Which vascular condition can result in decreased blood pressure in the left arm compared to the right?

Decreased blood pressure in the left arm compared to the right can occur due to various vascular conditions, each affecting blood flow and pressure in different ways.

Thoracic outlet syndrome can lead to compression of blood vessels and nerves as they pass through the thoracic outlet, potentially impacting blood flow to the arm and causing a noticeable difference in blood pressure between the arms.

Subclavian artery stenosis, which is a narrowing of the subclavian artery, can directly reduce blood flow to the affected arm, typically leading to lower blood pressure readings in that arm compared to the other arm.

Aortic coarctation involves a narrowing of the aorta that can cause differential blood pressure readings in the upper body. If the coarctation occurs distal to the left subclavian artery, the left arm may experience lower blood pressure due to reduced perfusion.

Considering these explanations, it's clear that all these conditions can lead to decreased blood pressure in one arm compared to the other, which is why the answer encompasses all of the provided options.