Gero Schwarz

Regression of collateral function after recanalization of chronic total coronary occlusions: A serial assessment by intracoronary pressure and Doppler recordings

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 5.0±1.3 months. Doppler (CFI) and pressure-derived collateral function indexes (CPI) and collateral (RColl) and peripheral resistance indexes (RP) 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 (P <0.001) and decreased further by another 23% at follow-up (P <0.001). The RColl increased immediately after recanalization by 82% (P <0.001) and by a further 273% at follow-up (P <0.001). In contrast, RP increased only by 22% after recanalization (P <0.001) and by an additional 12% at follow-up (P <0.05). 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 >0.30, 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.

Paclitaxel-eluting stents for the treatment of chronic total coronary occlusions: A strategy of extensive lesion coverage with drug-eluting stents

The recanalization of a chronic total coronary occlusion (CTO) is hampered by a high rate of lesion recurrence. The goal of the present study is to assess the effect of paclitaxel‐eluting stents in CTOs in a strategy of extensive stent coverage and the optional use of additional bare metal stents (BMSs). In 82 consecutive patients, a CTO (duration > 2 weeks) was successfully recanalized with implantation of one or more Taxus stents. These patients underwent a repeat angiography after 5.0 ± 1.5 months and were assessed by quantitative angiography. The patients were compared with 82 clinically and lesion‐matched patients from a consecutive series of 148 patients with CTOs treated by BMS in the preceding time period. In 21 of the 82 patients, additional lesions in the target artery not directly related to the original occlusion site were treated with BMSs (hybrid approach). The history of diabetes, extent of coronary artery disease, clinical symptoms, and angiographic features were similar in the Taxus and BMS group. Periprocedural adverse events were 3.3% with Taxus and 3.3% with BMS, but 12 months MACE was significantly lower in the group with exclusive use of Taxus (13.3% vs. 56.7%; P < 0.001), mainly due to a lower target lesion revascularization of 10.0% as compared to 53.4% (P < 0.001). There was only one late reocclusion with Taxus (1.7%) as compared to 21.7% with BMS (P < 0.05). However, in the hybrid group, the MACE rate was considerably higher, with 33.3%. Our data of a 80% reduction of target vessel failure as compared to BMS, with a lower risk of late reocclusions without increased acute adverse events, demonstrate the benefit of paclitaxel‐eluting stents in CTOs. However, diffuse atherosclerosis in CTOs should be covered completely by the drug‐eluting stents.

Reproducibility of HTS-SQUID magnetocardiography in an unshielded clinical environment

A new technology has been developed which measures the magnetic field of the human heart (magnetocardiogram, MCG) by using high temperature superconducting (HTS) sensors. These sensors can be operated at the temperature of liquid nitrogen without electromagnetic shielding. We tested the reproducibility of HTS-MCG measurements in healthy volunteers. Unshielded HTS-MCG measurements were performed in 18 healthy volunteers in left precordial position in two separate sessions in a clinical environment. The heart cycles of 10 min were averaged, smoothed, the baselines were adjusted, and the data were standardized to the respective areas under the curves (AUC) of the absolute values of the QRST amplitudes. The QRS complexes and the ST-T intervals were used to assess the reproducibility of the two measurements. Ratios (R(QRS), R(STT)) were calculated by dividing the AUC of the first measurement by the ones of the second measurement. The linear correlation coefficients (CORR(QRS), CORR(STT)) of the time intervals of the two measurements were calculated, too. The HTS-MCG signal was completely concealed by the high noise level in the raw data. The averaging and smoothing algorithms unmasked the QRS complex and the ST segment. A high reproducibility was found for the QRS complex (R(QRS)=1.2+/-0.3, CORR(QRS)=0.96+/-0.06). Similarly to the shape of the ECG it was characterized by three bends, the Q, R, and S waves. In the ST-T interval, the reproducibility was considerably lower (R(STT)=0.9+/-0.2, CORR(STT)=0.66+/-0.28). In contrast to the shape of the ECG, a baseline deflection after the T wave which may belong to U wave activity was found in a number of volunteers. HTS-MCG devices can be operated in a clinical environment without shielding. Whereas the reproducibility was found to be high for the depolarization interval, it was considerably lower for the ST segment and for the T wave. Therefore, before clinically applying HTS-MCG systems to the detection of repolarization abnormalities in acute coronary syndromes, further technical development of the systems is necessary to improve the signal-to-noise ratio.

Improvement of the primary success rate of recanalization of chronic total coronary occlusions with the Safe-Cross system after failed conventional wire attempts

BackgroundIn view of the improved long-term patency with drug-eluting stents, the challenge with chronic total coronary occlusion (CTO) remains the low primary success rate. Improved guide wires have increased this rate, but alternative devices may be of additional value. The goal of the present study was to determine the additional benefit of a new penetration device in CTOs after an extensive conventional wire approach.Methods and ResultsIn 148 consecutive patients the recanalization of a CTO of >3 months was attempted. A conventional wire approach was used with recent dedicated recanalization wires, which was successful in 104 patients (70%). If after at least 20 min of fluoroscopic time no crossing of the wire was achieved, the Safe-Cross wire (SC) (Intralumina) was used which enables verification of the intraluminal wire position via optical reflectometry, and crossing of resistent occlusion caps by radiofrequency ablation. Due to severe dissections after the conventional approach, the SC was not used in 10 patients. In 34 patients the SC wire was applied, leading to successful lesion crossing in 14 patients (41%). Thus, the primary success rate was improved from 70.2% to 79.7%. No periprocedural major adverse events were observed with the SC wire. The successful attempts with the SC wire were predominantly in blunt occlusions. All patients with successful wire passage could be treated with one or more stents.ConclusionsIn a real world cohort of patients with CTO, the SC wire could increase the primary success rate after failed extensive conventional wire attempt. In these worst case patients the SC success rate was 41%. This new wire appears to have additional potential in failures of a conventional wire approach.

