Reversal of ischemia of donor artery myocardium after recanalization of a chronic total occlusion

Procedural Results and Long-term Outcome of Chronic Total Occlusion Percutaneous Coronary Intervention in a UK Non-surgical Centre

Background

Chronic total occlusion (CTO) percutaneous coronary intervention (PCI) has evolved a great deal over recent years, with increased procedural success and lower complication rates being reported. This study aims to evaluate the feasibility, safety and success of a dedicated CTO programme in a large UK PCI centre without on-site cardiothoracic surgery facilities.

Methods

Clinical and procedural data were retrospectively collected for consecutive unselected patients undergoing CTO PCI between 2015 and 2019 from the local database and regional electronic patient records. In-hospital outcomes and long-term major adverse cardiovascular events (all-cause mortality, MI, stroke and target vessel revascularisation) were recorded.

Results

A total of 170 patients underwent 191 CTO procedures during the study period. The mean age was 63 ± 10 years and 80.6% of patients were male (n=137). The clinical indications were: stable chronic coronary syndromes in 88.5% (n=169) of patients; staged procedures in the context of acute coronary syndromes in 1.6% (n=3); and presentation with acute coronary syndrome in 9.9% (n=19). The procedural success rate was 50.0% (n=25) for general interventional cardiologists and 90.1% (n=127) for dedicated CTO operators. In-hospital major adverse cardiovascular events occurred once (0.5%) and interhospital transfer for emergency salvage cardiac surgery was not required. Long-term follow-up data at a median duration of 3.8 years revealed 4 (2.4%) cardiac deaths, 14 (8.3%) spontaneous MI events and 10 (5.9%) target vessel revascularisations.

Conclusion

These data suggest CTO PCI using contemporary techniques is both safe and effective when undertaken in a high-volume non-surgical centre by experienced operators.

The Role of Multimodality Imaging for Percutaneous Coronary Intervention in Patients With Chronic Total Occlusions

Background

Percutaneous coronary intervention (PCI) of Chronic total occlusions (CTOs) has been traditionally considered a challenging procedure, with a lower success rate and a higher incidence of complications compared to non-CTO-PCI. An accurate and comprehensive evaluation of potential candidates for CTO-PCI is of great importance. Indeed, assessment of myocardial viability, left ventricular function, individual risk profile and coronary lesion complexity as well as detection of inducible ischemia are key information that should be integrated for a shared treatment decision and interventional strategy planning. In this regard, multimodality imaging can provide combined data that can be very useful for the decision-making algorithm and for planning percutaneous CTO recanalization.

Aims

The purpose of this article is to appraise the value and limitations of several non-invasive imaging tools to provide relevant information about the anatomical characteristics and functional impact of CTOs that may be useful for the pre-procedural assessment and follow-up of candidates for CTO-PCI. They include echocardiography, coronary computed tomography angiography (CCTA), nuclear imaging, and cardiac magnetic resonance (CMR). As an example, CCTA can accurately delineate CTO location and length, distal coronary bed, vessel tortuosity and calcifications that can predict PCI success, whereas stress CMR, nuclear imaging and stress-CT can provide functional evaluation in terms of myocardial ischemia and viability and perfusion defect extension.

Prognostic Impact of Percutaneous Coronary Intervention of Chronic Total Occlusion in Acute and Periprocedural Myocardial Infarction

Coronary chronic total occlusion (CTO) has gained increasing clinical attention as the most advanced form of coronary artery disease. Prior studies already indicated a clear association of CTO with adverse clinical outcomes, especially in patients with acute myocardial infarction (AMI) and concomitant CTO of the non-infarct-related coronary artery (non-IRA). Nevertheless, the prognostic impact of percutaneous coronary intervention (PCI) of CTO in the acute setting during AMI is still controversial. Due to the complexity of the CTO lesion, CTO-PCI leads to an increased risk of complications compared to non-occlusive coronary lesions. Therefore, this review outlines the prognostic impact of CTO-PCI in patients with AMI. In addition, the prognostic impact of periprocedural myocardial infarction caused by CTO-PCI will be discussed.

Coronary physiology before and after chronic total occlusion treatment: what does it tell us?

