Left main coronary artery disease: A review of the spectrum of noninvasive diagnostic modalities

Living on a Thread: A Case of Critical Left Main Coronary Artery Disease With an Unusual Presentation

The left main disease is significant stenosis of the left coronary artery, which is responsible of supplying blood to a major portion of the left ventricle. In this report, we describe a unique case of critical left main disease with a special clinical presentation.

A 66-year-old male with insignificant past medical history presented with dyspepsia. Patient presented twice to the emergency department seeking for help for his persistent complaint. During his second visit, patient was diagnosed with type one myocardial infarction and underwent coronary angiography which showed 90% stenosis in the left main coronary artery. Patient underwent successful coronary artery bypass grafting and was sent home.

This case is a unique representation of type 1 myocardial infarction as the peak troponin I level does not correlate with the extent of the myocardium being jeopardized. A big portion of the heart is at risk of injury with the 90% stenosis found in this patient’s left main coronary artery, yet the peak troponin I level is minimum. This report provides a possible explanation of the discrepancy between the peak troponin I level and the extent of the myocardium being jeopardized and describes a common yet easily missed clinical presentation of acute coronary syndrome.

Left main disease is a relatively uncommon presentation of acute coronary syndrome, with potentially serious detrimental consequences. Discrepancies do occur among patients of critical left main disease, and promptly diagnosing and managing is of great importance.

Assessment of arteriosclerosis based on multiscale cross approximate entropy of human finger pulse wave

BACKGROUND: Arteriosclerosis is one of the diseases that endanger human health. There is a large amount of information in pulse wave signals to reflect the degree of arteriosclerosis. OBJECTIVE: The degree of arteriosclerosis is assessed by analyzing pulse wave signal and calculating multi-scale entropy values. METHODS: A method based on the multiscale cross-approximate entropy of the pulse wave of the human finger is proposed to assess the degree of arteriosclerosis. A total of 86 subjects were divided into three groups. The data of 1000 pulse cycles were selected in the experiment, and the multiscale cross-approximate entropy was calculated for the climb time and pulse wave peak interval. Independent sample t-test analysis gives the small-scale cross-approximate entropy of the two time series of climb time and pulse wave peak interval as p< 0.001 in Groups 1 and 2. The large-scale cross-approximate entropy of the two time series of climb time and pulse wave peak interval is p< 0.017 in Groups 2 and 3. RESULTS: Using the proposed algorithm, the results showed that the small-scale cross-approximate entropy of climb time and pulse wave peak interval could reflect the degree of arteriosclerosis in the human body from the perspective of autonomic nerve function. The large-scale cross-approximate entropy of climb time and pulse wave peak interval confirmed the effect of diabetes on the degree of arteriosclerosis. CONCLUSIONS: The results demonstrate the multiscale cross-approximate entropy is a comprehensive index to evaluate the degree of human arteriosclerosis.

Predictors of Left Main Coronary Artery Disease in the ISCHEMIA Trial

BACKGROUND

Detection of ≥50% diameter stenosis left main coronary artery disease (LMD) has prognostic and therapeutic implications. Noninvasive stress imaging or an exercise tolerance test (ETT) are the most common methods to detect obstructive coronary artery disease, though stress test markers of LMD remain ill-defined.

OBJECTIVES

The authors sought to identify markers of LMD as detected on coronary computed tomography angiography (CTA), using clinical and stress testing parameters.

METHODS

This was a post hoc analysis of ISCHEMIA (International Study of Comparative Health Effectiveness With Medical and Invasive Approaches), including randomized and nonrandomized participants who had locally determined moderate or severe ischemia on nonimaging ETT, stress nuclear myocardial perfusion imaging, or stress echocardiography followed by CTA to exclude LMD. Stress tests were read by core laboratories. Prior coronary artery bypass grafting was an exclusion. In a stepped multivariate model, the authors identified predictors of LMD, first without and then with stress testing parameters.

