Early postoperative "grey zone" gradients following aortic valve replacement surgery: the clinical course and...

Surgeons frequently encounter early postoperative intermediate transvalvular gradients (20-40 mmHg, "grey zone") after aortic valve replacement (AVR). We investigated whether these gradients compromise short-term clinical stability or represent a transient, clinically compensated phase, marked by systemic mechanical stress.

We retrospectively evaluated 141 consecutive isolated AVR patients, stratified by pre-discharge mean gradients: Group 1 (> 20 mmHg, n = 66) and Group 2 (≤ 20 mmHg, n = 75). We analyzed short-term clinical outcomes and systemic mechanical stress markers (neutrophil-to-lymphocyte ratio [NLR] and lactate dehydrogenase [LDH] levels).

The operative characteristics were similar between the groups. Group 1 exhibited elevated median NLR (3.8 vs. 2.1, p < 0.001) and LDH (304.0 vs. 115.5 U/L, p < 0.001) levels. Despite this biochemical activation, the short-term mortality and reoperation rates were comparable between the two groups. Although Group 1 experienced more frequent non-valvular readmissions (13.6% vs. 2.6%, p = 0.024), their mean gradients demonstrated significant spontaneous regression by 6 months (23.5 to 19.8 mmHg, p < 0.01).

Early "grey zone" gradients are associated with a distinct mechanical stress profile characterized by elevated NLR and LDH levels but do not appear to compromise short-term valvular stability. The spontaneous gradient regression and absence of excess mortality support a safe "watchful waiting" approach, thus avoiding premature reinterventions while maintaining close clinical surveillance.

This study was not registered as a clinical trial because it was a retrospective observational study.