Current diagnosis and management of left main coronary disease

Extrinsic compression of coronary and pulmonary vasculature

Coronary artery disease from atherosclerosis induced stenosis remains the leading cause of acute coronary syndrome (ACS) and death worldwide, however extrinsic compression of coronary arteries from adjacent anatomical and pathological structures is an infrequent but important diagnosis to be aware of, especially given the nonspecific symptoms of chest pain that mimic angina in patients with pulmonary hypertension (PHT) and congenital heart disease. Non-invasive CT angiography is an invaluable diagnostic tool for detection of coronary artery compression, pulmonary artery dilatation and pulmonary vascular compression. Although established guidelines are not available for management of left main coronary artery (LMCA) compression syndrome, percutaneous coronary intervention and stent implantation remain a feasible option for the treatment, specifically for patients with a high surgical risk. Treatment of pulmonary vein or artery compression is more varied and determined by etiology. This review article is focused on detailed discussion of extrinsic compression of coronary arteries, mainly the LMCA and brief discussion on pulmonary vasculature compression by surrounding anatomical and pathological entities, with focus on pathophysiology, clinical features, complications and role of imaging in its diagnosis and management.

Native aorto-ostial coronary lesions on CT coronary angiogram

Aorto-ostial coronary lesions (AOLs) are important to detect due to the high risk of catastrophic consequences. Unfortunately, due to the complexities of these lesions, they may be missed on invasive coronary angiography. Computed tomography coronary angiogram (CTCA) is highly sensitive and specific in detecting AOLs, and has the additional advantage of demonstrating the surrounding anatomy. CTCA is particularly useful when assessing for AOL aetiologies in addition to atherosclerotic disease, e.g.Congenital anomalies, extrinsic Compression, Iatrogenic, Arteritis and Other, such as Thrombus, Embolism, Dissection and Spasm. This gives rise to “CIAO (TEDS)” as a proposed aide-mémoire and will form the structure of this pictorial review.

Computational fluid dynamic-derived wall shear stress of non-significant left main bifurcation disease may predict acute vessel thrombosis at 3-year follow-up

Wall shear stress (WSS) plays a pivotal role on plaque progression in coronary artery disease. We assess the prognostic role of baseline mean WSS in developing a bifurcation-located myocardial infarction (B-MI) over the following 3 years in angiographically non-significant LM bifurcation disease. For this purpose, we retrospectively reviewed the procedural and medical records of consecutive patients evaluated in our center from 1st January 2014 to 1st January 2019 who had a non-significant LM bifurcation disease as evaluated at coronary computed tomography angiography (CCTA) and confirmed by coronary angiography. Each bifurcation model was reconstructed on the patient-specific geometries derived from the CCTA. The population was divided into two groups: patients with (n = 12) and without B-MI (n = 20) over the following 3 years. Both the mean WSSprox of each branch and the WSSentire_lesion of each vessel, adjusted for the respective mean lesions lengths and 3-dimensional percentage of stenosis (DS%), resulted in independent predictors of 3-year B-MI. Multivariate Cox-regression analysis confirmed that a baseline mean WSSentire_model ≥ 5.05 Pa (HR 1.98, 95% CI 1.83-2.10, p = 0.001) was a predictor of 3-year B-MI independently from the entire mean lesions lengths (HR 1.56. 95% CI 1.43.1.68, p = 0.002) and DS% (HR 1.26, 95% CI 1.18-1.37, p = 0.03). In conclusion, in patients with angiographically non-significant LM bifurcation disease, both the mean WSSprox of each branch and WSSentire_lesion of each stenotic vessel predicted the occurrence of B-MI over the following 3 years. Moreover, the WSSentire_bifurcation ≥ 5.05 Pa seems to be a predictor of 3-year B-MI independently from the DS% and lesions lengths.

Prognosis of Percutaneous Intervention of a Left Main Coronary Artery Stenosis Without the Use of Intravascular Imaging

Objectives

The aim of this study was to assess the prognosis in patients with left main coronary artery stenosis one year after percutaneous coronary intervention (PCI).

Methods

Our study included 40 patients who underwent PCI for left main coronary artery stenosis without the use of intravascular ultrasound (IVUS). Patients were followed for a year, and the prognostic effect of PCI on a composite end-point of revascularization, new myocardial infarction, cardiac death, and on all-cause mortality was assessed in multivariable Cox analysis.

Results

The multivariable analysis showed a good prognosis in patients receiving PCI with a total event rate of 7.5%. The independent predictors for major adverse cardiac events (MACE) were diabetes (p = 0.02). Other prognostic factors included in the model were gender, age, smoking, body mass index (BMI), hypertension, the complexity of the vessel, and ejection fraction.

Conclusion

PCI for left main coronary artery stenosis without the use of IVUS has a good prognosis after one year of clinical follow-up.

Incidence, predictors, clinical profile, management and outcome of patients with isolated left main coronary artery ostial disease

Objectives

Isolated left main coronary artery (LMCA) ostial disease is a rare variant of LMCA disease. Earlier studies on this disease are limited by small number of patients enrolled. The aim of the present study was to analyze the incidence, risk factors, clinical profile and long term outcome of patients with isolated LMCA ostial disease.