Sirolimus-eluting stents for the prevention of restenosis in a worst-case scenario of diffuse and recurrent in-stent restenosis

For recurrent in‐stent restenosis (ISR), surgical revascularization or brachytherapy is still the principal therapeutic options. The present investigation explores the efficacy of a sirolimus‐eluting stent to prevent restenosis in these lesions with a high risk of recurrence. In 22 consecutive patients with a recurrent and diffuse ISR, a sirolimus‐eluting stent was implanted to cover the restenotic lesion. All patients were followed clinically for at least 1 year and underwent a repeat angiography after 7 months. A quantitative coronary angiographic analysis was done. The target vessel failure was 14% in the sirolimus‐eluting stent group, with an angiographic late loss of only 0.39 ± 0.54. No subacute stent thrombosis was observed, and the 1‐year event‐free survival was 86%. The three cases with restenosis were all focal and could be successfully treated by additional drug‐eluting stent implantation. This study showed the efficacy of a sirolimus‐eluting stent for the prevention of restenosis in a worst‐case scenario of recurrent and diffuse ISR. The observed restenosis rate is lower than that reported after brachytherapy and suggests that sirolimus‐eluting stents are a promising treatment option for ISR. Catheter Cardiovasc Interv 2004;63:259–264.

1080-42 Resting 12-lead electrocardiogram as a reliable predictor of functional recovery after recanalization of chronic total coronary occlusions

BACKGROUND A major goal of revascularization is the recovery of left ventricular (LV) function. Nuclear imaging techniques are widely used for detecting recovery of function with a good sensitivity, but only moderate specificity. Predictors of recovery in chronic total coronary occlusions (CTO) are not investigated. HYPOTHESIS The 12-lead-resting electrocardiogram (ECG) is a predictor of LV recovery after successful recanalization of CTO. METHODS Successful recanalization of CTO was performed in 127 patients. Of these, 62 patients, who constitute the study group, had impaired regional wall motion prior to recanalization. The 12-lead resting ECG was evaluated for Q-wave areas and parameters of QT dispersion. Impairment of regional wall motion was evaluated by LV angiogram at baseline and at follow-up. RESULTS Angiographic follow-up after 5 +/- 1.4 months documented reocclusion in eight patients. Complete follow-up with a patent coronary artery and an ECG without bundle-branch block was available in 43 patients. Wall motion severity index (WMSI) improved from -2.92 +/- 0.28 to -1.34 +/- 0.61 (p < 0.001) in patients without Q waves, whereas it was unchanged in patients with Q waves (-3.01 +/- 0.30 and -2.81 +/- 0.32). Absence of Q waves at baseline predicted recovery of regional wall motion with 89% sensitivity and 67% specificity. Positive predictive value for recovery was 68% in patients without Q waves, but only 11% in patients with Q waves. In multivariate analysis, only absence of Q waves predicted improvement in WMSI (p = 0.01). CONCLUSIONS In patients with recanalization of CTO, recovery of regional wall motion is reliably predicted by analysis of the resting 12-lead ECG for pathologic Q waves.

HIGH RESOLUTION DC MCG MEASUREMENTS OF U WAVE ACTIVITY IN HEALTHY VOLUNTEERS

The circulation is driven by the rhythmical heart beating. The mechanic heart cycle is clearly divided into contraction and relaxation. More difficult is the division of the heart cycle into electric activity and the absence of electric activity. In electrocardiograms the duration of the electric heart cycle can be assessed manually or with the help of dedicated computer algorithms. However, sufficiently exact measures are impaired by a number of problems, particularly with regard to the U waves and slight baseline fluctuations shortly after the T wave. Comprehensive studies have demonstrated a considerable inter-observer and intraobscrver variability for expert cardiologists and discordant results of computer algorithms, too (see e.g. [1]). Essential reasons for these discrepancies were the different assignments of morphological T wave categories as well as different criteria for separating the T and U waves. The distinction between the U wave and the T wave will become particularly difficult, if the T wave is notched or prolonged. Two approaches may help to solve these problems. First, electrophysiological processes of different quality generate different spatial signal patterns on the body surface. Therefore, the separation of the T wave from the U wave will be improved by comparing spatial patterns of heart signals. Second, the assessment of heart activity means measuring an activity above a certain noise level caused by the measurement device. Supposing that the noise level of the device is very low and exactly known, the signal can be traced to the very end until it is below this noise level. It is the purpose of this study to apply the signal averaged DC magnetocardiography (DC MCG) to a representative number of volunteers and to measure the duration of the electric heart cycle.