Studies performed in the last two decades demonstrate that after successful percutaneous coronary intervention (PCI) of a chronically occluded coronary artery, the physiology of the chronic total occlusion (CTO) vessel and dependent microvasculature does not normalise immediately but improves significantly over time. Generally, there is an increase in fractional flow reserve (FFR) in the CTO artery, a decrease in collateral blood supply and an increase in FFR in the donor artery accompanied by an increase in blood flow and decrease in microvascular resistance in the myocardium supplied by the CTO vessel. Analogous to these physiological changes, positive remodelling of the distal CTO artery also occurs over time, and intravascular imaging can be helpful for analysing distal vessel parameters. Follow-up coronary angiography with physiological measurements after several weeks to months can be helpful and informative in a subset of patients in order to decide upon the necessity for treatment of residual coronary artery stenosis in the vessel distal to the CTO or in the contralateral donor artery, as well as in deciding whether stent optimisation is indicated. We suggest that such physiological guidance of CTO procedures avoids unnecessary overtreatment during the initial procedure, guides interventions at follow-up, and improves our understanding of what PCI in CTO means.

Debate of Percutaneous Coronary Intervention versus Coronary Artery Bypass Grafting in a Multimorbidity Patient with Complex Coronary Lesions

Background

While complete revascularization in coronary artery disease is of high priority, the method of implementation in patients with complex coronary lesions and multiple comorbidities is not directed by published guidelines. Case Presentation. A 53-year-old female with a chronic total occlusion of the right coronary artery and a bifurcation lesion of the left anterior descending artery and the first diagonal branch, presented with non-ST elevation myocardial infarction. Her past medical history concerned thymectomy and prior chest radiation for thymoma, myasthenia gravis, peripheral artery disease, and cervical cancer treated with surgery and radiation. Although SYNTAX score II favored surgical revascularization, the interventional pathway was finally successfully followed. However, it was complicated with vessel perforation and tamponade managed with pericardiocentesis.

Conclusion

Comorbidities are not all involved in common risk models and require individualization until more evidence comes to light.

Stress perfusion cardiovascular magnetic resonance and serial fractional flow reserve assessment of the left anterior descending artery in patients undergoing right coronary artery chronic total occlusion revascularization

Background

Fractional flow reserve (FFR) assessment of remote arteries, in the context of a bystander chronic total occlusion (CTO), can lead to false positive results. Adenosine stress cardiovascular magnetic resonance (CMR) evaluates perfusion defects across the entire myocardium and may therefore be a reliable tool in the work-up of remote lesions in CTO patients. The IMPACT-CTO study investigated donor artery invasive physiology before, immediately post, and at 4 months following right coronary artery (RCA) CTO percutaneous coronary intervention (PCI). The aim of this subanalysis was to assess the concordance between baseline perfusion CMR and serial FFR evaluation of left anterior descending artery (LAD) ischemia in patients from the IMPACT-CTO study.

Methods

Baseline adenosine stress CMR examinations from 26 patients were analyzed for qualitative evidence of LAD ischemia. The results were correlated with the serial LAD FFR measurements.

Results

The present findings demonstrated that before RCA CTO PCI, there was 62% agreement between perfusion CMR and FFR (ischemic threshold ≤ 0.8) in the assessment of LAD ischemia (k = 0.29; fair concordance). At 4 months after revascularization, there was 77% agreement (k = 0.52; moderate concordance) between the index CMR assessment of LAD ischemia and the follow-up LAD FFR. Concordance was improved at a LAD FFR ischemic threshold of ≤ 0.75.

Conclusions

In this hypothesis generating study, baseline CMR assessment of LAD ischemia correlated better with the 4 months LAD FFR data (threshold ≤ 0.8) as compared to the FFR measurements taken prior to RCA CTO revascularization.

Debates over NICE Guideline Update: What Are the Roles of Nuclear Cardiology in the Initial Evaluation of Stable Chest Pain?

Recent clinical trials have demonstrated the values of cardiac computed tomography (CT) in the initial evaluation of stable chest pain which led to drastic changes in the National Institute for Health and Care Excellence (NICE) guidelines in 2016. According to the updated NICE guidelines, cardiac CT should be performed as the initial cardiac testing in stable chest pain regardless of pre-test probability (PTP) of coronary artery disease (CAD). As a result, cardiac CT is now considered as a validated gatekeeper for assessing stable chest pain, which precedes all the functional studies including nuclear myocardial perfusion imaging (MPI). Nuclear MPI, in contrast, has been assigned as one of the second-line studies, which is inevitably dependent on the results of cardiac CT. However, nuclear MPI has genuine values in the diagnosis, treatment decision, and prognostic stratification of stable chest pain, which cannot be replaced by cardiac CT. In this review, the updated NICE guidelines and related cardiac CT trials will be critically reviewed from the view of nuclear physicians and the exceptional values of nuclear MPI will be described along with the future perspectives.

