Impact of collateralisation to a concomitant chronic total occlusion in patients with ST-elevation myocardial infarction: a subanalysis of the EXPLORE randomised controlled trial

Infarct-Related Artery as a Donor of Collaterals in ST-Segment-Elevation Myocardial Infarction With Concomitant Chronic Total Occlusion: Challenge of the Double-Jeopardy Thesis

BACKGROUND In ST-segment-elevation myocardial infarction (STEMI), a concomitant chronic total occlusion (CTO) in a non-infarct-related artery (NIRA) is associated with adverse outcome. In the case of the infarct-related artery (IRA) as a donor vessel for collaterals to the CTO, the IRA occlusion may lead to an acute threat to both the immediate IRA and the collaterally supplied CTO area, which has been described as a double-jeopardy effect. METHODS AND RESULTS We investigated the role of preformed intercoronary collaterals to the CTO originating from either the IRA or NIRA. Data were obtained from 2 hospitals participating in the prospective FITT-STEMI (Feedback Intervention and Treatment Times in ST-Segment Elevation Myocardial Infarction) study. From a total cohort of 2102 patients with acute STEMI, 93 patients had single-vessel CTO in an NIRA and well-developed intercoronary collaterals to the CTO. In-hospital mortality differed significantly with respect to the origin of the collaterals. Mortality was 15.2% with collaterals originating from the NIRA, 29.4% with a collateral origin from the IRA proximal to the acute STEMI occlusion, and 3.3% with a collateral origin from the IRA distal to the acute occlusion (P=0.044). A multivariate regression model confirmed that a proximal collateral origin had a significant higher mortality compared with a branching in the distal position from the acute STEMI occlusion (P=0.027; odds ratio = 20.8 [95% CI, 1.4-304.1]). CONCLUSIONS In STEMI with CTO in an NIRA, a CTO collateralization from the IRA distal to the acute occlusion is associated with a better prognosis. This finding challenges the double-jeopardy assumption as the main cause of adverse outcome in STEMI with CTO in an NIRA. REGISTRATION URL: https://www.clinicaltrials.gov; Unique identifier: NCT00794001.

The association of collaterals with myocardial ischemia and viability in chronic total occlusions

Collateral development in chronic total occlusions (CTO) is crucial to perfuse the distal myocardium and its angiographic evaluation is frequently used to assess the need for revascularization. We aimed to analyse the association between the presence of ischemia and hibernating myocardium, evaluated by cardiac [¹³ N]NH3/2-[¹⁸ F]FDG PET-CT, and the angiographic characterization of the collateral circulation. Prospective study including patients with a CTO who underwent a [¹³ N]NH3 and, when deemed necessary, 2-[¹⁸ F]FDG PET-CT. Well developed (WD) collaterals were defined as a concomitant angiographic Rentrop grade 3 and Werner collateral connection score 2 or 3, whereas the remaining as poorly developed (PD). 2% thresholds used to identify prognostic benefit of revascularization were applied: ischemia > 10% and hibernating myocardium > 7%. Fifty-nine patients (age 62.9±9.1 years, 58 male) were recruited, WD collaterals were present in 28 (47.5%). No significant differences were found in ischemia (WD 6.4±4.3 vs. PD 7.0±4.1, p = 0.64) and hibernation (WD 1.8±1.9 vs. PD 3.1±3.3, p = 0.18) scores. Most CTO territories demonstrated ischemia, but only 19 (46.3%) were associated with an area > 10% (WD 47.6% vs. PD 45.0%, p = 0.58). Scared non-viable myocardium was limited to 9 (15.3%) patients and was not associated with PD collaterals. Hibernating myocardium was frequent (54.2%), but just 6 (10.2%) CTO patients had an area of > 7% (WD 3.6% vs. PD 16.1%, p = 0.20). Collateral assessment by angiography has a poor association with the ischemic burden and hibernation state of CTO territories. Myocardial viability was present even in most CTO with angiographic PD collaterals.

Why and How Should We Treat Chronic Total Occlusion? Evolution of State-of-the-Art Methods and Future Directions

Chronic total occlusions are considered the most complex coronary lesion in interventional cardiology. The absence of visible lumen on angiography obscures the vessel course and makes vessel wiring unlikely with conventional techniques. Often a source of severe ischemia, chronic occlusions are also markers of advanced atherosclerosis that brings other complex features including lesion length, bifurcations, calcification, adverse vessel remodelling, distal disease, and anatomic distortion from previous bypass grafting. Often advanced atherosclerosis is associated with patient characteristics like left ventricular dysfunction, previous coronary bypass surgery, or multivessel disease that increase procedural demands and hazards. To accommodate these challenges new techniques and dedicated technologies have been developed. When applied to appropriate patients, these advances have improved procedural success, safety, and outcomes. Our aim is to provide the general cardiologist with an overview of these advances that can serve as a basis for counselling patients considered for revascularization.

Myocardial Viability, Functional Status, and Collaterals of Patients With Chronically Occluded Coronary Arteries

Objective: Viability and functional assessments are recommended for indication and intervention for chronic coronary total occlusion (CTO). We aimed to evaluate myocardial viability and left ventricular (LV) functional status by using cardiovascular magnetic resonance (CMR) and to investigate the relationship between them and collaterals in patients with CTO.

