Transaortic flow rate to predict short and long term outcomes in individuals with asymptomatic aortic stenosis

Background

Echocardiographic derived transaortic flow rate (TFR), defined as stroke volume over left ventricular ejection time, has been shown to be associated with increased mortality in asymptomatic mild to severe aortic stenosis (AS) and superior to stroke volume index (SVi) in individuals with symptomatic discordant AS undergoing aortic valve replacement. However, TFR has not been explored alongside SVi in asymptomatic moderate to severe AS, who are a group of interest in risk stratifying for early intervention. Moreover, there is no data where TFR is indexed to body surface area (TFRi).

Purpose

We explored the prognostic value of TFR, TFRi and SVi in a homogenous cohort of asymptomatic patients with moderate to severe AS.

Methods

Subjects with asymptomatic moderate to severe AS were prospectively recruited to the Prognostic Importance of Microvascular Dysfunction in asymptomatic patients with AS (PRIMID) study, a multi-centre observational study in the UK conducted between April 2012 and November 2014. All subjects underwent extensive phenotyping with transthoracic echocardiography, bicycle exercise testing and cardiovascular magnetic resonance (CMR) imaging, with blinded core-lab analysis. Patients were followed up in person for a minimum of 12 months, and through health records thereafter. The composite outcome of interest was: cardiovascular mortality, AVR for symptoms and major adverse cardiovascular events (hospitalisation with heart failure, myocardial infarction, syncope and arrhythmia) at one-year and at five years. A cox proportional hazards model was used to calculate a hazard ratio (HR) and 95% confidence intervals (95% CI). Known co-variables associated with the composite outcome were added into the multivariable model.

Results

Overall, 173 individuals were included with a mean age of 66.3—-±13.3 years and 76.4% were male. Most individuals had severe AS (71.1%, n=123). There were 47 (64.4%) primary outcome events at one-year and 110 (63.6%) events at five-years. Age, sex, N-terminal pro brain natriuretic peptide (NT-pro-BNP), peak aortic velocity (AV Vmax), a positive exercise tolerance test (ETT), myocardial perfusion reserve and right ventricular ejection fraction measured on cardiac magnetic resonance were included in the multivariable model in addition to TFR or TFRi or SVi. Decreasing TFR and TFRi remained independently associated with one-year and five-year composite outcome (Figure 1). However, SVi was only associated with the composite outcome at five-years. AV Vmax (HR: 4.36, 95% CI: 2.59, 7.34, p<0.01) and a positive ETT (HR: 1.87, 95% CI: 1.03, 3.37, p=0.04) were independently associated with the primary outcome at one-year.

Conclusion

Both TFR and TFRi have a potential role in risk stratifying asymptomatic patients with AS and identifying those for earlier intervention, and may be superior to SVi. However, further prospectively designed studies are needed before this becomes part of the routine clinical practice.

Funding Acknowledgement

Type of funding sources: Public grant(s) – National budget only. Main funding source(s): Independent research from a Post-Doctoral Fellowship supported by the National Institute for Health Research (NIHR-PDF 2011-04-51 Geral P McCann).

Short-term adverse remodeling progression in asymptomatic aortic stenosis

OBJECTIVES

Aortic stenosis (AS) is characterised by a long and variable asymptomatic course. Our objective was to use cardiovascular magnetic resonance imaging (MRI) to assess progression of adverse remodeling in asymptomatic AS.

METHODS

Participants from the PRIMID-AS study, a prospective, multi-centre observational study of asymptomatic patients with moderate to severe AS, who remained asymptomatic at 12 months, were invited to undergo a repeat cardiac MRI.

RESULTS

Forty-three participants with moderate-severe AS (mean age 64.4 ± 14.8 years, 83.4% male, aortic valve area index 0.54 ± 0.15 cm2/m2) were included. There was small but significant increase in indexed left ventricular (LV) (90.7 ± 22.0 to 94.5 ± 23.1 ml/m2, p = 0.007) and left atrial volumes (52.9 ± 11.3 to 58.6 ± 13.6 ml/m2, p < 0.001), with a decrease in systolic (LV ejection fraction 57.9 ± 4.6 to 55.6 ± 4.1%, p = 0.001) and diastolic (longitudinal diastolic strain rate 1.06 ± 0.2 to 0.99 ± 0.2 1/s, p = 0.026) function, but no overall change in LV mass or mass/volume. Late gadolinium enhancement increased (2.02 to 4.26 g, p < 0.001) but markers of diffuse interstitial fibrosis did not change significantly (extracellular volume index 12.9 [11.4, 17.0] ml/m2 to 13.3 [11.1, 15.1] ml/m2, p = 0.689). There was also a significant increase in the levels of NT-proBNP (43.6 [13.45, 137.08] pg/ml to 53.4 [19.14, 202.20] pg/ml, p = 0.001).

CONCLUSIONS

There is progression in cardiac remodeling with increasing scar burden even in asymptomatic AS. Given the lack of reversibility of LGE post-AVR and its association with long-term mortality post-AVR, this suggests the potential need for earlier intervention, before the accumulation of LGE, to improve the long-term outcomes in AS.