Utility of adjunctive modalities in Coronary chronic total occlusion intervention

Coronary chronic total occlusion (CTO) intervention remains one of the most challenging domains in interventional cardiology. Due to the technical challenges involved and potential procedural complications, CTO percutaneous coronary intervention (PCI) attempt and success rates remain less than standard PCI. However, the use of several adjunctive tools such as intravascular ultrasound, optical coherence tomography, rotational atherectomy, orbital atherectomy, excimer laser coronary atherectomy and percutaneous left ventricular assist device may contribute to improved CTO PCI success rates or provide better hemodynamic assessment of CTO lesion (i.e., using fractional flow reserve). In this review we present the current literature describing the utility and efficacy of these adjunctive modalities in CTO intervention.

Fractional Flow Reserve: Does a Cut-off Value add Value?

Fractional flow reserve (FFR) has been shown to improve outcomes when used to guide percutaneous coronary intervention (PCI). There have been two proposed cut-off points for FFR. The first was derived by comparing FFR against a series of non-invasive tests, with a value of ≤0.75 shown to predict a positive ischaemia test. It was then shown in the DEFER study that a vessel FFR value of ≥0.75 was associated with safe deferral of PCI. During the validation phase, a 'grey zone' for FFR values of between 0.76 and 0.80 was demonstrated, where a positive non-invasive test may still occur, but sensitivity and specificity were sub-optimal. Clinical judgement was therefore advised for values in this range. The FAME studies then moved the FFR cut-off point to ≤0.80, with a view to predicting outcomes. The ≤0.80 cut-off point has been adopted into clinical practice guidelines, whereas the lower value of ≤0.75 is no longer widely used. Here, the authors discuss the data underpinning these cut-off values and the practical implications for their use when using FFR guidance in PCI.

Correlation of Angina Pectoris and Perfusion Decrease by Collateral Circulation in Single-Vessel Coronary Chronic Total Occlusion Using Myocardial Perfusion Single-Photon Emission Computed Tomography

PURPOSE

To evaluate the perfusion decrease in donor myocardium by collateral circulation and its correlation with angina pectoris in patients with chronic total occlusion (CTO) using myocardial perfusion single-photon emission computed tomography (MPS).

MATERIALS AND METHODS

Thirty-six patients with single-vessel CTO without any other stenosis were included. All patients underwent MPS and coronary angiography (CAG) within 2 months. Total 72 donor arteries were evaluated for the grades of collaterals to the CTO artery using the Rentrop grading system on CAG. Perfusion defects and perfusion scores in donor and CTO territories were analyzed on MPS. Myocardial perfusion of donor and CTO territories were evaluated according to the presence of angina pectoris and the grades of collateral circulation.

RESULTS

When the CTO territory was ischemic, symptomatic patients showed higher summed difference scores in the CTO territory compared to asymptomatic patients (3.5 ± 2.4 vs. 1.5 ± 0.8 for symptomatic and asymptomatic groups respectively; p = 0.034). However, when the CTO territory was nonischemic, symptomatic patients showed higher summed stress scores (SSS, 4.3 ± 2.9 vs. 1.6 ± 1.2; p = 0.032) and summed rest scores (SRS, 4.2 ± 2.5 vs. 1.5 ± 1.1; p = 0.003) in the donor territories. On the per-vessel analysis, perfusion defects in donor territories were more frequent (0 % vs. 53 % vs. 86 % for Rentrop 0, Rentrop 1-2 and Rentrop 3, respectively; p < 0.001) and showed higher SSS (0.0 ± 0.0, 1.3 ± 1.6 and 2.1 ± 1.1 for Rentrop 0, Rentrop 1-2 and Rentrop 3, respectively; p = 0.001) and SRS (0.0 ± 0.0, 1.0 ± 1.4 and 1.7 ± 1.2; p = 0.003) at higher Rentrop grades, but their patterns were variable.

