Impact of recanalization of chronic total occlusion on left ventricular electrical remodeling

Incidence of ventricular arrhythmias in patients with chronic total coronary occlusion: Results of the VACTOR study

Background

A chronic total coronary occlusion (CTO) is associated with ventricular arrhythmias (VA) in patients with an implantable cardioverter-defibrillator (ICD). Limited data is available on the incidence of VA in CTO patients without an ICD.

Objectives

To investigate the incidence of sustained VA in CTO patients after successful CTO revascularization and in patients with untreated CTO or failed CTO revascularization.

Methods

Prospective, multicenter observational pilot study including CTO patients who were not eligible for an ICD and had a left ventricular ejection fraction >35 %. We enrolled patients with a successful CTO revascularization (group A) and patients with untreated CTO or failed CTO revascularization (group B). All patients received an implantable loop recorder with remote monitoring. The primary endpoint was sustained VA.

Results

Ninety patients were enrolled (mean age 63 ± 10 years, 83.3 % man, mean LVEF 55 ± 8 %). Group A (n = 45) had a higher prevalence of CTO in the left anterior descending artery in comparison to group B (n = 45) (28.9 % versus 4.4 %, P = 0.002). Other baseline characteristics were similar. During a median follow-up time of 26 months (IQR, 19-35), five patients (5.6 %) had a sustained VA. There was no difference in the incidence of sustained VA between groups (3-year cumulative event rate: 8.8 % (group A) versus 4.5 % (Group B), log-rank P = 0.71).

Conclusion

Patients with an CTO, who do not qualify for an ICD, have a substantial risk of sustained VA. In our study the incidence was not different between patients with revascularized and those with untreated CTO.

Non-revascularized chronic total occlusions impact on substrate and post-ablation results in drug-refractory electrical storm

Background and aims

There is limited data concerning the effect of non-revascularized chronic total occlusions (NR-CTOs) after VT ablation. This study sought to evaluate the impact of NR-CTOs after ablation for electrical storm (ES).

Methods

Post-hoc retrospective analysis of data regarding 64 consecutive post-myocardial infarction patients (out of which 12 patients with NR-CTOs and 52 without NR-CTOs) undergoing substrate ablation for ES with an available median follow-up of 37.53 (7.25-64.65) months. Ablation result was assessed by inducibility of sustained monomorphic VT (SMVT) during final programmed ventricular stimulation (PVS). The primary endpoints were all-cause mortality and VT/VF recurrences after ablation, respectively, stratified by the presence of NR-CTOs. The secondary endpoint was to assess the predictive effect of NR-CTOs on all-cause mortality and VT/VF recurrences in relation to other relevant prognostic factors.

Results

At baseline, the presence of NR-CTOs was associated with higher bipolar BZ-to-total scar ratio (72.4% ± 17.9% vs. 52% ± 37.7%, p = 0.022) and more failure to eliminate the clinical VT (25% (3) vs. 0% (0), p < 0.001). During follow-up, overall all-cause mortality and recurrences were more frequent in the NR-CTO subgroup (75% (9) vs. 19.2% (10), log rank p = 0.003 and 58.3% vs. 23.1% (12), log rank p = 0.042 respectively). After adjusting for end-procedural residual SMVT inducibility, NR-CTOs predicted death during follow-up (HR 3.380, p = 0.009) however not recurrence (HR 1.986, p = 0.154).

Conclusions

NR-CTO patients treated by RFCA for drug-refractory ES demonstrated a higher ratio of BZ-to-total-scar area. In this analysis, NR-CTO was associated with worse acute procedural results and may as well impact long-term outcomes which should be further assessed in larger patient populations.

Improved prediction of electrical storm in patients with prior myocardial infarction and implantable cardioverter defibrillator

AIMS

To evaluate predictors of electrical storm (ES), including chronic total occlusion in an infarct-related coronary artery (infarct-related artery CTO, IRACTO), in a cohort of patients with prior myocardial infarction (MI) and implantable cardioverter-defibrillators (ICD).

