Background-Collaterals can maintain myocardial function or preserve viability in chronic total coronary occlusions (CTOs). It is unknown whether and to what extent collaterals regress after successful recanalization of a CTO. Methods and Results-In 103 patients with successful recanalization of a CTO collateral function was assessed by intracoronary Doppler and pressure recordings before and after recanalization, and again after 5.0Ϯ1.3 months. Doppler (CFI) and pressure-derived collateral function indexes (CPI) and collateral (R Coll ) and peripheral resistance indexes (R P ) were calculated. In 10 patients with reocclusion, all without myocardial infarction during follow-up, collateral function had reached a similar level as before the first recanalization. In the other 93 patients with or without restenosis, collateral function was attenuated during follow-up. CPI had decreased by 23% immediately after recanalization (PϽ0.001) and decreased further by another 23% at follow-up (PϽ0.001). The R Coll increased immediately after recanalization by 82% (PϽ0.001) and by a further 273% at follow-up (PϽ0.001). In contrast, R P increased only by 22% after recanalization (PϽ0.001) and by an additional 12% at follow-up (PϽ0.05). The initial size of the collaterals but not the incidence of a restenosis influenced the collateral regression. Only 18% of patients at follow-up had collaterals with a CPI Ͼ0.30, presumably sufficient to prevent ischemia during acute occlusion. Conclusions-Collateral function regresses during long-term follow-up, especially in collaterals with a small diameter. In the majority of patients, collaterals are not readily recruitable in the case of acute occlusion. However, collaterals have the potential to recover in the case of chronic reocclusion.
Objective: To assess the potential for recovery of impaired microvascular function in collateral dependent myocardium after recanalisation of a chronic total coronary occlusion and the determinants of this recovery. Patients and design: 120 patients underwent a successful recanalisation of a chronic total coronary occlusion (duration . 2 weeks) and a follow up angiography after a mean (SD) of 5.0 (1.2) months. The coronary flow velocity reserve (CFVR) and the fractional flow reserve were measured after recanalisation and at follow up. Global and regional left ventricular (LV) function were analysed by quantitative angiography. Results: Microvascular dysfunction, defined by a CFVR , 2.0 and a fractional flow reserve > 0.75, was observed in 55 (46%) patients after recanalisation. Microvascular function improved during follow up in 24 (20%). The CFVR increased during follow up from 2.01 (0.58) to 2.50 (0.79) (p , 0.001), due to a decrease in basal average peak velocity from 30.7 (14.9) cm/s to 25.5 (13.3) cm/s (p = 0.001). Improved microvascular function was associated with an improved regional LV function, shown by a correlation between increased wall motion severity index and increased CFVR (r = 0.38, p = 0.003). The major determinant of microvascular dysfunction at baseline was the presence of diabetes mellitus (odds ratio 4.3, 95% confidence interval 1.8 to 10.2), which remained so at follow up (odds ratio 4.1, 95% confidence interval 1.3 to 13.4). Improvement of LV function was not impaired by the presence of microvascular dysfunction after recanalisation. Conclusions: The frequently observed microvascular dysfunction after recanalisation of a chronic total coronary occlusion is a transient phenomenon in most patients and is influenced by the presence of diabetes mellitus. It does not impede the recovery of LV function. Improved regional LV function is associated with improved microvascular function.T he rationale for the recanalisation of a chronic total coronary occlusion is the possible improvement of left ventricular (LV) function through the recovery of hibernating myocardium.
This study showed that there is no relation between a well-developed collateral supply and the risk of TVF in recanalized CTOs. This was rather determined by the stented segment length. There was also no adverse effect of the frequently observed impaired CFVR on TVF, whereas a low FFR was associated with a higher risk of reocclusion.
The efficacy and safety of CCM in this study were similar when the signal was delivered through either one or two ventricular leads. These results support the potential use of a single ventricular lead for delivery of CCM.
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