Prognostic Impact of Indeterminate Diastolic Function in Patients With Functionally Insignificant Coronary Stenosis

Background: Cardiac diastolic dysfunction is an independent predictor of mortality, regardless of left ventric-ular (LV) systolic function. However, the current guidelines that define cardiac diastolic dysfunction may un-derrate the clinical implications of those with indeterminate diastolic function. Objectives: We sought to evaluate the prognostic implications of indeterminate diastolic function on echocar-diography and its association with coronary microvascular dysfunction (CMD). Methods: A total of 330 patients without LV systolic dysfunction and significant epicardial coronary stenosis (fractional flow reserve > 0.80) were analyzed from a prospective registry. Cardiac diastolic dysfunction was defined according to 2 algorithms depending on the presence of myocardial disease. First, the presence of myocardial disease and evidence of elevated LV filling pressure indicated diastolic dysfunction. Second, dia-stolic function in those without myocardial disease was defined using echocardiographic parameters (E/e', e' velocity, tricuspid regurgitation velocity, and left atrial volume index). Patients who did not meet half of the available criteria were classified as having indeterminate diastolic function. Coronary microvascular dysfunc-tion was defined as coronary flow reserve < 2.0 and index of microcirculatory resistance $ 25 U. The primary outcome was cardiovascular death or admission for heart failure at 5 years. Results: Coronary flow reserve was lower in patients with indeterminate diastolic function compared with those with no diastolic dysfunction (3.5 +/- 1.6 vs 3.2 +/- 1.6, P = .002). The prevalence of CMD was also higher in patients with indeterminate diastolic function than in those with no diastolic dysfunction (10.6% vs 4.9%, P < .034). Patients with indeterminate diastolic function showed significantly higher risk of cardiovascular death or admission for heart failure than those without indeterminate diastolic function but not greater than those with definite diastolic dysfunction (cumulative incidence: 12.6%, 27.2%, and 32.7%, respectively, log-rank P < .001). Presence of CMD and elevated LV filling pressure (E/e' > 14) were independent predictors for cardiovascular death or admission for heart failure in patients with indeterminate diastolic function. Conclusions: Patients with indeterminate diastolic function on echocardiogram showed higher risk of cardio-vascular death or admission for heart failure than those with no diastolic dysfunction. Presence of CMD and elevated LV filling pressure were independent predictors for cardiovascular death or admission for heart failure among patients with indeterminate diastolic function. (J Am Soc Echocardiogr 2023;36:295-306.)