Left main coronary artery disease: assessment, diagnosis, and therapy

Fracture and plastering of distal left main stent during double-kissing Culotte technique: a case report

Background

Acute fracture of a left main (LM) stent during angioplasty is a rare complication. Cardiologists should be aware of the risk of stent fracture (SF) following kissing balloon inflation (KBI) even if the effective diameter of the balloons does not exceed the recommended expansion limits of stents.

Case summary

A 64-year-old female with hypertension and dyslipidaemia presented with crescendo angina since three months in spite of optimal medical therapy. Coronary angiogram showed a distal LM bifurcation lesion. The patient was admitted for LM bifurcation stenting by upfront two-stent technique (inverted double-kissing Culotte technique). Following first KBI of the stent placed from left circumflex artery (LCX) to LM, there was stent deformation in the LM shaft. As we had planned the Culotte technique, we decided to exclude the fractured segment by stenting from left anterior descending artery (LAD) to LM. The stent from LAD-LM successfully excluded the fractured part of the first stent from the lumen of LM. Optical coherence tomography done after final KBI from LCX-LM revealed successful exclusion of the deformed segment of the LCX stent with mild malapposition at the site of the deformed stent. A follow-up angiogram after six months showed normal in-stent flow with no evidence of restenosis or pseudoaneurysm.

Discussion

Acute LM SF during coronary intervention can occur even if the effective cumulative diameter of the inflated balloons does not exceed the mentioned expansion limit of stents. Intravascular imaging is a helpful modality to define type of SF and its management.

Bilateral isolated coronary ostial stenosis in a middle-aged premenopausal woman with vasospastic angina: a case report

Background

Vasospastic angina (VSA) is uncommon in premenopausal women who have less chronic endothelial injury causing vascular remodelling, considered to play a primary role in the pathogenesis for coronary vasospasms. Furthermore, vasospasms rarely occur in the bilateral coronary ostia. Isolated coronary ostial stenosis (ICOS), which often causes severe effort angina and requires surgical intervention, is more commonly reported in middle-aged women, with causes including fibromuscular dysplasia (FMD) and large-vessel vasculitis. However, ICOS associated with VSA is extremely rare.

Case summary

A 50-year-old premenopausal Japanese woman presented with a complaint of typical chest pain due to angina during light exertion daily in the early morning hours since 3 years. Coronary angiography (CAG) revealed bilateral mild-to-moderate ICOS in addition to multi-vessel spasms involving the bilateral coronary ostia confirmed by the vasospasm provocation test using intracoronary acetylcholine injection. Tests to determine the cause of ICOS did not identify FMD or any other disease. The angina attacks alleviated after calcium channel blocker (CCB) administration without intervention for bilateral ICOS for 24 years since the first presentation. Moreover, coronary computed tomography angiography (CTA) performed 24 years after the first presentation showed no ICOS.

Discussion

In our patient with typical and frequent VSA symptoms, CAG revealed both mild-to-moderate ICOS and the vasospasms in the bilateral coronary ostia. Fibromuscular dysplasia or large-vessel vasculitis was ruled out as the causes of ICOS. Vasospastic angina rarely occurred after the prescription of CCB, and coronary CTA 24 years after the first presentation showed no ICOS. Bilateral ICOS in our patient might be VSA related.

Assessment of left main coronary artery disease: a comparison between invasive and noninvasive

Left main coronary artery disease has significant therapeutic as well as prognostic implications. The presence of left main coronary artery stenosis is strongly associated with poor short- and long-term prognoses. Accurate identification of left main stenosis is extremely important since it would be the main factor to guide management. There are several modalities used to determine the presence of atherosclerosis and the degree of stenosis in a left main coronary artery. Newer modalities allow for an accurate evaluation of left main stenosis and atherosclerosis. In this review, we go through different invasive and noninvasive modalities to diagnose left main stenosis, shedding more light into coronary computed tomography angiography, and its accuracy in this specific diagnosis.

PCI or CABG for Left Main Disease: Does Disease Location Matter?

PURPOSE OF REVIEW

This review attempts to specifically assess impact of disease location in left main artery on mortality and cardiovascular outcomes in patients treated with percutaneous coronary intervention versus coronary artery bypass surgery.

RECENT FINDINGS

The management of left main disease, once thought to be the sole province of cardiothoracic surgeon, has recently undergone a reappraisal by the cardiovascular medicine community. For many years, societal guideline recommendations advised bypass surgery as the "de rigeur" method of revascularization for unprotected left main disease. However, recent studies suggest that coronary intervention, especially with advances in drug-eluting stent technology, has mounted a serious challenge to surgical bypass in treatment of this disease. Although overall mortality rates are comparable for percutaneous coronary intervention and bypass surgery, left main disease location does influence long-term outcomes for percutaneous coronary intervention more than bypass surgery. A patient- and lesion-centered approach to treatment of this disease may provide optimal outcomes.

Forward-viewing estimation of 3D blood flow velocity fields by intravascular ultrasound: Influence of the catheter on velocity estimation in stenoses

