Impact of revascularization of coronary chronic total occlusion on left ventricular function and electrical stability: analysis by speckle tracking echocardiography and signal-averaged electrocardiogram

Chronic Total Occlusion Interventions in Patients with Reduced Ejection Fraction

PURPOSE OF THE REVIEW

The goal of this paper is to review the current evidence surrounding CTO PCI in patients with low EF, the most high-risk population to treat. We also present pertinent case examples and offer practical tips to increase success and lower complications when performing CTO PCI in patients with low EF.

RECENT FINDINGS

In a prospective randomized control study, greater improvement in angina frequency and quality of life, assessed by the Seattle Angina Questionnaire, was achieved by CTO PCI compared to optimal medical therapy. Furthermore, after successful CTO PCI, improvements in health status were similar in patients with both low and normal EF. CTO PCI can not only ameliorate symptoms of angina in patients with low EF but may also potentially improve EF in carefully selected populations. However, information regarding treatment of this high-risk population is lacking and large-scale studies targeting patients with severely reduced EF remain necessary.

Strain Imaging for the Early Detection of Cardiac Remodeling and Dysfunction in Primary Aldosteronism

Speckle tracking echocardiography is a novel technique to quantify cardiac function and deformation. It has been applied in a series of cardiovascular diseases for the evaluation of early cardiac impairment. We recently used this technique to investigate cardiac structure and function in patients with primary aldosteronism. Cardiac damage usually occurs earlier in patients with primary aldosteronism than those with primary hypertension, probably because aldosterone hypersecretion is more commonly observed in the former than the latter patients. In this article, we will review the imaging studies, especially with speckle tracking echocardiography, for the detection of early cardiac dysfunction in primary aldosteronism as a disease model.

Functional recovery after percutaneous revascularization of coronary chronic total occlusions: insights from cardiac magnetic resonance tissue tracking

To evaluate the effect of percutaneous coronary intervention (PCI) of coronary chronic total occlusions (CTOs) on left ventricular (LV) strain assessed using cardiac magnetic resonance (CMR) tissue tracking. In 150 patients with a CTO, longitudinal (LS), radial (RS) and circumferential shortening (CS) were determined using CMR tissue tracking before and 3 months after successful PCI. In patients with impaired LV strain at baseline, global LS (10.9 ± 2.4% vs 11.6 ± 2.8%; P = 0.006), CS (11.3 ± 2.9% vs 12.0 ± 3.5%; P = 0.002) and RS (15.8 ± 4.9% vs 17.4 ± 6.6%; P = 0.001) improved after revascularization of the CTO, albeit to a small, clinically irrelevant, extent. Strain improvement was inversely related to the extent of scar, even after correcting for baseline strain (B =  − 0.05; P = 0.008 for GLS, B =  − 0.06; P = 0.016 for GCS, B =  − 0.13; P = 0.017 for GRS). In the vascular territory of the CTO, dysfunctional segments showed minor improvement in both CS (10.8 [6.9 to 13.3] % vs 11.9 [8.1 to 15.0] %; P < 0.001) and RS (14.2 [8.4 to 18.7] % vs 16.0 [9.9 to 21.8] %; P < 0.001) after PCI. Percutaneous revascularization of CTOs does not lead to a clinically relevant improvement of LV function, even in the subgroup of patients and segments most likely to benefit from revascularization (i.e. LV dysfunction at baseline and no or limited myocardial scar).

Cardiac remodeling in middle-aged endurance athletes: relation between signal-averaged electrocardiogram and LV mass

The relationship between structural and electrical remodeling in the heart, particularly after long-standing endurance training, remains unclear. Signal-averaged electrocardiogram (SAECG) may provide a more sensitive method to evaluate cardiac remodeling than a 12-lead electrocardiogram (ECG). Accurate measures of electrical function (SAECG filtered QRS duration (fQRSd) and late potentials (LP) and left-ventricular (LV) mass (cardiac magnetic resonance, CMR) can allow an assessment of structural remodeling and QRS prolongation. Endurance athletes (45-65 yr old, >10 yr of endurance sport), screened to exclude cardiac disease, had standardized 12-lead ECG, SAECG, resting echocardiogram (ECHO), and CMR performed. SAECG fQRSd was correlated with QRS duration on the 12-lead ECG, and ECHO and CMR-derived LV mass. Participants (n = 82, 67% male, mean age: 54 ± 6 yr, mean V̇o_2max: 50 ± 7 mL/kg/min) had a CMR-derived LV mass of 118 ± 28 g/m² and a fQRSd of 112 ± 8 ms (46% had abnormal fQRSd (>114 ms), and 51% met clinical threshold for abnormal SAECG). fQRSd was positively correlated with the 12-lead ECG QRS duration (r = 0.83), ECHO-derived LV mass (r = 0.60), CMR-derived LV mass (r = 0.58) and LV end-diastolic volume (r = 0.63, P < 0.001 for all). fQRSd had higher correlations with ECHO and CMR-derived LV mass than 12-lead ECG (P < 0.0008 and P < 0.0005, respectively). In conclusion, in a healthy cohort of middle-aged endurance athletes, the SAECG is often abnormal by conventional criteria, and is correlated with structural remodeling, but CMR evaluation does not indicate pathologic structural remodeling. SAECG fQRSd is superior to the 12-lead ECG for the electrocardiographic evaluation of LV mass.NEW & NOTEWORTHY Study findings indicate that a positive correlation exists between electrical (SAECG fQRSd) and structural indices (LV mass) in middle-aged endurance athletes with normal physiological LV adaptation, in the absence of known cardiac pathology. SAECG fQRSd may also provide an alternative, superior method for identifying increased LV mass compared to other 12-lead ECG criteria.