Methods

15,553 patients who underwent coronary angiogram in a single tertiary care cardiac hospital were analyzed for LMCA disease. 351(2.2%) patients were found to have significant LMCA disease out of which 28(0.18%) had isolated LMCA ostial disease. These 28 patients were compared with 323 non-ostial and non-isolated LMCA disease patients.

Results

The mean age of isolated LMCA ostial disease group was significantly less than the other group (p=0.009). Females were more affected than males (p=0.008). They also had low incidence of coronary risk factors (especially dyslipidemia, p=0.04). They tend to present more with stable angina and less with myocardial infarction. They had higher ejection fraction and normal regional wall motion (p=0.04). There was no mortality difference between two groups at the end of 1 year (p=0.234).

Conclusion

In one of the largest studies done in these patients, we found that isolated LMCA ostial disease is more common in middle aged females with few coronary risk factors. These patients also had a better ejection fraction and normal regional wall motion compared to patients with non-ostial and non-isolated LMCA disease. The clinical and angiographic profile of these patients suggests that they may represent a distinct clinical entity.

Intravascular ultrasound comparison of left main coronary artery disease between white and Asian patients

We assessed the ethnic differences in coronary atherosclerosis lesion morphology between white and Asian patients. Our hypothesis was that left main coronary artery (LMCA) disease was more focal and less complex in Asian than in Western white patients. We studied 99 Asian patients (Japan and South Korea) and 99 matched control United States white patients with a stable clinical presentation and >30% LMCA angiographic diameter stenosis by visual estimation. The matching parameters included age, gender, and diabetes mellitus. The vessel and lumen areas and calcium arc were analyzed every 0.5 mm and normalized for analysis length. Overall, 75.1% of the patients were men and 34.1% had diabetes. The patient age was 68.0 ± 10 years, with no differences between the Asian and white patients. The Asian patients had a lower prevalence of hyperlipidemia than the white patients (41.4% vs 81.8%; p <0.0001) and were smaller in size, and the white patients were more obese (body mass index 23.7 ± 2.6 vs 27.6 ± 4.1 kg/m(2), p <0.0001). The Asian patients had a smaller lumen area (5.2 ± 1.8 vs 6.2 ± 14 mm(2); p <0.0001), larger vessel area (20.0 ± 4.9 vs 18.4 ± 4.4 mm(2); p <0.0001), and larger plaque burden (72 ± 10 vs 64 ± 12%: p <0.0001) at the minimum lumen site and over the entire LMCA length. The white patients had more calcification, whether assessed by the maximum arc (82° ± 74° vs 49° ± 45°; p <0.0001) or total length (3.6 ± 3.2 vs 2.1 ± 2.1 mm; p <0.0001). In conclusion, after matching well-known risk factors, there appeared to be ethnic differences in coronary atherosclerosis morphology between Asian and white patients, at least as it affected LMCA morphology.

Computed tomography-based diagnosis of diffuse compensatory enlargement of coronary arteries using scaling power laws

Glagov's positive remodelling in the early stages of coronary atherosclerosis often results in plaque rupture and acute events. Because positive remodelling is generally diffused along the epicardial coronary arterial tree, it is difficult to diagnose non-invasively. Hence, the objective of the study is to assess the use of scaling power law for the diagnosis of positive remodelling of coronary arteries based on computed tomography (CT) images. Epicardial coronary arterial trees were reconstructed from CT scans of six Ossabaw pigs fed on a high-fat, high-cholesterol, atherogenic diet for eight months as well as the same number of body-weight-matched farm pigs fed on a lean chow (101.9±16.1 versus 91.5±13.1 kg). The high-fat diet Ossabaw pig model showed diffuse positive remodelling of epicardial coronary arteries. Good fit of measured coronary data to the length-volume scaling power law ( where L(c) and V(c) are crown length and volume) were found for both the high-fat and control groups (R(2) = 0.95±0.04 and 0.99±0.01, respectively). The coefficient, K(LV), decreased significantly in the high-fat diet group when compared with the control (14.6±2.6 versus 40.9±5.6). The flow-length scaling power law, however, was nearly unaffected by the positive remodelling. The length-volume and flow-length scaling power laws were preserved in epicardial coronary arterial trees after positive remodelling. K(LV) < 18 in the length-volume scaling relation is a good index of positive remodelling of coronary arteries. These findings provide a clinical rationale for simple, accurate and non-invasive diagnosis of positive remodelling of coronary arteries, using conventional CT scans.