RESULTS

Among 5,146 participants (mean age 63 years, 74% male), 414 (8%) had LMD. Predictors of LMD were older age (P < 0.001), male sex (P < 0.01), absence of prior myocardial infarction (P < 0.009), transient ischemic dilation of the left ventricle on stress echocardiography (P = 0.05), magnitude of ST-segment depression on ETT (P = 0.004), and peak metabolic equivalents achieved on ETT (P = 0.001). The models were weakly predictive of LMD (C-index 0.643 and 0.684).

CONCLUSIONS

In patients with moderate or severe ischemia, clinical and stress testing parameters were weakly predictive of LMD on CTA. For most patients with moderate or severe ischemia, anatomical imaging is needed to rule out LMD. (International Study of Comparative Health Effectiveness With Medical and Invasive Approaches [ISCHEMIA]; NCT01471522).

Predictors and 3-year outcomes of compromised left circumflex coronary artery after left main crossover stenting

BACKGROUND

There are few predictors of decreased fractional flow reserve (FFR) in the left circumflex coronary artery (LCx) after left main (LM) crossover stenting.

OBJECTIVES

We aimed to determine the predictors for low FFR at LCx and possible treatment strategies for compromised LCx, together with their long-term outcomes.

METHODS

Altogether, 563 patients who met the inclusion criteria were admitted to our hospital from February 2015 to November 2020 with significant distal LM bifurcation lesions. They underwent single-stent crossover percutaneous coronary intervention (PCI) under intravascular ultrasound (IVUS) guidance with further LCx intervention based on the measured FFR.

RESULTS

The patients showed significant angiographic LCx ostial affection post-LM stenting, but only 116 (20.6%) patients had FFR < 0.8. The three-year composite major adverse cardiac events (MACE) rates were comparable between the high and low FFR groups (16.8% vs. 15.5; p = 0.744). In a multivariate analysis, low FFR at the LCx was associated with post-stenting minimal luminal area (MLA) of LCx (odds ratio [OR]: 0.032, p < .001), post-stenting LCx plaque burden (OR: 1.166, p < .001), poststenting LM MLA (OR: 0.821, p = .038), and prestenting LCx MLA (OR: 0.371, p = .044). In the low FFR group, those with compromised LCx managed with drug-eluting balloon had the lowest three-year MACE rate (8.1%), as compared to either those undergoing kissing balloon inflation (KBI) (17.5%) or stenting (20.5%) (p = 0.299).

CONCLUSION

Unnecessary LCx interventions can be avoided with FFR-guided LCx intervention. Poststenting MLA and plaque burden of the LCx, and main vessel stent length are poststenting predictors of low FFR.

Myocardial perfusion imaging in patients with unprotected left main disease

BACKGROUND

The management of patients with unprotected left main (LM) coronary artery disease remains challenging, with recent data casting a shadow of doubt on the safety of percutaneous coronary intervention. We aimed at describing the features of patients undergoing myocardial perfusion imaging (MPI) subsequently found to have LM disease.

METHODS

We queried our institutional database for subjects without prior revascularization or myocardial infarction (MI), who had undergone MPI followed by invasive coronary angiography within 6 months, comparing those with evidence of angiographically significant LM disease (i.e. diameter stenosis ≥50%) to those without significant coronary artery disease (CAD), or those with CAD not involving LM. Baseline, stress and imaging features were systematically collected and analyzed, and clinical outcomes (death, myocardial infarction, revascularization) sought.

RESULTS

We included a total of 74 patients with LM disease, which were compared with 70 without CAD, and 920 with significant CAD not involving LM. MPI was remarkably safe in all subjects, and significant differences were found for several features, but particularly so for ST change, rate pressure product, and left ventricular ejection fraction (all P<0.05). Most patients with LM disease had moderate or severe ischemia, and the apical, lateral and inferior regions were the most sensitive ones. Clinical outcomes after an average of 35 months were worse in patients with LM disease than in subjects with significant CAD not involving LM, albeit non-significantly, possibly in light of the higher use of coronary artery bypass grafting.

CONCLUSIONS

MPI is safe and informative in patients with LM disease, and multidimensional appraisal of MPI results may guide decision-making on top of providing prognostic detail and warranty period.