Coronary artery disease is the most common type of cardiovascular disease, affecting > 18 million adults, and is responsible for > 365 k deaths per year in the U.S. alone. Wall shear stress (WSS) is an emerging indicator of likelihood of plaque rupture in coronary artery disease, however, non-invasive estimation of 3-D blood flow velocity and WSS is challenging due to the requirement for high spatial resolution at deep penetration depths in the presence of significant cardiac motion. Thus we propose minimally-invasive imaging with a catheter-based, 3-D intravascular forward-viewing ultrasound (FV US) transducer and present experiments to quantify the effect of the catheter on flow disturbance in stenotic vessel phantoms with realistic velocities and luminal diameters for both peripheral (6.33 mm) and coronary (4.74 mm) arteries. An external linear array ultrasound transducer was used to quantify 2-D velocity fields in vessel phantoms under various conditions of catheter geometry, luminal diameter, and position of the catheter relative to the stenosis at a frame rate of 5000 frames per second via a particle imaging velocimetry (PIV) approach. While a solid catheter introduced an underestimation of velocity measurement by > 20% relative to the case without a catheter, the hollow catheter introduced < 10% velocity overestimation, indicating that a hollow catheter design allowing internal blood flow reduces hemodynamic disturbance. In addition, for both peripheral and coronary arteries, the hollow catheter introduced < 3% deviation in flow velocity at the minimum luminal area compared to the control case. Finally, an initial comparison was made between velocity measurements acquired using a low frequency, catheter-based, 3-D intravascular FV US transducer and external linear array measurements, with relative error < 12% throughout the region of interest for a flow rate of 150 mL/min. While further system development is required, results suggest intravascular ultrasound characterization of blood flow velocity fields in stenotic vessels could be feasible with appropriate catheter design.

Left main coronary artery disease: pathophysiology, diagnosis, and treatment

The advent of coronary angiography in the 1960s allowed for the risk stratification of patients with stable angina. Patients with unprotected left main coronary artery disease have an increased risk of death related to the large amount of myocardium supplied by this vessel. Although coronary angiography remains the preferred imaging modality for the evaluation of left main coronary artery stenosis, this technique has important limitations. Angiograms of the left main coronary artery segment can be difficult to interpret, and almost one-third of patients can be misclassified when fractional flow reserve is used as the reference. In patients with clinically significant unprotected left main coronary artery disease, surgical revascularization was shown to improve survival compared with medical therapy and has been regarded as the treatment of choice for unprotected left main coronary artery disease. Two large-scale clinical trials published in 2016 support the usefulness of catheter-based revascularization in selected patients with unprotected left main coronary artery disease. In this Review, we describe the pathophysiology of unprotected left main coronary artery disease, discuss diagnostic approaches in light of new noninvasive and invasive imaging techniques, and detail risk stratification models to aid the Heart Team in the decision-making process for determining the best revascularization strategy for these patients.

Impact of annular and supra-annular CoreValve deployment locations on aortic and coronary artery hemodynamics

CoreValve is widely used in transcatheter aortic valve replacement, but the impact of its deployment location on hemodynamics is unexplored despite a potential role in subsequent aortic and coronary artery pathologies. The objectives of this investigation were to perform fluid-structure interaction (FSI) simulations for a 29 mm CoreValve deployed in annular vs supra-annular locations, and characterize resulting hemodynamics including velocity and wall shear stress (WSS). Patient-specific geometry was reconstructed from computed tomography scans and CoreValve was deployed using a finite element approach. FSI simulations were then performed using a boundary conforming method and realistic boundary conditions. Results showed that CoreValve deployment location impacts hemodynamics in the ascending aorta and flow patterns in the coronary arteries. During peak-systole, annularly deployed CoreValve produced a jet-like flow structure impinging on the outer-curvature of the ascending aorta. Supra-annularly deployed CoreValve having a lateral tilt of 10° led to a more centered jet impinging further downstream. At mid-systole, valve leaflets of the annularly deployed CoreValve closed asymmetrically leading to disorganized flow patterns in the ascending aorta vs those from the supra-annular position. Supra-annularly deployed CoreValve also led to high-velocity para-valvular flow supplying the coronary arteries. CoreValve in the supra-annular position significantly (P < 0.05) elevated WSS within the first few diameters of both coronary arteries as compared to the annular position for many time points quantified. These results afforded by the advanced simulation methods may have important clinical implications given the role of aortic hemodynamics in dilation and the pro-atherogenic nature of WSS alterations in the coronary arteries.

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.

Isolated and Significant Left Main Coronary Artery Disease: Demographics, Hemodynamics and Angiographic Features

Left main coronary artery disease carries a poor prognosis. The etiology of isolated and significant left main coronary artery (ILMCA) disease is not well understood. Studies so far were limited by small numbers. The authors identified 46 patients with ILMCA disease from their database over 10 years (group I) and compared them with 83 consecutive patients undergoing catheterization (group II). They also compared patients with ostial vs distal ILMCA disease. Group I represented 0.1% of catheterization patients. The demographic profile and atherosclerotic risk factor profile of the 2 groups as well as ostial and distal ILMCA disease were compared. This is the largest study of ILMCA disease. Risk factors for atherosclerosis were commonly seen. Nonatherosclerotic causes of ILMCA disease were not seen. This study suggests coronary atherosclerosis as the predominant cause of ILMCA disease. ILMCA disease is more common in women. Diabetes is more commonly associated with distal ILMCA lesion. There is a trend suggesting that ostial ILMCA lesion is more common in smokers and women.

Left main coronary arterial endothelial function and heterogenous segmental epicardial vasomotor reactivity in vivo: novel insights with intravascular ultrasonography

AIMS

While the relationship between epicardial coronary vasomotor reactivity and cardiovascular events is well established, this observation has yet to be evaluated within the left main coronary artery (LMCA) in humans in vivo. Our aims were to test the endothelium-dependent vasomotor properties of the LMCA, and to compare these responses to downstream epicardial segments.

METHODS AND RESULTS

Thirty patients referred for coronary angiography underwent intracoronary (IC) salbutamol provocation during intravascular ultrasound imaging within a non-critically diseased, left-sided conduit vessel. Macrovascular vasomotor response [change in average lumen area (LA) at baseline and following 5 min of 0.30 µg/min IC salbutamol] and percent atheroma volume (PAV) were evaluated in 30 LMCA, 42 proximal, 109 mid, and 132 distal epicardial coronary segments. In comparison with all other segments, the LMCA had the greatest lumen and vessel areas (P < 0.001), yet the proximal epicardial segments contained the greatest PAV (P < 0.02). The mid and distal epicardial segments displayed significant endothelium-dependent vasodilatation from baseline (P = 0.017 and <0.001, respectively); however, the proximal epicardial and LMCA segments did not (P = 0.45 and 0.16, respectively). Significant segmental vasomotor heterogeneity was noted in all 30 patients, with opposing vasomotor responses between adjacent LMCA and epicardial segments. Across all segments, baseline LA inversely correlated with the % change in LA (r = -0.16, P = 0.0005).

