Markers of left ventricular decompensation in aortic stenosis

Abstract

Calcified aortic stenosis is a condition that affects the valve and the myocardium. As the valve narrows, left ventricular hypertrophy occurs initially as an adaptive mechanism to maintain cardiac output. Ultimately, the ventricle decompensates and patients transition towards heart failure and adverse events. Current guidelines recommend aortic valve replacement in patients with severe aortic stenosis and evidence of decompensation based on either symptoms or an impaired ejection fraction <50%. However, symptoms can be subjective and correlate only modestly with the severity of aortic stenosis whilst impaired ejection fraction is an advanced manifestation and often irreversible. In this review, the authors will discuss the pathophysiology of left ventricular hypertrophy and the transition to heart failure. Subsequently, the authors will examine novel biomarkers that may better identify the transition from hypertrophy to heart failure and therefore guide the optimal timing for aortic valve replacement.

Keywords::

• aortic stenosis
• cardiac MRI
• echocardiography
• left ventricular decompensation
• left ventricular hypertrophy
• myocardial fibrosis
• myocardial T1 mapping
• myocyte death
• tissue Doppler imaging

Financial & competing interests disclosure

CWL Chin is supported by the NRF-MOH Healthcare Research Scholarship (PhD) from the National Research Foundation-Ministry of Health, Singapore. V Vassiliou and SK Prasad are supported by the NIHR Cardiovascular Disease and Biomedical Research Unit at the Royal Brompton and Harefield NHS Foundation Trust and Imperial College London and the Rosetrees Trust. M Dweck, WSA Jenkins and DE Newby are supported by the British Heart Foundation (BHF). The authors have no other relevant affiliations or financial involvement with any organization or entity with a financial interest in or financial conflict with the subject matter or materials discussed in the manuscript apart from those disclosed.

No writing assistance was utilized in the production of this manuscript.

Key issues

• Aortic stenosis is a disease of the valve and the myocardium. In the myocardium, the transition from hypertrophy to heart failure is a key determinant of the development of symptoms and adverse events. This decompensation is mediated by progressive myocyte death and myocardial fibrosis.

• Currently, aortic valve replacement is recommended in patients with severe aortic stenosis and evidence of decompensation, based on either symptoms or impaired ejection fraction <50%.

• Recent studies suggest that early aortic valve replacement improves clinical outcomes in asymptomatic patients with severe disease and preserved systolic function.

• There is emerging interest in novel markers of left ventricular (LV) decompensation to identify patients who may benefit from early aortic valve replacement. These biomarkers include the following:

  • – Advanced LV hypertrophy. This can be assessed with different degrees of sensitivity using the electrocardiogram, echocardiography and cardiovascular magnetic resonance imaging and is associated with a worse prognosis.

  • – Speckle tracking echocardiography. This is more sensitive than the systolic ejection fraction in detecting intrinsic myocardial dysfunction. Impaired longitudinal strain and strain rate predict an adverse outcome in asymptomatic patients with aortic stenosis.

  • – Diastolic dysfunction. This precedes an impaired ejection fraction and is associated with the onset and progression of symptoms. However, there is some inconsistency in the literature with respect to its prognostic role.

  • – Brain natriuretic peptide and N-terminal pro-brain natriuretic peptide concentrations. These appear useful in evaluating patients with equivocal symptoms. However, their prognostic value in asymptomatic patients is conflicting.

  • – High-sensitivity cardiac troponin concentrations hold potential in detecting the myocyte death that drives the transition from hypertrophy to heart failure. More studies are needed to confirm their prognostic value.

  • – Myocardial fibrosis assessment using cardiovascular magnetic resonance. This technique can now be used to identify and quantify the fibrosis driving LV decompensation with initial data suggesting this approach can provide important prognostic data.

• Future research is needed to investigate these novel biomarkers and assess whether they can better identify asymptomatic patients who would benefit from early aortic valve replacement.

Notes