Table 1.

Cardiovascular complications of hypothyroidism.

CARDIOVASCULAR SYSTEM	SEQUELAE OF HYPOTHYROIDISM	PATHOGENESIS
Cardiac function	↓ Systolic and diastolic function ↓ Cardiac output	➢Altered transcription of myocyte contractility and relaxation genes ➢Alteration of cardiac ion channels ➢↓ Peripheral oxygen consumption and requirements ➢↓ Erythropoietin and erythropoiesis → ↓ Blood volume
Endothelial function	Arterial stiffness Impaired vasoreactivity ↑ Systemic vascular resistance Diastolic hypertension	➢↓ Vasodilator synthesis and activity ➢↓ Tissue thermogenesis and metabolic activity
Metabolic status	↑ Total cholesterol	➢↓ Catabolism of cholesterol into bile by cholesterol 7-alpha-hydroxylase enzyme
	↑ LDL	➢↓ Hepatic LDL receptor density and activity → ↓ Fractional clearance of LDL
	↑ Triglycerides
Vascular disease	Atherosclerosis	➢Dyslipidema ➢Hyperhomocysteinemia ➢Hypertension
	Vascular calcification	➢↓ Vascular calcification inhibitors: matrix Gla and klotho
Cardiac conduction	Ventricular arrhythmia	➢Changes in cardiac ion channel expression → Prolongation of QT interval