CONCLUSION

Endothelium-dependent vasomotor reactivity is heterogenous within the conduit coronary system. Vascular dynamic responses were less prominent in the larger calibre LMCA and proximal epicardial segments. This may, in part, relate to higher shear stress in smaller, distal segments and yet also may explain the propensity for culprit plaques to cluster proximally.

Coexistence of left main and right coronary artery ostial stenosis: demographic and angiographic features

This study was designed to evaluate ostial left main coronary artery (LMCA) stenosis and investigate concomitant stenotic lesions of LMCA and right coronary arteries (RCA) and their demographic and angiographic features. We evaluated 11,283 patients who underwent coronary angiography. Patients were placed into four groups according to having ostial or nonostial LMCA or RCA stenosis. Significant LMCA stenosis was observed in 242 (8.3%) of the patients, and only 68 (28.1%) of them had significant ostial LMCA stenosis. There was a significant correlation between ostial stenosis of LMCA and RCA (p = 0.03). The frequency of female gender was greater in ostial LMCA and ostial RCA stenosis groups compared with the other groups (p = 0.01). Ostial LMCA and RCA stenosis were related significantly. Both female predominance and coexistence of ostial LMCA and RCA stenosis might have suggest a different pathological ground for this disease.

Impact of plaque burden in the left main coronary artery determined by intravascular ultrasound on cardiovascular events in a Japanese population undergoing percutaneous coronary intervention

The left main coronary artery (LMCA) is a particularly important target of atherosclerotic plaque accumulation. The aim of this study was to investigate the connection between subclinical plaque burden in the LMCA measured by intravascular ultrasound and future cardiovascular events. Two hundred eighteen consecutive patients underwent percutaneous coronary intervention for the left anterior descending coronary artery or the left circumflex coronary artery under intravascular ultrasound guidance. Plaque burden in the LMCA was analyzed for these patients, and major adverse cardiac events were also evaluated. Data were analyzed by grouping the patients into tertiles according to plaque burden values; tertile 1, <32% area stenosis; tertile 2, 32% to 45% area stenosis; and tertile 3, >45% area stenosis. During a 3-year follow-up period (average 16.1 months), 12% of tertile 1, 18% of tertile 2, and 40% of tertile 3 experienced major adverse cardiac events, mostly due to repeat revascularization (p <0.001). On Cox multivariate analysis, plaque burden in the LMCA (per percentage) detected by intravascular ultrasound remained an independent significant predictor of major adverse cardiac events (hazard ratio 1.04, 95% confidence interval 1.02 to 1.07) and future revascularization (hazard ratio 1.05, 95% confidence interval 1.02 to 1.07) (p <0.001). In conclusion, plaque burden in the LMCA is useful as an indicator of coronary atherosclerosis and may be a significant predictor of cardiovascular events, especially revascularization.

Stent fracture at the proximal shaft of the left main stem

Stent fracture is likely to be caused due to mechanical stress at the hinge point or kinking movement at the point of aneurysm formation with stent malapposition. To our knowledge, this is the first published report of stent fracture at the proximal shaft of the left main stem in a patient with acute myocardial infarction.

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.

Ostial left main coronary artery stenosis as an additional risk factor in off-pump coronary artery bypass grafting

BACKGROUND

Our aim was to determine whether general left main coronary artery stenosis (LMS) and ostial LMS pose additional risks after off-pump coronary artery bypass grafting (CABG) relative to non-left main coronary artery stenosis.

METHODS

From January 1, 2008, to December 31, 2009, 4366 patients underwent primary isolated off-pump CABG at Beijing Anzhen Hospital. Disease was retrospectively classified as non-left main disease (n = 3523), nonostial LMS (n = 765), and ostial LMS (n = 78). Groups were propensity score matched. Kaplan-Meier freedoms from major adverse cardiac and cerebrovascular events (MACCEs) were calculated.

RESULTS

During the first 30 postoperative days, mortality was significantly higher in the ostial LMS group (6.41%) than in non-left main disease (0.855%, χ(2) = 7.78, P = .005) and nonostial LMS (1.28%, χ(2) = 4.71, P = .03) groups. Incidence of MACCEs was significantly higher in the ostial LMS group (20.5%) than in non-left main disease (5.98%, P = .000) and nonostial LMS (9.62%, P = .002) groups. Odds ratio for early MACCEs of ostial LMS versus non-left main disease was 3.74 (95% confidence interval, 1.72-8.17). At mean follow-up 12.8 ± 7.5 months and cumulative follow-up 498.5 patient-years, difference among groups in freedom from MACCEs did not reach statistical significance (χ(2) = 2.39, P = .303).

CONCLUSIONS

Ostial LMS poses additional early risks of mortality and MACCEs in off-pump CABG. Off-pump CABG for ostial LMS should proceed with greater of intraoperative surveillance and lower threshold for converting to on-pump CABG.

Impact of the low- to high-density lipoprotein cholesterol ratio on composition of angiographically ambiguous left main coronary artery plaque

BACKGROUND

A high low-density lipoprotein cholesterol (LDL-C) to a high-density lipoprotein cholesterol (HDL-C) ratio is associated with cardiac events, while the left main coronary artery (LMCA) is considered to be an important target of atherosclerotic plaque accumulation. This aim of the present study was to investigate the relationship between a LDL-C/HDL-C ratio and the characteristics of tissue components of LMCA plaque.