10 plus-years follow-up after patch angioplasty of the left main coronary artery

In ostial or proximal left main coronary artery (LMCA) obstruction, re-establishment of normal antegrade flow via the main trunk may be preferable to distal bypass grafting. The objective of this study was to assess the effectiveness of patch plasty of the left main (LM) trunk of the coronary artery for more than 10 years. Direct widening of the LMCA was recommended to patients with ostial, proximal, or midpoint stenosis of the main trunk. Group I of 16 patients had isolated LM obstruction with no distal disease, and Group II of 15 patients had, in addition, right coronary obstruction. The mean age was 60.9 years (age group, 47 to 83 years). Nineteen patients underwent this operation through an anterior transverse aortotomy. No endarterectomies were performed. In Group II, in addition, a single saphenous vein bypass graft was placed in the right coronary artery. There were no operative deaths. Follow-up period extends from 10 to 18 years (mean 11.2). Eight patients had angiography from 3 to 9 years after surgery and all show adequate LM trunk caliber. Noncardiac deaths occured in five patients (26.3%) at 2 months, and 1, 4, 6, and 7 years after surgery. Two women with isolated ostial stenosis diagnosed as a spasm have not shown progression of coronary disease 7 to 9 years after the operation. Widening of the LMCA should be considered in selective cases, only when ostial, proximal, or midportion stenosis of the main vessel exist, even if a right coronary bypass graft is required.

New era of left main coronary artery treatment strategy

For several decades of medical history, coronary-artery bypass grafting (CABG) has been regarded as the best treatment option for patients with unprotected left main coronary artery (LMCA) disease, considering lesion priority and its clinical consequences. Over the time, with remarkable advancements in techniques of percutaneous coronary intervention (PCI), supporting devices, and adjunctive pharmacologic therapy, PCI with DES implantation has appeared to be new and alternative option for optimal revascularization therapy for these patients. The available cumulative evidence suggests that the safety outcomes such as mortality or composite of death, myocardial infarction and stroke are similar among PCI and CABG for patients with LMCA disease, the only difference was the rate of repeat revascularization. Current evidence and ongoing large clinical trials may encourage interventional cardiologists to choose PCI with stenting as an alternative revascularization strategy for unprotected LMCA disease in future. Finally, this evidence will change the current clinical practice and the guideline of optimal revascularization strategy for unprotected LMCA disease.

Treatment of patients with left main coronary artery disease

OPINION STATEMENT

Considering lesion priority and its clinical consequences, coronary artery bypass grafting (CABG) has been a treatment of choice for revascularization in patients with significant left main coronary artery (LMCA) disease, However, with remarkable advancements in techniques of percutaneous coronary intervention (PCI), supporting devices, and adjunctive pharmacologic therapy, PCI with stenting has emerged to be a less invasive and feasible revascularization treatment for these patients. The cumulative evidence suggests that the safety outcomes such as mortality or composite of death, myocardial infarction, and stroke are similar among PCI and CABG, with the only difference being the rate of repeat revascularization. Based on these data, the current guideline of revascularization of LMCA disease has adopted an increasing off-label experience with stenting and clinical studies and been updated to partly approve PCI as a viable alternative (in level of class IIb) in selected patients. The choice of PCI or CABG for unprotected LMCA disease depends on several clinical and anatomic features, ensuring crucial patient selection to be a cornerstone for achieving favorable long-term outcomes. In patients with very complex anatomic features and concomitant diffuse multivessel disease, CABG is preferred so as to avoid procedural and future thrombotic risks and to provide more complete revascularization. By contrast, in patients with relatively simple LMCA disease, such as ostial/shaft LMCA disease, isolated LMCA disease (with or without one or two-vessel involvement), and LMCA disease with low SYNTAX score, PCI is an alternative, and in some cases a preferred, strategy to reduce surgical risks (eg, stroke and in-hospital events following major surgery). For the future, ongoing large clinical trials might also boost interventional cardiologists to select PCI with stenting as an alternative revascularization strategy for unprotected LMCA disease. This evidence will most likely change the current clinical practice and guidelines of optimal revascularization strategy for unprotected LMCA disease.

The role of common variants of the cholesteryl ester transfer protein gene in left main coronary artery disease

BACKGROUND

The cholesteryl ester transfer protein (CETP) has a central role in the lipid metabolism and therefore may alter the susceptibility to atherosclerosis.

METHODS

The DNA of 471 subjects [133 subjects with angiographically documented left main coronary artery disease (LMCAD), 241 subjects with more peripheral coronary artery disease (MPCAD) and 97 subjects self reported healthy (Controls)] was analyzed for the frequency of TaqIB and I405V polymorphisms in the gene coding CETP.

RESULTS

There is no significant difference in CETP allele frequency or genotype distribution among LMCAD and MPCAD patients although there is statistical difference between LMCAD and Controls (p = 0.001). Specifically, patients with LMCAD and B1B1 genotype of TaqIB polymorphism were more frequent present compared to Controls (33.8% vs 22.9%, respectively). The frequency of B2B2 genotype was 3 times lower in the LMCAD group compared to Controls (10.5% vs 30.2%, respectively). In the LMCAD group the frequency of B1 allele compared to Controls was higher (62% vs 46%, respectively, p = 0.001). The relationship between TaqIB gene polymorphism and the LMCAD was independent of lipid profile, with the exception of apolipoprotein A.

CONCLUSIONS

These findings indicate that the TaqIB polymorphism may have potential importance in screening individuals at high risk for developing CAD. However, this polymorphism cannot distinguish between LMCAD and MPCAD. Further prospective investigations in larger populations are required to confirm these findings.