivity in patients with acute coronary syndrome.

High on-clopidogrel platelet reactivity (HPR) is a predictor of ischemic events after percutaneous coronary intervention. We conducted a prospective cohort study to identify variables related to HPR in acute coronary syndrome patients who are at high thrombotic risk. We enrolled 463 patients undergoing urgent coronary angiography. Platelet reactivity was measured 12-36 hours after 600 mg clopidogrel loading with multiple electrode aggregometry (Multiplate® analyzer, Roche, Basel, Switzerland, 6.4 µM ADP). HPR was defined by the consensus cut-off area under the curve >46 U. The rate of HPR was 16.0%. We analyzed simple clinical and laboratory parameters with backward multivariate logistic regression and identified the following predictors of HPR: platelet count (per G/L, OR: 1.0073, 95% CI: 1.0035-1.0112, p = 0.0002), CRP level (per mg/L, OR: 1.0077, 95% CI: 1.0016-1.01372, p = 0.01), and active smoking (OR: 0.51, 95% CI: 0.29-0.89, p = 0.02). We developed and internally validated a risk prediction model demonstrating moderate discriminative capacity (area-under-the-receiver operating characteristic curve = 0.67). In conclusion, we found a relatively low rate of high on-clopidogrel platelet reactivity (16.0%) even in an acute patient cohort. HPR measured by Multiplate was associated with high platelet count and CRP level on admission and was inversely related to active smoking. The model with rapidly available simple parameters might help to identify individuals at risk for HPR in the acute setting.

High on clopidogrel treatment platelet reactivity is frequent in acute and rare in elective stenting and can be functionally overcome by switch of therapy.

UNLABELLED: The benefit of adjusted antiplatelet therapy in patients with myocardial infarction after primary percutaneous coronary intervention is not well elucidated. We aimed to identify patients with high on treatment platelet reactivity and to gradually adjust antiplatelet therapy. MATERIALS AND METHODS: We enrolled 133 acute myocardial infarction and 67 stable angina patients undergoing intracoronary stenting into our study. Maximal aggregation was determined with light transmission aggregometry. Aggregation >50% induced by 5 µM ADP was indexed with high on-clopidogrel treatment platelet reactivity. In these cases 75 mg clopidogrel was doubled and control test was performed. Patients effectively inhibited with 150 mg clopidogrel were defined as clopidogrel pseudo non-responders. Patients with high platelet reactivity even on 150 mg clopidogrel were considered as clopidogrel real non-responders and were switched to ticlopidine. RESULTS: Aggregations (5ADP; p=0.046) and the ratio of real non-responders (p=0.013) were significantly higher in the myocardial infarction group. Most real non-responders were effectively treated with switch of therapy. The ratio of pseudo non-responders also tended to be higher in myocardial infarction. Platelet reactivity remained constant during follow-up; however, a new appearance of high platelet reactivity was observed at 6 and at 12 months. CONCLUSIONS: Patients with acute myocardial infarction undergoing percutaneous coronary intervention may benefit from prospective platelet function testing, because of higher platelet reactivity and much higher ratio of clopidogrel real non-response. Switch of therapy may effectively overcome clopidogrel non-response. A new appearance of high platelet reactivity with unknown clinical significance is observed in both groups among the patients on clopidogrel.

Elevated C1rC1sC1inh levels independently predict atherosclerotic coronary heart disease.

UNLABELLED: Clinical studies as well as animal models emphasized the importance of the complement system in the pathogenesis of coronary atherosclerosis and cardiovascular diseases. Our aim was to examine the extent and clinical implication of complement system activation in patients with stable atherosclerotic coronary heart disease (ACHD). Seventy-six patients with stable angina pectoris (SAP) scheduled for elective coronary angiography were enrolled into the study. Percutaneous coronary intervention (PCI) was performed in 24 patients, in 27 patients (NOPCI group) the coronary angiography showed significant stenosis and bypass surgery (CABG) or optimal medical therapy (OMT) were advised, whereas in 25 patients the coronary angiography was negative (NC group). 115 volunteers served as healthy controls (HC). In all individuals, the plasma level of several complement activation products - C1rC1sC1inh, C3bBbP and SC5b-9 - were determined on admission, strictly before the coronary angiography. In patients with angiographically proven ACHD (PCI and NOPCI groups), the baseline C1rC1sC1inh levels were significantly higher compared to NC group and HC (p<0.0001, for both comparisons). According to the multiple logistic regression analysis, high C1rC1sC1inh level proved to be an independent biomarker of coronary heart disease (p<0.026, OR: 65.3, CI: 1.628-2616.284). CONCLUSION: Activation of the classical complement pathway can be observed in angiographically proven coronary atherosclerosis. Elevated C1rC1sC1inh levels might represent an useful biomarker for coronary artery disease.