Which Blood Vessel Blockage Causes an Inferior Wall Myocardial Infarction?

An inferior wall myocardial infarction (MI) typically occurs due to the occlusion of either the right coronary artery (RCA) or the left circumflex artery (LCX). The exact vessel involved largely depends on the coronary artery dominance pattern of the individual. When a coronary artery becomes blocked, it can lead to ischemia and subsequent necrosis of the corresponding myocardial tissue. Below are the two main scenarios associated with inferior wall MI:

Right Dominant Coronary Anatomy

In the majority of people, especially among the Asian population, the coronary circulation follows a right-dominant pattern. In this configuration, the right coronary artery supplies blood not only to the right ventricle but also to the inferior and posterior walls of the left ventricle. When the RCA becomes occluded, it can result in an inferior wall MI, often accompanied by posterior wall involvement and, in some cases, right ventricular infarction as well.

Left Dominant Coronary Anatomy

Conversely, in individuals with a left-dominant coronary system, the left circumflex artery supplies the lateral and high lateral regions of the left ventricle, as well as the inferior and posterior walls. Occlusion of the LCX can lead to myocardial infarction in these areas, including the high lateral, inferior, and posterior walls of the heart.

Diagnostic Considerations and Clinical Implications

Accurate diagnosis of the occluded vessel is crucial for effective treatment planning. To determine the exact location and extent of the infarction, an 18-lead ECG is often recommended. This extended ECG can detect associated infarctions in other regions of the heart that may not be apparent on a standard 12-lead ECG.

For instance, if right ventricular involvement is detected, it strongly suggests that the right coronary artery is the culprit vessel. On the other hand, if there is evidence of high lateral wall infarction, the left circumflex artery is more likely to be responsible. Identifying the affected artery helps guide interventional strategies such as percutaneous coronary intervention (PCI) or coronary artery bypass grafting (CABG), ultimately improving patient outcomes and reducing mortality risk.