METHODS AND RESULTS

One-hundred-twenty consecutive patients with stable angina pectoris who received chronic statin treatment underwent percutaneous coronary intervention for the left coronary artery. We prospectively performed integrated backscatter (IB) intravascular ultrasound (IVUS) to their LMCAs and evaluated the tissue characteristics. According to the median value of their LDL-C/HDL-C ratios (2.4), they were divided into 2 groups [high LDL-C/HDL-C ratio (>2.4) (n=60) or low LDL-C/HDL-C ratio (≤ 2.4) (n=60)]. There was no significant difference in the data analyzed using conventional IVUS between the 2 groups. In the IB-IVUS analysis, patients with a high LDL-C/HDL-C ratio had a larger lipid volume and a smaller fibrous volume compared to patients with a low LDL-C/HDL-C ratio (52 ± 10% vs. 48 ± 10%, P=0.014 and 45 ± 9% vs. 50 ± 10%, P=0.010).

CONCLUSIONS

A high LDL-C/HDL-C ratio was associated with a high percentage of lipid volume and a low percentage of fibrous volume in LMCA lesions. Our findings might well suggest the increased risk of cardiovascular events in patients with a high LDL-C/HDL-C ratio.

Tissue characterisation of atherosclerotic plaque in coronary artery bifurcations: an intravascular ultrasound radiofrequency data analysis in humans

AIMS

To investigate tissue characteristics of atherosclerotic plaques in coronary artery bifurcations.

METHODS AND RESULTS

Using a global virtual histology registry, geometric and compositional characteristics of plaque in three segments (proximal, distal, and at the bifurcation) of coronary bifurcation sites were analysed with intravascular ultrasound radiofrequency data (RFD) analysis. A total of 256 bifurcation sites were analysed: left main (LM)-left anterior descending artery (LAD), 41; LAD-diagonal artery, 128; left circumflex artery-obtuse marginal artery, 34; and right coronary artery-acute marginal artery, 53. The plaque+media (P+M) burden was larger in the distal segments of LM-LAD bifurcation sites than in the proximal and at the bifurcation segments (46.55±12.08% vs. 40.40±11.76%, 41.15±11.01%, p<0.001). The % necrotic core (NC) and % dense calcium (DC) at the bifurcation and distal segments of LM-LAD bifurcation sites was significantly greater than in the proximal segments (6.75±5.09%, 7.36±6.01% vs. 4.89±4.78%, p<0.05, and 3.31±2.87%, 3.73±3.28% vs. 1.89±2.10%, p<0.001). In contrast, P+M burden, % NC and % DC in the proximal segments of non-LM bifurcation sites was significantly greater than at the bifurcation and distal segments (49.41±12.12% vs. 45.34±11.21%, 46.80±10.68% / 8.08±6.21% vs. 6.47±5.11%, 6.28±5.05% / 4.57±4.67% vs. 3.38±3.44%, 3.55±3.74%, all p<0.001).

CONCLUSIONS

The results demonstrate that heterogeneous nature of coronary atherosclerosis at coronary bifurcations according to their segments and anatomical locations (LM-LAD vs. non-LM bifurcations). The further investigation for the clinical efficacy of the RFD analysis on bifurcation sites are warranted.

Remodeling is a more important determinant of lumen size than atheroma burden in left main coronary artery disease

BACKGROUND

Left main coronary artery (LMCA) disease influences survival; however, the predictors of LMCA changes over time are incompletely understood.

METHODS

Paired intravascular ultrasound (IVUS) and core laboratory analyses were performed in a standardized fashion in 207 subjects (mean +/- SD age 58 +/- 10 years, 80% men). The average follow-up duration was 18 months (range 12-24 months). The IVUS measurements were first obtained at the smallest lumen area and the largest plaque area at follow-up and the corresponding positions in the LMCA were then measured at baseline.

RESULTS

The LMCA percentage of atheroma area at baseline was 38.2% +/- 11.8%, and 133 patients (64%) experienced an increase in percentage of atheroma area. Change in lumen area correlated positively with change in total vessel area (R = 0.85, P < .0001) and negatively with change in percentage of atheroma area (R = -0.58, P < .0001). Change in plaque area correlated well with change in total vessel area (R = 0.64, P < .0001) but only weakly with change in lumen area (r = 0.14, P = .039). Although LMCA length correlated negatively with baseline lumen area and total vessel area, it did not correlate with their changes over time. On multivariable analyses, current smoking predicted an increase in percentage of atheroma area (P = .0013) and plaque area (P = .0041). Height negatively predicted change in percentage of atheroma area (P = .001).

CONCLUSIONS

The LMCA lumen dimensions are more tightly linked with remodeling than with atheroma progression/regression.

How good are experienced interventional cardiologists at predicting the functional significance of intermediate or equivocal left main coronary artery stenoses?

BACKGROUND

Decisions for coronary revascularisation are frequently based on visual assessment of the severity of a stenosis. In patients with intermediate left main stem lesions clinical decision making based on FFR is safe and feasible. This study was performed to assess the accuracy of visual angiographic assessment of intermediate or equivocal left main coronary artery (LMCA) stenoses by experienced interventional cardiologists when taking fractional flow reserve (FFR) measurements as the gold standard.

METHODS

Fifty-one patients with intermediate (40-80% diameter stenosis by angiography) or equivocal LMCA disease were evaluated by FFR. Angiograms were then reviewed by 4 experienced interventionalists from different university hospitals blinded to FFR results. Lesions were visually assessed and their significance classified as 'significant', 'not significant', or 'unsure' if the observer was unable to make a decision regarding lesion significance based on the angiogram.

