Thyroid hormone is very important for normal heart rate and cardiovascular function.Due to hypothyroidism heart muscle become weakened so this cause a problem in cardiac muscle contraction and relaxation.For this Heart can't pump properly so it can't eject the amount of blood it should be ejected.For this reason a serious problem diastolic dysfunction may occur.In addition, hypothyroidism reduces the amount of nitric oxide in the lining of the blood vessels, causing them to stiffen.

Hypothyroidism is a major cause of heart disease because homocysteine levels are higher in people with hypothyroidism. Oddly, homocysteine levels aren't lower in people with hyperthyroidism.

Homocysteine causes damage to the inner arterial lining, or endothelium. It can initiate or worsen arteriosclerosis, the thickening/hardening/loss of elasticity of the the arterial walls. A link has also been established between high homocysteine levels and congestive heart failure (CHF).

Wow, you are on a roll here!

Yes, hypothyroidism leads to elevations of pro-inflammatory homocysteine.

Development of arterial plaque is irrelevant of cholesterol levels. In fact, about 50% of people who die of heart attacks have normal to low levels of cholesterol. And low cholesterol is an even more significant risk for having a heart attack.

Cholesterol is actually a healing agent for the body and floods injured areas of the body to assist with repair. Since elevated homocysteine damages the arterial lining this leads to arterial wall inflammation. In response the cholesterol floods the injured area again to assist with healing. If the source of inflammation is not removed the cholesterol keeps flooding the area leading to the build up of plaque.

Thanks. I enjoy your questions. I spent years in the medical field and it truly is my passion. Besides that, it's really not about knowing the answer. It's about knowing where to find the answer.