Once Physicians and Clinicians as well as Research Scientists began looking at OI as a whole-body collagen disorder rather than just a bone disease. The severity of the collagen corruption became clearer and more disturbing.
The important caveat: most OI patients will never experience severe cardiac disease, and risk varies by OI type/severity. However, the literature over the last ~25 years points to a fairly consistent group of cardiovascular problems worth watching for. Below is my “top 10” based on frequency, clinical importance, and repeated appearance in cohort studies, reviews, and case series.
1. Mitral Valve Regurgitation (Leaky Mitral Valve)
Probably the most repeatedly described cardiac abnormality in adults with OI.
Because type I collagen is an important structural component of heart valves, the valve tissue can become more lax or structurally abnormal, allowing blood to leak backward.
Symptoms to watch for
Shortness of breath with exertion
Fatigue that seems disproportionate
Palpitations
New heart murmur
Swelling in legs/ankles in advanced cases
Why it matters in OI
Several studies found mitral regurgitation (MR) is significantly more common in OI than controls, especially in adulthood. Left-sided valves seem preferentially affected.
Sources: Springer/Calcified Tissue International systematic review (2024); PubMed cardiovascular complications review
2. Aortic Valve Regurgitation (Leaky Aortic Valve)
Another repeatedly reported issue.
The aortic valve may not close tightly, allowing blood to flow backward into the heart after each beat.
Symptoms
Fatigue
Reduced exercise tolerance
Breathlessness
“Bounding pulse”
Awareness of heartbeat when lying down
Closely related to #1, aortic valve disease is a persistent finding across decades of research. Adults with OI have presented with aortic insufficiency due to dilatation of the aortic root for which none of the usual causes is apparent, suggesting that in OI, as in other heritable disorders of connective tissue, cardiovascular defects may play a dominant role in the natural history of the disease process. (AHA Journals)
Why it matters
Danish cohort work and systematic reviews show aortic regurgitation (AR) appears more common in OI than in the general population.
Source: American Heart Association / Circulation journal
3. Aortic Root Dilation
This is probably the “classic” cardiovascular finding in OI literature.
The portion of the aorta nearest the heart may become enlarged because collagen defects weaken the vessel wall.
Symptoms
Usually none early on — this is why it is easy to miss.
Red flags
Chest pain
Unexplained shortness of breath
Sudden severe pain (emergency)
Why it matters
This finding has been reported for decades and remains one of the strongest cardiovascular associations in OI. Older studies estimated rates around 12–30%, though clinically severe enlargement appears uncommon in many adults. This is one of the most consistently documented structural abnormalities. More recent studies reported small but statistically significant differences in aortic diameters compared to matched controls. Vascular aneurysms and dissections have been reported in people with OI; however, the overall prevalence of aneurysms is unknown and the risk for dissections is not well understood.
Sources: (Oxford Academic) Aortic root dimensions correlate with disease severity of OI. (International Journal of Cardiology) , Journal of Bone and Mineral Research (2025); International Journal of Cardiology (2025)
4. Atrial Fibrillation (AFib) and Other Atrial Arrhythmias
This is newer in the literature and especially important.
Recent studies suggest atrial fibrillation may occur more frequently in OI adults than controls.
Symptoms
Fluttering heartbeat
Skipped beats
Racing pulse
Fatigue
Dizziness
Reduced stamina
Although it seems rather obvious why this would be important a major mortality concern backed by large registry data. OI patients have an increased risk of heart failure, increased risk of atrial fibrillation or flutter, and increased risk of aortic and mitral valvulopathies.
Why it matters
AFib raises stroke risk and can quietly worsen fatigue or shortness of breath. Additionally, there may be a problem with 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.
SOURCES: ScienceDirect / Danish nationwide register-based cohort study (2016) A 2024 systematic review found atrial fibrillation appears more prevalent in OI populations than controls.
5. Heart Failure (Usually Secondary to Valve Disease)
In an OI patient, heart failure is often not primary heart muscle failure—it tends to occur after years of valve disease or chronic cardiovascular strain.
Symptoms
Breathlessness
Reduced exercise tolerance
Swelling in legs
Trouble lying flat
Fatigue
Why it matters
Population studies increasingly suggest heart failure rates are elevated in OI versus controls.
That being said one of the MOST dangerous issues associated with Heart Failure is the fact that the patient could be have an attack, and not be aware that's what it is.
Source: ScienceDirect / Danish nationwide register-based cohort study (2016)
6. Hypertension (High Blood Pressure)
This one surprised researchers. OI patients appear to have higher rates of hypertension in some cohort studies.