RESULTS

Results were compared with two different FFR cutoff values (< 0.75 and < or = 0.80) for hemodynamic significance. The 4 reviewers achieved correct lesion classification in no more than approximately 50% of cases each, regardless of FFR threshold. The interobserver agreement between two reviewers in excess of the agreement expected due to chance was outperformed on average by only 16%. Furthermore, interobserver variability was large resulting in unanimously correct lesion classification in only 29% of all cases.

CONCLUSIONS

The functional significance of intermediate and equivocal LMCA stenoses should not be based solely on angiographic assessment even by experienced interventional cardiologists.

A Randomized Comparison of Paclitaxel-Eluting Stents Versus Bare-Metal Stents for Treatment of Unprotected Left Main Coronary Artery Stenosis

OBJECTIVES

To optimize percutaneous coronary intervention (PCI) strategy for unprotected left main (LM) disease, we performed a randomized study: intravascular ultrasound (IVUS)-guided bare-metal stent (BMS) or paclitaxel-eluting stent (PES) implantation after lesion pre-treatment with cutting balloon (CB) for unprotected LM lesions.

BACKGROUND

Recent studies have shown promising results in terms of safety and feasibility for patients with LM disease who underwent PCI with stent implantation. However, comparison of BMS and PES for LM lesions has not yet been evaluated.

METHODS

One hundred three patients were randomly assigned to receive BMS (n = 50) or PES (n = 53) implantation. All interventions were IVUS guided, and CB pre-treatment before stenting was performed in all patients. All patients were scheduled for 6-month follow-up.

RESULTS

Baseline clinical characteristics were comparable in both cohorts. Stent implantation was successful in all lesions. Follow-up analysis showed binary restenosis in 11 (22%) BMS and in 3 (6%) PES patients (p = 0.021). By IVUS, percentage of neointimal volume obstruction at 6 months was reduced from 25.20 +/- 22.02% with BMS to 16.60 +/- 17.25% with PES (p = 0.02). At 6 months, the major adverse cardiac event-free survival rate was 70% in BMS and 87% in PES patients (p = 0.036).

CONCLUSIONS

This study demonstrates that PCI of LM with IVUS guidance and CB pre-treatment is safe and effective. No serious procedure-related complications were observed, and clinical outcomes appeared to be good. Finally, the findings demonstrate that implantation of PES may be superior to BMS in the large-diameter LM vessel at 6 months, warranting the performance of a large-scale randomized trial.

Left main coronary artery stenosis: state-of-the-art

Patients with stenosis of the left main coronary artery present difficult challenges. The risks associated with this lesion have been known since the early days of angiography when patients were found to have increased mortality during follow-up. This information led to the general guidelines that surgical revascularization should be considered the treatment of choice in patients with significant left main coronary artery stenosis. Current advances in invasive cardiology have brought important information to the field. Intravascular ultrasound is now used routinely to evaluate angiographically indeterminate lesions with criteria now set forward as to what constitutes an indication for revascularization. Stents have even further dramatically changed the landscape. There are substantial issues, however, that need to addressed. These include the following: (1) the effect of specific lesion location on outcome - it is known that patients with distal bifurcation left main disease have worse outcome; (2) the potential for subacute thrombosis of the left main coronary artery; (3) the impact of left ventricular function and patient comorbidities irrespective of the degree and location of left main coronary artery stenosis; and (4) the risk-benefit ratio of stenting versus coronary artery bypass graft surgery. These issues are currently being addressed in two seminally important trials including the SYNTAX trial, which randomizes patients with left main and/or three-vessel disease to either coronary artery bypass graft surgery or a TAXUS drug-eluting stent. This trial is in the final stages of patient recruitment and will have important implications for the field. The other trial is the COMBAT trial, which is focused exclusively on left main coronary artery stenosis and randomizes patients with left main coronary artery disease either to a Sirolimus-eluting stent (Cypher, Johnson and Johnson Cordis, USA) or to coronary artery bypass graft surgery. The field of left main coronary artery disease continues to expand in terms of the evidence available for optimal patient evaluation and selection of treatment modalities.

The impact of cardiovascular risk factors on subclinical left main coronary artery disease: an intravascular ultrasound study

BACKGROUND

The impact of cardiovascular risk factors on subclinical but measurable left main coronary artery (LMCA) atherosclerosis is not well known.

METHODS

We analyzed 150 consecutive patients with first-time coronary artery disease presentation undergoing intervention of a left anterior descending coronary artery or left circumflex lesion with motorized intravascular ultrasound transducer pullback that included a nonstenotic LMCA. Framingham, PROCAM, and European SCORE risk assessments were determined in 107 patients <65 years of age (because the Framingham, PROCAM, and European SCORE studies excluded patients >65 years old). Intravascular ultrasound measurements were compared in patients with <10% vs 10% to 20% risk of events.

RESULTS

Plaque volumes were greater in patients with higher risk scores: P = .007 in patients with 10% to 20% PROCAM risk, P = .063 in patients with 10% to 20% Framingham risk, and P = .059 in patients with 10% to 20% SCORE risk (P = .059). The mean arc of LMCA calcium (12 degrees +/- 25 degrees overall) correlated with plaque volume (51 +/- 28 mm3, r = 0.30, P = .0001) and with the number of coronary risk factors (P = .048) and ranged from 0.28 degrees +/- 0.74 degrees in patients with 0 to 1 risk factors to 9.95 degrees +/- 21.55 degrees in patients with 2 to 4 risk factors to 19.38 degrees +/- 32.51 degrees in patients with 5 to 7 risk factors. Regression analysis showed obesity and age were the most important factors contributing to LMCA calcium.

CONCLUSION

Intravascular ultrasound measurable atherosclerosis in nonstenotic LMCA correlates with conventional primary coronary risk scores. Left main coronary artery calcium correlates both with LMCA plaque volume and risk factors. Thus, subclinical LMCA atherosclerosis may be a marker for events that are predicted by commonly used primary risk-assessment algorithms.