CONCLUSION

Angina pectoris was related to either ischemia of the myocardium beyond CTO or a perfusion decrease in the donor myocardium. The perfusion decrease in donor myocardium positively correlated with the collateral grades.

Physiologic significance of coronary collaterals in chronic total occlusions

Chronic total occlusions (CTOs) are commonly found in patients with coronary artery disease, and a system of collateral connections are found in almost all of these patients. These collateral vessels serve to prevent myocardial necrosis but are not sufficient to prevent myocardial ischemia during exercise. Unfortunately, the presence of well-developed collaterals has been used as argument against CTO revascularization. Many continue to falsely believe that these patients are "protected" by collaterals and, therefore, CTO recanalization is not indicated. Our knowledge of the physiologic significance of coronary collaterals has increased significantly over the past several years. Studies utilizing coronary pressure and flow velocity have answered a number of basic physiologic questions. We therefore sought to review the evidence for coronary collateral flow and their clinical significance in patients with CTOs.

Ventricular tachycardic storm with a chronic total coronary artery occlusion treated with percutaneous coronary intervention

A 66-year-old man with a history of coronary artery disease was evaluated due to ventricular tachycardic (VT) storm. The patient continued to have frequent recurrences of VT despite treatment with amiodarone and lidocaine. Since the ventricular arrhythmia could be related to myocardial ischemia related to a chronic total occlusion (CTO) of the right coronary artery, the patient underwent successful percutaneous coronary intervention of the CTO, followed by implantable cardioverter defibrillator implantation. He had no further episodes of VT during his hospital stay. After 9 months of follow-up, he had no further chest pain or clinically apparent recurrent ischemia. Interrogation of his defibrillator has shown brief nonsustained episodes of ventricular tachycardia, but the patient has not required delivery of a shock. The temporal association between treatment of the CTO and resolution of the VT, as well as the lack of recurrence of sustained VT, suggest a causative link between underlying ischemia produced by a chronically occluded coronary artery and provocation of VT and lend supportive evidence to this treatment approach.

Predictors and prevention of flow insufficiency due to limited flow demand

Background

We investigated the impacts of flow demand and native coronary stenosis on graft flow and patency.

Methods

We reviewed the angiograms of 549 bypass grafts in 301 patients who underwent off-pump coronary artery bypass grafting since 2007. Grafts consisted of 237 internal thoracic artery to left anterior descending artery; 97 internal thoracic artery and 52 saphenous vein grafts to left circumflex artery; and 109 gastroepiploic artery and 54 saphenous vein grafts to right coronary artery. We selected only individual bypass grafts created as the sole bypass graft to the coronary vascular region. Flow insufficiency was defined as ≤ 20 ml/min measured intraoperatively. When a significant difference in the incidence of flow insufficiency or “not functional” occurred between higher and lower values rather than the particular minimal luminal diameter value, the highest value was defined as the cut-off minimal luminal diameter. Distal lesions were defined as stenosis at segment #4, 7, 8, 12, 13, 14, or 15.

Results

Flow insufficiency was found in 112/549 (20.4%) bypass grafts. For internal thoracic artery to left circumflex artery grafts, the cut-off minimal luminal diameter for proximal and distal lesions was 1.25 mm and 0.75 mm, respectively. For gastroepiploic artery to right coronary artery grafts, the cut-off minimal luminal diameter was 0.82 mm for proximal lesions (p = 0.005), while 10 (71%) of 14 gastroepiploic artery grafts for distal lesions presented with flow insufficiency. Univariate and multivariate analysis identified a distal lesion (odds ratio (OR): 3.12, p < 0.0001); minimal luminal diameter greater than the cut-off value (OR: 3.64, p < 0.0001); right coronary artery (OR: 18.2, p = 0.0002) and left circumflex artery (OR; 2.29, p = 0.009) grafting; and a history of myocardial infarction in the grafted region (OR: 2.21, p = 0.02) as significant predictors of flow insufficiency.

Conclusions

Both competitive flow and insufficient flow demand cause graft failure. For distal lesions, more severe stenosis is necessary to avoid graft failure, compared with proximal lesions. A revascularization strategy for distal lesions should be discussed separately from that for proximal lesions.

Electronic supplementary material

The online version of this article (doi:10.1186/s13019-014-0188-3) contains supplementary material, which is available to authorized users.