METHODS

Multicenter observational cohort study including 643 consecutive patients with prior MI and a first ICD implanted between 2005 and 2018 at three tertiary hospitals. All the patients included in the study had undergone a diagnostic coronary angiography before ICD implantation. The variable prior ventricular arrhythmias (VA+) was positive in patients with secondary prevention ICDs and in those with at least one appropriate ICD therapy after primary prevention implantation.

RESULTS

During a median follow-up of 42 months 59 patients (9%) suffered ES. The presence of at least one IRACTO not revascularized (IRACTO-NR) was associated with a significantly higher cumulative incidence of ES (14.5% vs 4.8%, p < 0.001). IRACTO-NR maintained a significant association with ES after adjustment for potential confounders (HR 2.3, p = 0.005) and was an independent predictor of ES together with VA+ and LVEF. The best cut-off of LVEF to predict ES was ≤38%. A risk-prediction model based on IRACTO-NR, VA+ and LVEF≤38% identified three categories of ES risk (low, intermediate and high), with progressively increasing cumulative incidence of ES (2.2%, 9% and 20%).

CONCLUSION

In a cohort of patients with prior MI and ICD, IRACTO-NR is an independent predictor of ES. A new risk-prediction model allowed the identification of three categories of risk, with potentially important clinical implications.

Vulnerability for ventricular arrhythmias in patients with chronic coronary total occlusion

INTRODUCTION

The presence of a chronic total occlusion (CTO) is associated with an increased risk of ventricular arrhythmias.

AREAS COVERED

This review provides an overview of the relationship between CTO and ventricular arrhythmias, arrhythmogenic mechanisms, and the effect of revascularization.

EXPERT OPINION

Studies in recipients of an implantable cardioverter-defibrillator (ICD) have shown that a CTO is an independent predictor of appropriate ICD therapy. The myocardial territory supplied by a CTO is a pro-arrhythmogenic milieu characterized by scar tissue, large scar border zone, hibernating myocardium, residual ischemia despite collaterals, areas of slow conduction, and heterogeneity in repolarization. Restoring coronary flow by revascularization might be associated with electrical homogenization as reflected by a decrease in QT(c) dispersion, decrease in T wave peak-to-end interval, reduction of late potentials, and decrease in scar border zone area. Future research should explore whether CTO revascularization results in a lower burden of ventricular arrhythmias. Furthermore, risk stratification of CTO patients without severe LV dysfunction is interesting to identify potential ICD candidates. Potential tools for risk stratification are the use of electrocardiographic parameters, body surface mapping, electrophysiological study, and close rhythm monitoring using an insertable cardiac monitor.

Impact of recanalization of chronic total occlusion on left ventricular electrical remodeling

Background

Successful percutaneous coronary intervention (PCI) for chronic total occlusion (CTO) is associated with reduction of cardiac mortality, as well as reducing fatal ventricular arrhythmias. The aim of this study was to evaluate the effect of recanalization of CTO on endocardial left ventricular voltages by paired electrophysiological studies.

Methods

Sixteen consecutive patients who underwent PCI for de novo CTO lesions were included. High‐density mapping was performed during sinus rhythm before and 8 months after PCI. According to the amplitude of bipolar electrograms, the left ventricular endocardium was classified into a preserved normal voltage (>1.5 mV), border zone (0.5–1.5 mV), and dense scar areas (<0.5 mV).

Results

The border zone area had a significant positive correlation with CTO length, as well as a significant negative correlation observed in the preserved voltage region. In the successful PCI patient, the median dense scar area did not change significantly (reported as [median difference: 95% confidence interval]) between baseline and after PCI (0.1 cm²: –2.8 to 2.9). However, the area of the border zone decreased (–10.5 cm²: –16.8 to –4.1) and the preserved voltage area increased significantly (19.2 cm²: 7.7–30.6). In addition, successful PCI was related to slight, but significant, increase in the amplitude of unipolar and bipolar voltage (1.55 mV: 0.88–3.33, 0.23 mV: 0.08–0.36).

Conclusions

Recanalization of CTO may promote reverse electrical remodeling in the border zone of the left ventricle, without affecting the dense scar tissue.