Upregulation of CD40/CD40L system in rheumatic mitral stenosis with or without atrial fibrillation

Association of platelet activation markers with recurrence of atrial fibrillation after pulmonary vein isolation

Atrial fibrillation (AF) is known to cause platelet activation. AF and its degree of thrombogenesis could be associated with monocyte-platelet aggregates (MPAs). We investigated on whether the content of MPAs or other platelet activation markers is associated with the recurrence of AF after pulmonary vein isolation (PVI). A total of 73 patients with symptomatic AF underwent PVI. After 6 months, all patients were evaluated for episodes of AF recurrence. At the same time, flow-cytometric quantification analyses were performed to determine the content of MPAs. Further platelet activation parameters were detected by using either cytometric bead arrays or quantitative immunological determination. Patients with recurrent AF (n = 20) compared to individuals without AF relapse (n = 53) were associated with an increased content of MPAs (43 ± 3% vs. 33 ± 2%, p = 0.004), as well as an increased CD41 expression on monocytes (191 ± 20 vs. 113 ± 6, p = 0.001). The level of the soluble platelet activation markers such as D-dimer, sCD40L, and sP-selectin did not differ between these groups. The content of MPAs correlated weakly with the level of sCD40L (r = 0.26, p = 0.03), but not with sP-selectin and D-dimer, whereas sP-selectin and sCD40L correlated with each other (r = 0.38, p = 0.001). Only the cellular marker of platelet activation, the content of MPAs, was increased in patients with recurrent AF after PVI. In contrast, soluble markers remained unaltered. These data indicate a distinct mechanism and level of platelet activation in AF. The clinical relevance of MPAs in identifying AF recurrence or in guiding the therapy with anticoagulants remains to be elucidated.

Elevated fibrinogen and lowered homocysteine-vitamin determinants and their association with left atrial thrombus in patients with rheumatic mitral stenosis

Mitral stenosis (MS) causes stagnation of blood flow, leading to thrombus formation in the left atrium (LA), which may lead to systemic thrombo-embolic complications and stroke. We compared the alterations in echocardiographic and procoagulant parameters in patients with severe rheumatic MS with and without LA thrombus. The study was a cross-sectional study of patients with rheumatic MS, being evaluated for percutaneous mitral commisurotomy. Group 1 patients comprised of patients with rheumatic MS with LA thrombus (n=35) and Group 2 patients had rheumatic MS without LA thrombus (n = 45). Platelet aggregability, fibrinogen, homocysteine, vitamin B12 and folate; mitral valve area (MVA), mean mitral gradient and pulmonary artery pressure (PAP) were assessed in all study subjects. Significant increase in fibrinogen, homocysteine and platelet aggregation and fall in homocysteine-associated determinants were seen in Group 1, as compared with Group 2. Raised fibrinogen, lowered homocysteine-vitamin determinants and lowered mitral valve area were associated independently, with presence of LA thrombus in rheumatic MS. In this study, fibrinogen, vitamin B12 and folate were independently associated with the occurrence of thrombus in patients with rheumatic MS. Hence, our results suggest that increase in procoagulant mechanisms contribute to increased risk of thrombosis in the left atrium in patients with rheumatic MS.

Circulating Endothelial Cells and Platelet Microparticles in Mitral Valve Disease With and Without Atrial Fibrillation

Hypercoagulability in mitral valve disease (MVD), a cause of atrial fibrillation (AF) and stroke, is potentially due to endothelial damage/dysfunction (marked by circulating endothelial cells [CECs]), platelet activation (soluble P-selectin [sPsel], platelet microparticles [PMPs], and soluble CD40 [sCD40]), and oxidized low-density lipoprotein (oxLDL) cholesterol. We measured these variables in 24 patients with MVD as well as in 21 with MVD + AF and compared them with 20 healthy controls (HCs). The CECs and PMPs were measured by flow cytometry; sPsel, oxLDL, and CD40 by enzyme-linked immunosorbent assay. Compared with HCs, sPsel and PMPs were equally higher in MVD and MVD + AF; sCD40 and oxLDL were higher in MVD + AF than in HCs and MVD; and CECs were higher in MVD than in the HCs, with further increases in MVD + AF (all P < .001). We conclude that excess platelet activation is present in MVD regardless of AF, and that increased endothelial damage in MVD is greater when compounded by AF.

Efficiency of radiofrequency ablation for surgical treatment of chronic atrial fibrillation in rheumatic valvular disease

BACKGROUND

It remains unclear whether concomitant radiofrequency ablation procedure in valvular surgery could offer additional benefits to patients with rheumatic valvular disease. We designed a prospective and randomized control study to evaluate the efficacy of surgical radiofrequency ablation in patients with rheumatic heart disease.

METHODS

From June 2008 to July 2011, 210 patients with chronic atrial fibrillation and rheumatic heart disease were randomized: (1) control group, patients underwent only valve replacement followed by amiodarone for rhythm control, (2) left atrial group (LA group), patients underwent valve replacement and left atrial mono-polar radiofrequency ablation, (3) bi-atrial group (BA group), patients underwent valve replacement and bi-atrial mono-polar radiofrequency ablation. The primary endpoints included: cardiac death, stroke, and recurrent AF after discharge.

RESULTS

There was no perioperative death. One patient died 4 months after MVR in BA group. In univariate Cox analysis, the two ablation groups were associated with less AF (BA group vs control group: P<0.001; LA group vs control group: P<0.001) as well as atrial tachycardia arrhythmia (AF/AT/AFL) recurrent (BA group vs control group: P<0.001; LA group vs control group: P=0.02). The comparison between BA and LA groups revealed no differences in terms of AF (P=0.06) or AF/AT/AFL (P=0.09). Atrial transport function restoration rate 12 months after operation was 31.4% in LA group, 32.9% in BA group, and 8.6% in control group respectively (P<0.01).

CONCLUSIONS

Radiofrequency ablation concurring with valvular surgery can bring a higher sinus rhythm restoration rate when compared with medical anti-arrhythmic drug therapy in low-medium risk rheumatic heart disease. The trial was registered on Clinicaltrials.gov (registry number NCT01013688).