Clinical outcome in patients with intermediate or equivocal left main coronary artery disease after deferral of surgical revascularization on the basis of fractional flow reserve measurements

BACKGROUND

Correct assessment of the significance of left main stem lesions is of pivotal importance to the patient with coronary artery disease. On the basis of clinical and angiographic information alone, this evaluation often cannot be done reliably. Limited data suggest that coronary pressure-derived fractional flow reserve (FFR) supports decision making in equivocal left main disease.

METHODS

All patients presenting to our institution between June 1999 and June 2004 with intermediate left main coronary artery disease (40%-80% diameter stenosis by angiography), or in whom left main coronary disease was suspected but could not be quantified angiographically, were included in this prospective single-center follow-up study. If FFR was <0.75 along the left main stem, surgical revascularization was recommended; if FFR was >0.80, medical treatment or percutaneous coronary intervention elsewhere in the coronary tree was chosen. If FFR was in the "gray zone," between > or = 0.75 and < or = 0.80 treatment recommendation was dependent on additional individual criteria. Primary end points were freedom from death, myocardial infarction, any coronary revascularization procedure, and stroke.

RESULTS

Fifty-one patients (mean age 62.2 +/- 9.6 years, 41 male) were included. In 27 patients (53%), coronary artery bypass surgery was performed. The remaining 24 patients (47%) were treated nonsurgically. Mean follow-up was 29 +/- 16 months. Estimated survival after 4 years of follow-up was 81% among patients in the surgical group and 100% among patients in the nonsurgical group. Event-free survival was 66% in the surgical group and 69% in the nonsurgical group.

CONCLUSIONS

Fractional flow reserve is helpful to identify patients with intermediate left main disease in whom deferral of surgical revascularization is associated with excellent survival and low event rates.

A case of myocardial infarction due to acute left main coronary artery occlusion presenting with peculiar electrocardiographic changes

Myocardial infarction (MI) due to acute obstruction of the left main coronary artery (LMCA) occlusion is a medical emergency, requiring early and prompt diagnosis and revascularization, and unless it is treated, it will frequently result in cardiogenic shock, which has a high fatality rate. Our case focused on a patient, who was transferred to our hospital relatively late due to peculiar ECG. He had acute MI, and was in cardiogenic shock. ECG is the easiest diagnostic method in the early diagnosis of the acute coronary syndromes and in deciding on the early invasive intervention in the high risk group. Before he was sent to us, the patient had an ECG showing right bundle branch block (RBBB) and a AVR ST segment elevation. At the time of the urgent coronary angiography, it was noticed that the LMCA was totally occluded. This case has been presented in order to emphasize that peculiar changes might bring about devastating consequences as in our rare case, showing acute left main coronary artery occlusion, and ST segment elevation only in the AVR on the 12-lead ECG along with upward deflection of ST segment vector might be critical for accurate diagnosis.

Intravascular ultrasound-guided treatment for angiographically indeterminate left main coronary artery disease: a long-term follow-up study

OBJECTIVES

The purpose of this study was to evaluate the efficacy of an intravascular ultrasound (IVUS)-guided strategy for patients with angiographically indeterminate left main coronary artery (LMCA) disease.

BACKGROUND

The assessment of LMCA lesions using coronary angiography is often challenging; IVUS provides useful information for assessment of coronary disease.

METHODS

Intravascular ultrasound was performed on 121 patients with angiographically normal LMCAs to determine the lower range of normal minimum lumen area (MLA), defined as the mean - 2 SD. We conducted IVUS studies on 214 patients with angiographically indeterminate LMCA lesions, and deferral of revascularization was recommended when the MLA was larger than this predetermined value.

RESULTS

The lower range of normal LMCA MLA was 7.5 mm(2). Of the patients with angiographically indeterminate LMCAs, 83 (38.8%) had an MLA <7.5 mm(2), and 131 (61.2%) an MLA > or =7.5 mm(2). Left main coronary artery revascularization was performed in 85.5% (71 of 83) of patients with an MLA <7.5 mm(2) and deferred in 86.9% (114 of 131) of patients with an MLA > or =7.5 mm(2). Long-term follow-up (mean 3.3 +/- 2.0 years) showed no significant difference in major adverse cardiac events (target vessel revascularization, acute myocardial infarction, and death) between patients with an MLA <7.5 mm(2) who underwent revascularization and those with an MLA > or =7.5 mm(2) deferred for revascularization (p = 0.28). Based on outcome, the best cut-off MLA by receiver operating characteristic was 9.6 mm(2). Multivariate predictors of cardiac events were age, smoking, and number of non-LMCA vessels diseased.

CONCLUSIONS

Intravascular ultrasound is an accurate method to assess angiographically indeterminate lesions of the LMCA. Furthermore, deferring revascularization for patients with a minimum lumen area > or =7.5 mm(2) appears to be safe.

Relation Between Progression and Regression of Atherosclerotic Left Main Coronary Artery Disease and Serum Cholesterol Levels as Assessed With Serial Long-Term (≥12 Months) Follow-Up Intravascular Ultrasound

Background— The relation between serum lipids and risk of coronary events has been established, but there are no data demonstrating directly the relation between serum low-density lipoprotein (LDL) cholesterol and high-density lipoprotein (HDL) cholesterol versus serial changes in coronary plaque dimensions.

