Echocardiographic diastolic indices and the ambulatory heart rate profile in preserved ejection fraction: implications for pre-exercise assessment

Aims: In patients with preserved ejection fraction, the relationship between routinely available echocardiographic indices and the ambulatory heart rate (HR) profile is not well defined. This study aimed to examine the association between echocardiographic diastolic and structural indices and the 24 h ambulatory (Holter) HR profile, with relevance to pre-exercise assessment. Methods: This single-center, retrospective study evaluated 300 adults with preserved left ventricular ejection fraction (LVEF ≥50%) who underwent both transthoracic echocardiography and 24 h Holter monitoring. The early-to-late diastolic mitral inflow velocity ratio (E/A), left atrial (LA) diameter, and pulmonary artery systolic pressure (PASP) were analyzed against the maximum, minimum, and mean HR and the HR range (maximum minus minimum), a descriptive index of daily HR behavior rather than a measure of exercise chronotropic reserve. Group comparison by E/A pattern, Spearman correlation, and multivariable linear regression were performed. Results: The HR range was higher in the E/A ≥1 group than in the E/A <1 group (median 68 versus 55 bpm; p<0.001). The HR range correlated positively with E/A (r=0.33) and negatively with LA diameter (r=-0.28) and PASP (r=-0.21) (all p<0.001). The minimum HR showed no meaningful correlation. After adjustment for age, gender, atrial fibrillation, and rate-limiting medication, E/A (B=12.62; standardized β=0.261; p<0.001) and LA diameter (B=-7.30; standardized β=-0.185; p=0.001) remained independent correlates of the HR range. The model explained approximately 21% of the variance (R²=0.211). Conclusion: In patients with preserved ejection fraction, the E/A ratio and LA diameter are independently associated with the ambulatory HR range, but not with the resting HR. The HR range is not a validated substitute for chronotropic reserve derived from cardiopulmonary exercise testing, and LA diameter does not replace LA volume index as a contemporary marker of diastolic burden. These hypothesis-generating findings require prospective validation.