The effect of revascularization of a chronic total coronary occlusion on electrocardiographic variables. A sub-study of the EXPLORE trial.

INTRODUCTION: Chronic total coronary occlusions (CTOs) have been associated with a higher prevalence of ventricular arrhythmias compared to patients without a CTO. We evaluated the effect of CTO revascularization on electrocardiographic (ECG) variables. METHODS: We studied a selection of ST-elevation myocardial infarction patients with a concomitant CTO enrolled in the EXPLORE trial. ECG variables and cardiac function were analysed at baseline and at 4 months follow-up. RESULTS: Patients were randomized to percutaneous coronary intervention (PCI) of their CTO (n = 77) or to no-CTO PCI (n = 81). At follow-up, median QT dispersion was significantly lower in the CTO PCI group compared to the no-CTO PCI group (46 ms [33-58] vs. 54 ms [37-68], P = 0.043). No independent association was observed between ECG variables and cardiac function. CONCLUSION: Revascularization of a CTO after STEMI significantly shortened QT dispersion at 4 months follow-up. These findings support the hypothesis that CTO revascularization reduces the pro-arrhythmic substrate in CTO patients.

Value of the SYNTAX Score in ST-Elevation Myocardial Infarction Patients With a Concomitant Chronic Total Coronary Occlusion(from the EXPLORE Trial).

`To analyze the impact of additional coronary artery disease, quantified by the SYNTAX (SYNergy between PCI with TAXus and cardiac surgery) score, on left ventricular ejection fraction (LVEF) and long-term outcomes in a cohort of ST-elevated myocardial infarction (STEMI) patients with a concomitant chronic total coronary occlusion (CTO). A total of 302 STEMI patients were randomized to percutaneous coronary intervention of a CTO (CTO PCI) (n = 148) or conservative CTO treatment (n = 154). SYNTAX scores were calculated by an independent corelab (Cardialysis BV, Rotterdam) at two time-points: (1) at baseline, and (2) after primary PCI in the conservative CTO arm and after CTO PCI in the invasive arm (named 'discharge SYNTAX score'). The population was divided in two groups (below or equal to the median SYNTAX score preprimary PCI, or above the median). At 4-month follow-up, the LVEF was significantly lower in patients in the group with a SYNTAX score above the group median (42.8% vs 48.5%, p = 0.001), and the SYNTAX score was an independent predictor for LVEF at 4 months (ß-0.151 (SE 0.068), p = 0.028). In the group with a SYNTAX score above the group median the mortality rate was higher (10.1% vs 3.9%, p = 0.025), and there was a trend towards a higher MACE rate (15.4% vs 8.5%, p = 0.063). In conclusion, in this sub-analysis of the EXPLORE trial we observed a worse LVEF and a higher mortality rate for patients with a SYNTAX score above the median. We found that the SYNTAX score is an independent negative predictor for LVEF and an independent positive predictor for LVEDV at 4-month follow-up.

Impact of collateralisation to a concomitant chronic total occlusion in patients with ST-elevation myocardial infarction: a subanalysis of the EXPLORE randomised controlled trial.

Objective: The impact on cardiac function of collaterals towards a concomitant chronic total coronary occlusion (CTO) in patients with ST-elevation myocardial infarction (STEMI) has not been investigated yet. Therefore, we have evaluated the impact of well-developed collaterals compared with poorly developed collaterals to a concomitant CTO in STEMI. Methods and results: In the EXPLORE trial, patients with STEMI and a concomitant CTO were randomised to either CTO percutaneous coronary intervention (PCI) or no-CTO PCI. Collateral grades were scored angiographically using the Rentrop grade classification. Left ventricular ejection fraction (LVEF) and left ventricular end-diastolic volume (LVEDV) at 4 months were measured using cardiac magnetic resonance imaging. Well-developed collaterals (Rentrop grades 2-3) to the CTO were present in 162 (54%) patients; these patients had a significantly higher LVEF at 4 months (46.2±11.4% vs 42.1±12.7%, p=0.004) as well as a trend for a lower LVEDV (208.2±55.7 mL vs 222.6±68.5 mL, p=0.054) when compared with patients with poorly developed collaterals to the CTO. There was no significant difference in the total amount of scar in the two groups. Event rates were statistically comparable between patients with well-developed collaterals and poorly developed collaterals to the CTO at long-term follow-up. Conclusions: In patients with STEMI and a concomitant CTO, the presence of well-developed collaterals to a concomitant CTO is associated with a better LVEF at 4 months. However, this effect on LVEF did not translate into improvement in clinical outcome. Therefore, the presence of well-developed collaterals is important, but should not solely guide in the clinical decision-making process regarding any additional revascularisation of a concomitant CTO in patients with STEMI. Clinical trial registration: NTR1108.

The relationship between the number of preprocedural circulating endothelial progenitor cells and angiographic restenosis following coronary artery stent placement.

OBJECTIVE: In animals, endothelial progenitor cells (EPCs) beneficially influence the repair of the coronary vessel wall after damage by stent placement. However, their role in humans is less well understood. In the present study, the authors aimed to evaluate the relationship between the number of preprocedural EPCs defined as CD34+/KDR+/CD133+ cells and angiographic late loss as a measure of the growth of in-stent intimal hyperplasia. DESIGN SETTING PATIENTS AND INTERVENTIONS: The 59 study patients were treated in the authors' clinic with a Genous EPC capturing stent, a bare metal stent (BMS) or a drug-eluting stent, and angiographic follow-up occurred between 6 and 13 months. RESULTS: The authors found no relationship between preprocedural EPCs and angiographic late loss, irrespective of stent type. Though statistically not significant, patients with a high number of preprocedural CD34 cells and treated with a Genous stent or BMS showed a numerically higher late loss (in Genous patients: 1.03±0.76 mm vs 0.71±0.50 mm, p=0.15; in BMS patients: 1.06±0.73 mm vs 0.35±0.62 mm, p=0.08). CONCLUSIONS: Considering these and other varied observations, further studies aimed at identifying the biological mechanism and the individual roles of EPCs and/or CD34 cells in endothelial repair after coronary vessel stenting are needed.