Materials and Methods: We enrolled 194 patients with one CTO artery as detected by coronary angiography. Patients were scheduled for CMR within 1 week after coronary angiography.

Results: A total of 128 CTO territories (66%) showed scar based on late gadolinium enhancement (LGE) imaging. There were 1,112 segments in CTO territory, while only 198 segments (18%) subtended by the CTO artery showed transmural scar (i.e., >50% extent on LGE). Patients with viable myocardium had higher LV ejection fraction (LVEF) (56.7 ± 13.5% vs. 48.3 ± 15.4%, p < 0.001) than those with transmural scar. Angiographically, well-developed collaterals were found in 164 patients (85%). There was no significant correlation between collaterals and the presence of myocardial scar (p = 0.680) or between collaterals and LVEF (p = 0.191). Nevertheless, more segments with transmural scar were observed in patients with poorly-developed collaterals than in those with well-developed collaterals (25 vs. 17%, p = 0.010).

Conclusion: Myocardial infarction detected by CMR is widespread among patients with CTO, yet only a bit of transmural myocardial scar was observed within CTO territory. Limited number of segments with transmural scar is associated with preserved LV function. Well-developed collaterals are not related to the prevalence of myocardial scar or systolic functioning, but could be related to reduce number of non-viable segments subtended by the CTO artery.

Do collaterals visualized on coronary angiography impact left ventricle ejection fraction among Asian Indians presenting with acute coronary syndrome?-The Deucalion Study

BACKGROUND

The coronary collaterals have been ascribed as a potential alternative source of myocardial perfusion to the extent that some suggest it as a "natural bypass"! We proposed to evaluate the impact of the extent of collaterals on left ventricle ejection fraction among Asian Indians presenting with acute coronary syndrome.

METHODS

This was a retrospective, all-comers study performed on consecutive 3614 patients presenting with the acute coronary syndrome. Angiograms were evaluated for collaterals graded according to Rentrop's classification among group A (grades 0 and 1) and group B (grades 2 and 3) collaterals.

RESULTS

Patients were matched for traditional cardiovascular risk factors in groups A and B as well as for ST elevation myocardial infarction and non-ST elevation myocardial infarction subgroups in both the groups. Grades 2 and 3 collaterals were significantly (P = 0.04) higher in patients with non-ST elevation myocardial infarction-266/1319 (20.17%), as compared to ST elevation myocardial infarction-group 400/2295 (17.43%). Left ventricle ejection fraction on presentation was better preserved in group A as compared to group B in those with double-vessel disease and triple-vessel disease patients with non-ST elevation myocardial infarction, whereas it was better in single-vessel disease and triple-vessel disease patients with ST elevation myocardial infarction. The inverse correlation (r = -0.111, P = 0.000) existed between left ventricle ejection fraction and grades of collaterals.

CONCLUSION

Patients with the single-vessel disease were more likely to have poor coronary collateral as compared to double-vessel disease/triple-vessel disease. Despite higher grade coronary collateral among Asian Indians presenting with acute coronary syndrome, both non-ST elevation myocardial infarction and ST elevation myocardial infarction patients with triple-vessel disease had significantly lower left ventricle ejection fraction. This paradoxically brings out worse left ventricle ejection fraction on presentation in those with double-vessel disease and triple-vessel disease with ST elevation myocardial infarction and single-vessel disease and triple-vessel disease with ST elevation myocardial infarction despite higher grade of coronary collateral representing as "Asian Indian Paradox" in our cohort.

Recovery of right ventricular function and strain in patients with ST-segment elevation myocardial infarction and concurrent chronic total occlusion

The right ventricle (RV) is frequently involved in ST-segment elevation myocardial infarction (STEMI) when the culprit or concurrent chronic total occlusion (CTO) is located in the right coronary artery (RCA). We investigated RV function recovery in STEMI-patients with concurrent CTO. In EXPLORE, STEMI-patients with concurrent CTO were randomized to CTO percutaneous coronary intervention (PCI) or no CTO-PCI. We analyzed 174 EXPLORE patients with serial cardiovascular magnetic resonance imaging RV data (baseline and 4-month follow-up), divided into three groups: CTO-RCA (CTO in RCA, culprit in non-RCA; n = 89), IRA-RCA (infarct related artery [IRA] in RCA, CTO in non-RCA; n = 56), and no-RCA (culprit and CTO not in RCA; n = 29). Tricuspid annular plane systolic excursion (TAPSE), RV ejection fraction (RVEF), RV global longitudinal strain (GLS) and free wall longitudinal strain (FWLS) were measured. We found that RV strain and TAPSE improved in IRA-RCA and CTO-RCA (irrespective of CTO-PCI) at follow-up, but not in no-RCA. Only RV FWLS was different among groups at baseline, which was lower in IRA-RCA than no-RCA (− 26.0 ± 8.3% versus − 31.0 ± 6.4%, p = 0.006). Baseline RVEF, RV end-diastolic volume and TAPSE were associated with RVEF at 4 months. RV function parameters were not predictive of 4 year mortality, although RV GLS showed additional predictive value for New York Heart Association Classification > 1 at 4 months. In conclusion, RV parameters significantly improved in patients with acute or chronic RCA occlusion, but not in no-RCA patients. RV FWLS was the only RV parameter able to discriminate between acute ischemic and non-ischemic myocardium. Moreover, RV GLS was independently predictive for functional status.

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.