Incidence and characteristics of ventricular tachycardia in patients after percutaneous coronary revascularization of chronic total occlusions

Objectives

This study sought to investigate the prevalence of ventricular tachycardia after percutaneous coronary intervention (PCI) of chronic total occlusion (CTO).

Background

PCI of a CTO is associated with improvement of the left ventricular ejection fraction and possibly associated with reduced mortality. However, benefits of CTO-PCI must be weighed against a higher risk of procedure-related complications. The incidence of new-onset ventricular tachycardia after a successful CTO-PCI has not been investigated so far. In this retrospective registry we seek to describe characteristics and predictors of occurrence of post-procedural ventricular tachycardias.

Methods and results

Between 2010 and 2015, 485 patients underwent successful CTO-PCI at Heart Center Leipzig. Of them, 342 had complete follow-up and were further analyzed. Ventricular tachycardias were detected in 9 (2.6%) patients. All of them were monomorphic ventricular tachycardias occurring in median 1 day (interquartile range [IQR] 0.25–4.75 days) after PCI and caused prolongation of the hospital stay. Patients with ventricular tachycardia were older, had worse left ventricular ejection fraction (mean 33.1%, SD 5.9%) and more frequently a CTO of an infarct-related artery. The target vessel was not associated with the occurrence of ventricular arrhythmias. In multivariable analysis, only impaired left ventricular systolic function was an independent predictor for procedure-related ventricular tachycardia. Mortality rates were not different between patients with or without ventricular tachycardia.

Conclusion

Ventricular tachycardia can occur early after CTO-PCI as possible reperfusion arrhythmia and poorer left ventricular ejection fraction is the only independent predictor for onset. Although the occurrence of ventricular tachycardia after CTO-PCI seems not to influence mortality, awareness of this possible complication and longer monitoring may be recommended.

Evaluation of the impact of percutaneous coronary intervention of chronic total occlusion on regional myocardial function using strain echocardiography

BACKGROUND

Successful revascularization of chronic total occlusions has been associated with potential effects on left ventricular (LV) function. Strain and strain rate are more sensitive measures of LV mechanics than LV ejection fraction (LVEF). This study was conducted to investigate the impact of revascularization of chronic total occlusion (CTO) on LV function using tissue Doppler (TDI) strain echocardiography.

RESULTS

This study included 60 patients divided into two main groups: the percutaneous coronary intervention (PCI) group including patients who had a successful PCI of CTO on left anterior descending (LAD) artery and was presented for elective PCI with symptomatic angina and/or positive functional ischemic study. They included 18 males with a mean age of 57 ± 5 years. The optimum medical treatment (OMT) group, including 30 patients, had non-revascularized CTO-LAD and was kept on OMT alone; 20 of them were males with a mean age of 58 ± 4 years. In the PCI group, there was a significant improvement in all the TDI strain parameters of the LAD territory segments. Six months after PCI, the peak systolic strain rate improved from - 0.65 ± 0.21 to 1.05 ± 0.31 1/s (p value < 0.01), the peak systolic strain improved from 6.54 ± 2.48 to 11.51 ± 3.33% ( p value < 0.001 ), and the end systolic strain improved from 7.88 ± 2.77 to 10.51 ± 3.14% (p value < 0.01 ). There was no significant improvement in the mean LVEF (60.70 ± 8.33 vs 61.91 ± 8.16% (p value = 0.6)). In the OMT group, there was no improvement in all the strain parameters and there was no change in the mean LVEF. In the PCI group, there was a significant improvement in the angina class (p value = 0.03) while, in the OMT group, there was no significant improvement (p value = 0.835).

CONCLUSIONS

Successful PCI for CTO improved regional LV myocardial function assessed by TDI strain echocardiography. This improvement was associated with improvement in the angina class.

Contemporary Evidence, Treatment Strategies, and Indications for Chronic Total Occlusion-Percutaneous Coronary Intervention

Chronic total occlusions (CTOs) are detected incidentally in ˜20% of patients undergoing coronary angiography and are often associated with significant morbidity and mortality. CTOs can manifest with worsening symptoms, reduced left ventricular function, and increased incidence of ventricular arrhythmias. Despite this, according to USA, Italian, and Japanese national registry data, only ~5–22% of CTO lesions are treated by percutaneous coronary intervention (PCI). CTO-PCI is a particularly challenging technique for this subset of lesions and has traditionally been associated with increased risks and complications compared to conventional PCI. However, increased experience, the development of novel techniques, and dedicated equipment have revolutionised CTO-PCI. USA, Italian, and Japanese registry data have shown success rates of between 85% and 90%, with diminishing complication rates when performed by experienced operators. Moreover, observational studies have suggested that there are significant benefits of using CTO-PCI, including fewer symptoms, improved quality of life, reduced need for coronary artery bypass surgery, and reduction in ischaemic burden and mortality. In addition, when there is demonstrable ischaemia and viable myocardium in the CTO territory, there is further potential prognostic benefit from complete revascularisation. However, there has so far been a relative lack of randomised trial data to support the routine use of CTO-PCI. This paper reviews the current evidence surrounding this subject and discusses the arguments for and against CTO-PCI. It includes an exploration of the interventionalist’s ‘toolbox’ and the techniques used in CTO-PCI, including a section on ‘tips and tricks’ for the most challenging cases. Finally, there is a discussion on the future of CTO-PCI including promising ongoing clinical trials and novel equipment that may improve outcomes and help to establish a more widespread adoption of CTO-PCI.