Development of paradoxical low-flow, low-gradient severe aortic stenosis

Area of Science:

• Cardiology
• Echocardiography
• Valvular Heart Disease

Background:

• Severe aortic stenosis (sAS) with preserved left ventricular ejection fraction (LVEF) can present as low-flow, low-gradient sAS (LFLG-sAS).
• LFLG-sAS is associated with poor prognosis and has been hypothesized to represent an end-stage of sAS.
• Longitudinal data characterizing the progression to LFLG-sAS are limited.

Purpose of the Study:

• To investigate whether LFLG-sAS develops from normal-flow, high-gradient sAS (NFHG-sAS) or represents a distinct pathophysiological entity.
• To analyze the longitudinal changes in cardiac structure and function preceding LFLG-sAS.

Main Methods:

• Retrospective analysis of transthoracic echocardiogram (TTE) data from patients with sAS and preserved LVEF (≥50%).
• Identification of LFLG-sAS (stroke volume index <35 mL/m², mean gradient <40 mmHg) and age/sex/date-matched NFHG-sAS and normal-flow, low-gradient sAS (NFLG-sAS) cohorts.
• Comparison of serial TTE findings, including left ventricular (LV) mass index, relative wall thickness, LV end-diastolic diameter, deceleration time, and LVEF, over a five-year period prior to the index TTE.

Main Results:

• Only 5% of LFLG-sAS patients had a preceding high-gradient stage.
• LFLG-sAS patients showed increasing relative wall thickness without LV mass index change, unlike NFHG-sAS patients who had marked LV mass index increase.
• LFLG-sAS was associated with the greatest reduction in LV end-diastolic diameter, deceleration time, and LVEF compared to NFLG-sAS and NFHG-sAS.

Conclusions:

• LFLG-sAS represents a distinct presentation of severe aortic stenosis.
• This distinct presentation is characterized by a unique cardiac remodeling pathway.
• LFLG-sAS is uncommonly preceded by a high-gradient stage, challenging the notion of it being a simple end-stage progression of NFHG-sAS.