Why it matters in OI
High blood pressure may worsen:
Aortic enlargement
Valve stress
Cardiovascular remodeling
Symptoms
Usually none—another silent problem.
I rank this higher on the list than many folks might due to the fact that “high blood pressure” is such a common issue in America today that many folks choose to ignore it. More prevalent in OI patients but still not fully understood mechanistically. People with OI appear to be more likely to have hypertension and atrial arrhythmias. Unfortunately since hypertension is common and multifactorial, with no known association to OI or collagen type I, many Physicians and Clinicians do not support the connection in the patient. further research is needed to elucidate its relation to OI. (Springer)
Source: Springer/Calcified Tissue International systematic review (2024)
Recent systematic review evidence suggests hypertension may be more prevalent in OI populations.
6a. Pulmonary Hypertension
I'm listing this as a subset of 6, although they are distinct issues, due to their naming schema they are often confused as being related or associated with each other. Driven by a combination of skeletal deformity and intrinsic collagen defects in the vasculature. Right ventricular and pulmonary artery dimensions in OI patients were higher than in control groups, and indirect evidence of pulmonary hypertension has been documented — though several studies report involvement of the left side of the heart and the aortic root as the most prevalent abnormalities, the right side of the heart can be involved as well. An underappreciated but well-documented problem, particularly in moderate-to-severe OI. OI was found to be an independent risk factor for right ventricular systolic and diastolic dysfunction. Cardiac symptoms and ECG changes are common among patients with OI, and both RV and LV systolic and diastolic function appear to be impaired in patients with OI compared with normal individuals. (ScienceDirect)
This one is easy to miss because it often starts with the lungs and rib cage.
In moderate/severe OI:
chest wall deformity
scoliosis
restrictive lung disease
can place chronic strain on the right side of the heart.
Symptoms
Shortness of breath
abdominal swelling
Reduced endurance
abdominal discomfort
Dizziness
belt level (waistband) tightness
Fatigue
This issue is increasingly discussed because morbidity and mortality in OI are strongly linked to cardiovascular + pulmonary interactions, not bones alone.
Source: ScienceDirect — Norwegian national OI registry study of 99 adults (2015) PubMed Central),
PMC cardiovascular involvement study; Oxford Academic / Human Molecular Genetics (2012)
7. Right Ventricular Dysfunction
An underappreciated but well-documented problem, particularly in moderate-to-severe OI. OI was found to be an independent risk factor for right ventricular systolic and diastolic dysfunction. Cardiac symptoms and ECG changes are common among patients with OI, and both RV and LV systolic and diastolic function appear to be impaired in patients with OI compared with normal individuals. (ScienceDirect)
Source: ScienceDirect — Norwegian national OI registry study of 99 adults (2015)
8. Structural/Myocardial Dysfunction (“Subclinical Heart Weakness”)
Some newer echocardiographic studies suggest OI patients may have subtle abnormalities in how the heart muscle contracts or relaxes, even before obvious symptoms appear.
Think of it as the heart becoming mechanically less efficient because collagen exists in the cardiac scaffolding too.
Symptoms
Often none early.
Later:
Fatigue
Reduced endurance
Exertional breathlessness
The literature increasingly refers to this as subclinical myocardial dysfunction.
9. Congenital Heart Defects (Less Common, But Overrepresented)
These are present from birth and seem somewhat more common in pediatric OI cohorts. While not as common as acquired cardiac issues, congenital defects appear at a higher-than-expected rate. Congenital heart defects were identified in 13% of OI patients studied, most commonly atrial septal defect (ASD) and patent ductus arteriosus (PDA).Cardiovascular findings including atrial septal defects have been reported in OI, alongside valvular insufficiency, aortic root dilation, and septal and posterior left ventricular wall thickening.
Examples include:
Atrial septal defect (ASD)
Patent ductus arteriosus (PDA)
More commonly reported in moderate/severe pediatric OI.
Recent pediatric data found congenital defects in roughly 13% of one OI cohort, especially ASD and PDA.
SOURCES: (International Journal of Cardiology) ,(PubMed Central)
10. Cardiopulmonary Strain
This one is easy to miss because it often starts with the lungs and rib cage.
In moderate/severe OI:
chest wall deformity
scoliosis
restrictive lung disease
can place chronic strain on the right side of the heart.
Symptoms
Shortness of breath
Reduced endurance
Dizziness
Fatigue
This issue is increasingly discussed because morbidity and mortality in OI are strongly linked to cardiovascular + pulmonary interactions, not bones alone.