KEY POINTS

• Current guidelines recommend waiting until symptom onset before valve replacement in severe AS. • MRI showed clear progression in cardiac remodeling over 12 months in asymptomatic patients with AS, with near doubling in LGE. • This highlights the need for potentially earlier intervention or better risk stratification in AS.

Symptom Onset in Aortic Stenosis: Relation to Sex Differences in Left Ventricular Remodeling

OBJECTIVES

The aim of this study was to establish sex differences in remodeling and outcome in aortic stenosis (AS) and their associations with biomarkers of myocardial fibrosis.

BACKGROUND

The remodeling response and timing of symptoms is highly variable in AS, and sex plays an important role.

METHODS

A total of 174 patients (133 men, mean age 66.2 ± 13.3 years) with asymptomatic moderate to severe AS underwent comprehensive stress cardiac magnetic resonance imaging, transthoracic echocardiography, and biomarker analysis (matrix metalloproteinase [MMP]-2, -3, -7, -8, and -9; tissue inhibitor matrix metalloproteinases-1 and -4; syndecan-1 and -4; and N-terminal pro-B-type natriuretic peptide), and were followed up at 6-month intervals. A primary endpoint was a composite of typical AS symptoms necessitating referral for aortic valve replacement, cardiovascular death, or major adverse cardiovascular events.

RESULTS

For a similar severity of AS, male patients demonstrated higher indexed left ventricular (LV) volumes and mass, more concentric remodeling (higher LV mass/volume), a trend to more late gadolinium enhancement (present in 51.1% men vs. 34.1% women; p = 0.057), and higher extracellular volume index than female patients (13.27 [interquartile range (IQR): 11.5 to 17.0] vs. 11.53 [IQR: 10.5 to 13.5] ml/m², p = 0.017), with worse systolic and diastolic function and higher MMP-3 and syndecan-4 levels, whereas female patients had higher septal E/e'. Male sex was independently associated with indexed LV mass (β = 13.32 [IQR: 9.59 to 17.05]; p < 0.001). During median follow-up of 374 (IQR: 351 to 498) days, a primary outcome, driven by spontaneous symptom onset, occurred in 21.8% of male and 43.9% of female patients (relative risk: 0.50 [95% confidence interval: 0.31 to 0.80]; p = 0.004). Measures of AS severity were associated with the primary outcome in both sexes, whereas N-terminal pro-B-type natriuretic peptide, MMP-3, and mass/volume were only associated in men.

CONCLUSIONS

In AS, women tolerate pressure overload with less concentric remodeling and myocardial fibrosis but are more likely to develop symptoms. This may be related to higher wall stress and filling pressures in women.

Stress cardiovascular MR in routine clinical practice: referral patterns, accuracy, tolerance, safety and incidental findings

OBJECTIVE

The use of stress cardiovascular MR (CMR) to evaluate myocardial ischaemia has increased significantly over recent years. We aimed to assess the indications, incidental findings, tolerance, safety and accuracy of stress CMR in routine clinical practice.

METHODS

We retrospectively examined all stress CMR studies performed at our tertiary referral centre over a 20-month period. Patients were scanned at 1.5 T, using a standardised protocol with routine imaging for late gadolinium enhancement. Angiograms of patients were assessed by an interventional cardiologist blinded to the CMR data.

RESULTS

654 patients were scanned (mean age 65±29 years; 63 inpatients; 9.6%). 14% of patients had incidental extracardiac findings, the commonest being liver or renal cysts (6%) and pulmonary nodules (4%). 639 patients (97.7%) received intravenous adenosine, 10 received intravenous dobutamine and 5 patients had both. Of the 15 patients who received dobutamine, 12 had no side-effects/complications, 2 experienced nausea and 1 chest tightness. Of the 644 patients who received adenosine, 43% experienced minor symptoms, 1% had transient heart block and 0.2% had severe bronchospasm requiring termination of infusion. There were no cases of hospitalisation or myocardial infarction. 241 patients also had coronary angiography. For detecting at least moderate stenosis of ≥50%, sensitivity was 86%, specificity 98% and accuracy 89%. For detecting severe stenoses of ≥70%, sensitivity was 91%, specificity 86% and overall accuracy 90%. These results compare very favourably with previous smaller research studies and meta-analyses.

CONCLUSION

We conclude that stress CMR, with adenosine as the main stress agent, is well tolerated, safe and accurate in routine clinical practice.

Unusual extracardiac manifestations of isolated native tricuspid valve endocarditis

Isolated native tricuspid valve endocarditis (TVE) in non-intravenous drug users is a very rare condition. We describe an unusual presentation of Enterococcus faecalis TVE associated with spondylodiscitis, positive cytoplasmic antineutrophil cytoplasmic antibodies and antiproteinase-3 antibodies vasculitic rash in an otherwise healthy patient with no history of intravenous drug use or underlying cardiac abnormalities. A high index of clinical suspicion is required in patients presenting with unusual features and pyrexia of unknown origin. Simple tests including serial blood cultures and echocardiography may help to establish the correct diagnosis and commence appropriate treatment.