Methods and Results— We performed standard analyses of serial intravascular ultrasound (IVUS) studies of 60 left main coronary arteries obtained 18.3±9.4 months apart to evaluate progression and regression of mild atherosclerotic plaques in relation to serum cholesterol levels. Overall, there was (1) a positive linear relation between LDL cholesterol and the annual changes in plaque plus media (P&M) cross-sectional area (CSA) ( r =0.41, P <0.0001) with (2) an LDL value of 75 mg/dL as the cutoff when regression analysis predicted on average no annual P&M CSA increase; (3) an inverse relation between HDL cholesterol and annual changes in P&M CSA ( r =−0.30, P <0.02); (4) an inverse relation between LDL cholesterol and annual changes in lumen CSA ( r =−0.32, P <0.01); and (5) no relation between LDL and HDL cholesterol and the annual changes in total arterial CSA (remodeling). Despite similar baseline IVUS characteristics, patients with an LDL cholesterol level ≥120 mg/dL showed more annual P&M CSA progression and lumen reduction than patients with lower LDL cholesterol.

Conclusions— There is a positive linear relation between LDL cholesterol and annual changes in plaque size, with an LDL value of 75 mg/dL predicting, on average, no plaque progression. HDL cholesterol shows an inverse relation with annual changes in plaque size.

Long-term (three-year) outcomes after stenting of unprotected left main coronary artery stenosis in patients with normal left ventricular function

The purpose of this study was to analyze long-term follow-up information from patients treated with stenting for unprotected left main coronary artery (LMCA) stenosis. Stenting of unprotected LMCA stenosis is often performed in selected patients, but the long-term safety of this therapy is not yet established. Between January 1995 and September 2000, 270 consecutive patients with unprotected LMCA stenosis and normal left ventricular function who underwent treatment at 4 clinical centers were included in this study. Data were forwarded to the coordinating center using a standard case report form. The procedural success rate was 98.9%. There were no deaths, 3 stent thromboses, and 3 Q-wave myocardial infarctions during the hospitalization. Angiographic follow-up was performed in 237 patients (follow-up rate 87.8%), and the restenosis rate was 21.1%. The reference size was an independent predictor of binary restenosis (odds ratio 0.543, 95% confidence interval 0.308 to 0.957, p = 0.03). During the follow-up period (32.3 +/- 18.5 months), there were 20 deaths (8 cardiac, 12 noncardiac) and 5 nonfatal myocardial infarctions. Target and new lesion revascularizations were required in 45 (16.7%) and 31 (11.5%) patients, respectively. The cumulative probabilities free from major adverse cardiac events were 81.9 +/- 2.4%, 78.4 +/- 2.6%, and 77.7 +/- 2.7%, respectively, at 1, 2, and 3 years. Combined coronary artery disease and postprocedural minimal luminal diameter were the significant predictors of major adverse cardiac events. Thus, the long-term prognosis of patients after stenting of unprotected LMCA stenosis was favorable in selected patients with normal left ventricular function.

Elective stenting of unprotected left main coronary artery stenosis: effect of debulking before stenting and intravascular ultrasound guidance

OBJECTIVES

We sought to evaluate: 1) the long-term outcomes of 127 selected patients receiving unprotected left main coronary artery (LMCA) stenting; and 2) the impact of the debulking procedure before stenting and intravascular ultrasound (IVUS) guidance on their clinical outcomes.

BACKGROUND

The long-term safety of stenting of unprotected LMCA stenoses has not been established yet.

METHODS

A total of 127 consecutive patients with unprotected LMCA stenosis and normal left ventricular function were treated by elective stenting. The long-term outcomes were evaluated between two groups: IVUS guidance (n = 77) vs. angiographic guidance (n = 50); and debulking plus stenting (debulking/stenting; n = 40) vs. stenting only (n = 87).

RESULTS

Angiographic restenosis was documented in 19 (19%) of 100 patients. The lumen diameter after stenting was significantly larger in IVUS-guided group (p = 0.003). The angiographic restenosis rate was significantly lower in the debulking/stenting group (8.3% vs. 25%, p = 0.034). The reference artery size was the only independent predictor of angiographic restenosis. During follow-up (25.5 +/- 16.7 months), there were four deaths, but no nonfatal myocardial infarctions occurred. The survival rate was 97.0 +/- 1.7% at two years.

CONCLUSIONS

These data suggest that stenting of unprotected LMCA stenosis might be associated with a favorable long-term outcome in selected patients. Guidance with IVUS may optimize the immediate results, and debulking before stenting seems to be effective in reducing the restenosis rate. However, we need a large-scale, randomized study.

Factors predicting mortality in patients after myocardial infarction caused by left main coronary artery occlusion: significance of ST segment elevation in both aVR and aVL leads

Acute left main coronary artery obstruction is rare and most patients in this clinical setting die of sudden death or cardiogenic shock. During the past 8 years, we encountered 13 patients with acute myocardial infarction caused by total occlusion of the left main coronary artery (LMCA-AMI). Thus, we surveyed these patients, and attempted to elucidate helpful predictors related to the prognosis. Six of 13 patients with LMCA-AMI survived. Successful left coronary artery dilatation was achieved in all survivors (group S), and in 5 (71%) non-survivors (group non-S). The age was not different between the two groups. A past history of angina was confirmed in 83% of group S. while only in 29% of group non-S. Clinical findings such as time of onset of AMI, interval from the AMI onset to admission, elapsed period from the AMI onset to recanalization of LMCA and the value of CK on admission were not different between the two groups. However, cardiogenic shock occurred in only 1 patient (17%) in group S compared with 5 patients (71%) in group non-S. As emphasized in the literature, good collateral circulation to the left anterior descending artery was observed in 5 patients (83%) in group S, while not observed in group non-S. Electro cardiographically, ST elevation in the aVR lead was very characteristic. This finding was confirmed in 69% of the total patients. Noticeably, 5 out of 6 non-survivors (83%) showed ST elevation not only in leads aVR but also in the aVL lead. In addition to the absence of collateral circulation, this electrocardiographic finding, which obviously indicates the presence of extensive myocardial ischemia in the diseased heart, is a simple and important predictor suggesting a poor prognosis in LMCA-AMI patients.

