Sometimes you just need some additonal details to make it absolutely clear, not to mention heart issues are almost always serious more often than they aren't.

Not to mention if your primary care provider is NOT a cardiac specialist, this level of detail could help all of you come to a common consensus
sooner, rather than later.

How the Collagen Defect Directly lead to Cardiac Disease


This is the fundamental "why" behind everything on the previous list, and it's more direct than most people realize.


Collagen Type I Is Literally Inside Your Heart

Heart valves, chordae tendineae, annuli fibrosi, and the interventricular septum all contain collagen type I. Approximately 74% of the collagen content of the mitral valve is collagen type I. The chordae tendineae have a central part comprised of compact collagen. Collagen fibers in the ventricular myocardium contribute to the tensile stiffness and maintain the architecture of the myocytes. The aorta and most arteries are rich in both type III and type I collagen. (ScienceDirect)

This means the defect in OI isn't just about bones — it's woven into the very structure of the heart's working parts. In the cardiovascular system, type I collagen provides tensile strength and structural integrity to the myocardium, cardiac valves, chordae tendineae, and great vessels. The disruption of collagen synthesis in OI may therefore predispose these patients to cardiovascular complications, similar to other connective tissue disorders like Marfan and Ehlers-Danlos syndrome. (International Journal of Cardiology)


The Myocardium Itself Is Affected

A decrease in collagen is associated with a more compliant ventricle, which results in increased LV diastolic internal diameters and volume. Type I collagen contributes to the stiffer and rigid property of the myocardium. (nih) In plain terms: when the collagen scaffolding of the heart muscle is defective, the heart chambers stretch and dilate more than they should, altering how efficiently the heart contracts and relaxes.


It's Not Just Secondary to Bone Problems


This is a crucial point that research has recently clarified. Data obtained from human OI patients and mouse models provide novel evidence for primary effects of type I collagen mutations on the heart and lung — representing a bone-independent vicious cycle of heart dysfunction, including hypertrophy, loss of myocardial matrix integrity, and pulmonary hypertension. (Oxford Academic) Bisphosphonates reduce fractures in OI mice but do not improve survival, strongly suggesting the cardiac damage is happening independently of the skeletal disease.


The Electrical System Is Also Vulnerable


An explanation for the connection between OI and arrhythmias may be the role of collagen type I as a component of the extracellular matrix of the cardiac conduction system, which ensures its insulation from the rest of the cardiac tissue. Collagen integrity may be required for efficient transduction of electrical signals. (PubMed Central) So even the heart's electrical wiring depends on healthy collagen — explaining why arrhythmias show up in OI patients.


Severity of Mutation = Severity of Cardiac Risk


The cardiovascular abnormalities appear to be correlated to COL1A1 mutation and defects of type I collagen, which expands understanding of the cardiac phenotypes of OI patients. (PubMed Central) The worse the collagen defect genetically, the more cardiac structures are compromised — which is why severe OI types carry higher cardiovascular risk.