Comparison of location of "culprit lesions" in left anterior descending coronary artery among patients with anterior wall ST-segment elevation myocardial infarction having ramus intermedius coronary arteries versus patients not having such arteries

The Ramus Intermedius: A Bridge to Survival in the Setting of Triple-Vessel Total Occlusion

Coronary artery disease continues to remain the leading cause of mortality worldwide. Coronary blood supply is provided through the right and left main coronary arteries. The left main coronary artery (LMCA) in turn gives rise to the left anterior descending (LAD) and left circumflex (LCX) arteries. In some cases, LMCA may trifurcate into the ramus intermedius (RI) in addition to the LAD and LCX arteries. Atherosclerotic plaque formation and rupture with subsequent clot formation and occlusion of coronary arteries are the underlying mechanisms of myocardial infarction. Though the clinical implications of the presence of ramus intermedius (RI) are controversial some data suggest that the RI is associated with an increased risk of atherosclerotic plaque formation in the LMCA and the proximal LAD. Conversely, it has been proposed that the RI provides an additional collateral source of blood supply to the myocardium and may potentially contribute to improved survival. Case reports tout the benefits of RI, specifically in the setting of multivessel coronary artery occlusions. Whether it increases the risk of atherosclerotic plaque formation or whether it is protective has yet to be determined. We present a case of a 58-year-old male who presented with acute coronary syndrome and cardiogenic shock due to total ostial occlusion of LAD. The patient had also chronic total occlusions of the right coronary artery and LCX but a patent RI, which was the only source of blood supply to the myocardium and practically determined the patient's survival. Additionally, we performed a literature review to identify similar cases, to support RI's potentially protective role in enhancing survival.

Coronary computed tomography angiography study on the relationship between the Ramus Intermedius and Atherosclerosis in the bifurcation of the left main coronary artery

OBJECTIVE

This study aimed to explore the relationship between the ramus intermedius (RI) and atherosclerosis in the bifurcation of the left coronary artery (LCA).

METHODS

Screening patients who underwent CCTA from January to September 2021, 100 patients with RI (RI group) and 100 patients without RI (no-RI group) were randomly enrolled, Evaluation of RI distribution characteristics and left main coronary artery(LM),Left anterior descending branch(LAD),left circumflex branch(LCX) proximal segment plaque distribution, measurement of LAD-LCX bifurcation angle(∠LAD-LCX),Comparison of the three distribution characteristics with the incidence of plaques in the left main trunk bifurcation area (LM, LAD, LCX) between groups and within the RI group.

RESULTS

The difference in the incidence of plaques in the proximal LCX and the LM between the RI group and the no-RI group were not statistically significant (P > 0.05). The incidence of plaques in the proximal LAD in the RI group was significantly higher than that in the non-RI group (77% versus 53%, P < 0.05). However, there was no statistically significant difference between the two groups after PSM. A univariate logistic regression analysis revealed that an RI was a risk factor for plaque formation in the proximal LAD (P < 0.001), and a multivariate logistic regression analysis revealed that an RI was not an independent risk factor for plaque formation in the proximal LAD (P > 0.05). When compared within the RI group, the difference in the incidence of plaques in the proximal segment of LAD, the proximal segment of LCX, and the LM among the different distribution groups of RI was not statistically significant, respectively (P > 0.05).

CONCLUSION

RI is not an independent risk factor for atherosclerosis in the left coronary artery bifurcation zone, but it may indirectly increase the risk of atherosclerosis in the proximal segment of the LAD.

Effect of Presence of Ramus Intermedius Artery on Location of Culprit Lesions in Acute Left Circumflex Coronary Artery Occlusion

BACKGROUND AND AIM

Coronary artery anatomy frequently affects location of atherosclerotic plaques and subsequent culprit lesions. We sought to clarify whether presence or absence of Ramus Intermedius coronary artery (RI) would affect location of culprit lesions in acute left circumflex (LCX) coronary artery occlusion.

METHODS

The study included 180 patients, 100 with a diagnosis of non-ST elevation myocardial infarction (NSTEMI) and 80 with ST elevation myocardial infarction (STEMI). All culprit lesions were located in the LCX coronary artery. RI group included 45 patients and the No RI group included 135 patients.

RESULTS

Culprit LCX lesions were similarly located at a comparable distance from LCX ostium in both groups and the presence of RI was not associated with significantly more proximally located culprit LCX lesions (34.7 ± 15.2 mm compared to 30.8 ± 17.9 mm respectively, p > 0.05). The frequency distribution of culprit lesions' distance from LCX ostium showed no significant difference between both groups in any of the segments studied (10 mm each). There was no significant difference between both groups regarding markers of myocardial necrosis size as cardiac biomarkers (peak cardiac troponin-T 1077.4 ± 361.2 pg/dl vs 926 ± 462.2 pg/dl respectively, p = 0.13), (peak creatine kinase-MB 232.2 ± 81 ng/dl vs 194.7 ± 99.2 ng/dl respectively, p = 0.07) or left ventricular ejection fraction (EF 46.3 ± 6.3% vs 48.3 ± 8.3% respectively, p = 0.76).

CONCLUSION

Presence of RI coronary artery, as an additional flow divider, may not be associated with more proximal culprit lesions, compared to its absence, in cases of acute LCX coronary artery occlusion. Possible underlying pathophysiologic mechanisms remain to be clarified.