Isolated bypass grafting of the left internal thoracic artery to the left anterior descending coronary artery: late consequences of incomplete revascularization

OBJECTIVE

Multiple strategies to achieve some degree of myocardial revascularization are available. In some, less complete revascularization is accepted to limit invasiveness. To examine the issues of incomplete revascularization, we assessed the long-term impact of additional non-left anterior descending coronary artery stenoses in patients undergoing only grafting of the left internal thoracic artery to the left anterior descending coronary artery.

METHODS

A total of 2067 patients underwent primary isolated grafting of the left internal thoracic artery to the left anterior descending coronary artery from 1971 to 1997. Of these, 26% and 13% had 2- and 3-system disease, respectively. Multivariable analyses of survival and reintervention were performed in the hazard function domain for 27,683 patient-years of follow-up (mean 14 +/- 6.7).

RESULTS

Survival was 99%, 88%, and 62% at 1, 10, and 20 years. Right coronary artery or left circumflex system disease of 50% or more (P =.02) and particularly high-grade (>/=70%) left circumflex (P =.01) and proximal right coronary artery disease (P =.01), as well as any degree of left main trunk stenosis (P <.0001), were associated with reduced long-term survival. Compared with 75% 20-year survival in patients with no non-left anterior descending disease, those with either left circumflex or left main trunk disease experienced a 44% survival, and those with proximal right coronary artery disease, 42%. The most common stated reason for incomplete revascularization was small vessel size. Freedom from reintervention was 89% and 65% at 10 and 20 years, respectively. High-grade left main trunk disease, but, in contrast, mid or distal disease of the right coronary artery, and not left circumflex disease, were risk factors for reintervention.

CONCLUSIONS

These findings call into question the long-term appropriateness of interventions whose strategy includes leaving unrevascularized segments in territories not in the distribution of the left anterior descending coronary artery.

Sudden death and cerebral anoxia in a young woman with congenital ostial stenosis of the left main coronary artery

We report a 36-year-old woman with ventricular fibrillation, subsequent sudden clinical cardiac death, and a prolonged brain anoxia. After a successful resuscitation coronary angiography revealed congenital ostial left main coronary artery (LMCA) stenosis. Surgical anastomosis of the left internal mammary artery (LIMA) to LAD led to a complete recovery. Postoperative electrophysiological examination, mainly programmed ventricular stimulation, failed to excite any rhythm disturbances. Cathet. Cardiovasc. Intervent. 48:67-70, 1999.

Variations of remodeling in response to left main atherosclerosis assessed with intravascular ultrasound in vivo

Histopathologic studies have demonstrated that vessels enlarge to compensate for an increase in plaque burden; this has been confirmed in vivo using intravascular ultrasound (IVUS). The initial studies suggested a biphasic course of lesion formation with (1) preservation of lumen dimensions up to a plaque burden of approximately 40%, and (2) luminal narrowing as plaque burden further increases. In this study, we used IVUS and angiography to assess the extent of left main (LM) atherosclerosis in 107 patients undergoing catheter-based procedures of the left anterior descending or left circumflex coronary arteries. Using IVUS, atherosclerotic plaques were found in all LM arteries, but only 26 (24%) had varying degrees of luminal narrowing on the angiogram. Nevertheless, there was an inverse relation (r = -0.62, p <0.0001) between the minimal lumen area and the plaque burden (i.e., plaque + media divided by total vessel area) that was not restricted to plaque burden values >40% (or >30%), but persisted at plaque burden values of 20% to 40%. In addition, LM arteries with a plaque burden <40% had a similar total vessel area as did LM arteries with a plaque burden > or =40% (22.9 +/- 6.1 vs 21.8 +/- 4.8 mm2, p = 0.30). These data suggest that lumen dimensions may not be preserved even if plaque occupies no more than 20% to 40% of the total vessel area. Thus, there is more variation in remodeling response during earlier stages of plaque accumulation within the LM artery than is commonly suggested.

Percutaneous treatment of protected and unprotected left main coronary stenoses with new devices: immediate angiographic results and intermediate-term follow-up

OBJECTIVES

We sought to evaluate the immediate angiographic results and intermediate-term follow-up after percutaneous treatment of left main coronary stenoses in the new device era.

BACKGROUND

Historically, balloon angioplasty of left main coronary stenoses has been associated with high procedural morbidity and poor long-term results. It is not clear whether new devices are more effective in this anatomic setting.

METHODS

Between July 1993 and July 1995, we performed initial left main coronary interventions on 46 patients (mean age 67 +/- 12 years, 26% women). Quantitative angiography was available for 42 of 46 interventions, and clinical follow-up was obtained for all patients at 1 month, 6 months and 1 year after initial revascularization.

RESULTS

Most interventions (42 of 46) were performed in patients with "protected" coronary stenoses to the left coronary system owing to the presence of one or more patent left main coronary grafts. Seventy-seven percent of screened patients were deemed unsuitable for repeat coronary artery bypass surgery. Procedures performed included stenting in 73% of patients (alone in 30% and after rotational atherectomy in 43%), rotational atherectomy in 58% (alone in 15% and before stenting in 43%), directional atherectomy in 4% and angioplasty alone in 7%. Initial procedural success was achieved in all interventions, with no deaths, myocardial infarctions (creatine kinase, MB fraction > 50 IU/liter) or emergent bypass surgery. Follow-up data to date (median duration 9 months, range 6 to 19) demonstrate a 98% overall survival rate and a 6-month event-free survival rate of 78% (six target vessel revascularizations [TVRs], four non-TVRs).

CONCLUSIONS

Treatment of protected left main coronary artery stenoses can be accomplished safely and effectively with new device technology. Intermediate-term follow-up demonstrates an acceptably low rate of death, myocardial infarction or repeat revascularization at 6 months and 1 year.