Does Grade I Diastolic Dysfunction Cause Enlarged Heart?
No, grade I diastolic dysfunction does not cause left ventricular hypertrophy or cardiomegaly—rather, the relationship is reversed: underlying cardiac structural abnormalities (such as LVH) cause diastolic dysfunction. Grade I diastolic dysfunction represents the earliest stage of impaired relaxation with normal left atrial pressures, and it is a consequence, not a cause, of cardiac remodeling. 1
Understanding the Causal Relationship
The critical distinction is that grade I diastolic dysfunction is a functional manifestation of underlying structural heart disease, not the cause of structural changes:
Grade I diastolic dysfunction is defined by impaired LV relaxation with normal left atrial pressure (LAP), characterized by an E/A ratio ≤0.8 with peak E velocity ≤50 cm/sec. 1
LV hypertrophy and structural cardiac disease precede and cause diastolic dysfunction, not the other way around. The 2016 ASE/EACVI guidelines explicitly state that "the finding of pathologic LV hypertrophy is consistent with diastolic dysfunction," indicating that LVH is the underlying substrate that produces the functional abnormality. 1
Patients in the earliest stage of diastolic dysfunction often have normal LA volume, which further supports that grade I dysfunction represents early functional impairment before significant structural cardiac enlargement occurs. 1
What Actually Causes LVH and Cardiomegaly
The conditions that cause cardiac enlargement are the same conditions that subsequently produce diastolic dysfunction:
Pressure overload states (hypertension, aortic stenosis) cause compensatory LVH, which then leads to impaired relaxation and diastolic dysfunction. 2
Hypertrophic cardiomyopathy demonstrates that the magnitude of LVH directly correlates with the severity of diastolic abnormalities—more extensive hypertrophy produces worse diastolic function. 2
Metabolic and infiltrative diseases (amyloidosis, storage diseases) cause both structural changes and diastolic dysfunction as parallel manifestations of the underlying disease process. 3
Clinical Progression Pattern
The natural history demonstrates that structural disease comes first:
Early disease typically presents with grade I diastolic dysfunction that progresses to grade II as disease severity advances. 1 This progression reflects worsening of the underlying structural abnormality, not that grade I dysfunction is causing further structural damage.
In hypertensive heart disease with LVH, patients develop grade I dysfunction initially, which may progress to pseudonormal filling patterns (grade II) as LAP becomes elevated. 1 The hypertension and resulting LVH are the primary pathology.
Diastolic dysfunction with normal ejection fraction is characterized by "increased resistance to filling with increased filling pressures" in the context of underlying structural disease, not as an independent cause of cardiac enlargement. 4
Important Clinical Caveats
When evaluating patients with grade I diastolic dysfunction:
Always search for the underlying cause of the diastolic dysfunction rather than attributing cardiac structural changes to the dysfunction itself. Screen for hypertension, valvular disease, infiltrative processes, and genetic cardiomyopathies. 1, 3
A normal LA volume does not exclude diastolic dysfunction but does indicate that chronic elevation of filling pressures has not yet occurred—this is typical of grade I dysfunction. 1
Grade I dysfunction can exist with elevated LVEDP despite normal mean LAP, representing the earliest hemodynamic alteration, but this still does not cause structural enlargement. 5
Serial echocardiography is necessary to monitor both the structural disease and the functional consequences (diastolic dysfunction), recognizing that treating the underlying cause may improve both. 6, 3