Aortic stenosis. Clinical evaluation and optimal timing of surgery

Natural progression of low-gradient severe aortic stenosis with preserved ejection fraction

Because the natural progression of low-gradient aortic stenosis (LGAS) has not been well defined, we performed a retrospective study of 116 consecutive patients with aortic stenosis who had undergone follow-up echocardiography at a median interval of 698 days (range, 371-1,020 d). All patients had preserved left ventricular ejection fraction (>0.50) during and after follow-up. At baseline, patients were classified by aortic valve area (AVA) as having mild stenosis (≥1.5 cm(2)), moderate stenosis (≥1 to <1.5 cm(2)), or severe stenosis (<1 cm(2)). Severe aortic stenosis was further classified by mean gradient (LGAS, mean <40 mmHg; high-gradient aortic stenosis [HGAS], mean ≥40 mmHg). We compared baseline and follow-up values among 4 groups: patients with mild stenosis, moderate stenosis, LGAS, and HGAS. At baseline, 30 patients had mild stenosis, 54 had moderate stenosis, 24 had LGAS, and 8 had HGAS. Compared with the moderate group, the LGAS group had lower AVA but similar mean gradient. Yet the actuarial curves for progressing to HGAS were significantly different: 25% of patients in LGAS reached HGAS status significantly earlier than did 25% of patients in the moderate-AS group (713 vs 881 d; P=0.035). Because LGAS has a high propensity to progress to HGAS, we propose that low-gradient aortic stenosis patients be closely monitored as a distinct subgroup that warrants more frequent echocardiographic follow-up.

Left atrial size and function as predictors of new-onset of atrial fibrillation in patients with asymptomatic aortic stenosis: the simvastatin and ezetimibe in aortic stenosis study

BACKGROUND

Left atrial (LA) size and function change with chronically increased left ventricular (LV) filling pressures. It remains unclear whether these variations in LA parameters can predict new-onset atrial fibrillation (AF) in asymptomatic patients with aortic stenosis (AS).

METHODS

Data were obtained in asymptomatic patients with mild-to-moderate AS (2.5 ≤ transaortic Doppler velocity ≤ 4.0m/s), preserved LV ejection fraction (EF), no previous AF, and were enrolled in the Simvastatin and Ezetimibe in Aortic Stenosis study. Peak-aortic velocity, LA(max) volume & LAmin volume were measured by echocardiography. LA conduit (LA(con)) volume was defined as LV stroke volume-LA stroke volume. LA function was expressed as LA-EF (LA(max)-LAmin volume/LA(max)).

RESULTS

In the 1159 patients included, new-onset AF occurred in 71 patients (6.1%) within a mean follow-up of 4.2 ± 0.9 years. Mean age was 66 ± 9.7 years, aortic valve area index 0.6 ± 0.2 cm(2)/m(2), LV mass 99.2 ± 29.7 g/m(2), LA(max) volume 34.6 ± 12.0 mL/m(2), LAmin volume 17.9 ± 9.3 mL/m(2), LA-EF 50 ± 15% and LA(con) volume 45 ± 21 mL/m(2). Baseline LAmin volume predicted new-onset AF in Cox multivariable analysis (HR:2.3 [95%CI:1.3-4.4], P<0.01), and added prognostic information on AF development beyond conventional risk factors (likelihood ratio, P<0.01). In comparison of c-indexes LAmin volume was superior to all other LA measurements. Net reclassification index improved by 15.9% when adding LAmin volume to a model with classic risk factors for AF (P=0.01).

CONCLUSION

LAmin volume independently predicted new-onset AF in patients with asymptomatic AS and was superior to LA-EF, LA(con) and LA(max) volumes and conventional risk factors.

Aortic valve sclerosis: is it a cardiovascular risk factor or a cardiac disease marker?

BACKGROUND

Aortic valve sclerosis, without stenosis, has been associated with an increased cardiovascular mortality and morbidity due to myocardial infarction. However, it is unclear whether it is a cardiovascular risk factor or a cardiac disease marker. The goal of our study is to evaluate the difference in the prevalence of cardiovascular disease and risk factors among patients with or without aortic sclerosis.

METHODS

This observational study compared a group of 142 consecutive subjects with aortic valve sclerosis, assigned as group S, with a group of 101 subjects without aortic sclerosis, assigned as group C. Patients with bicuspid aortic valves and those with antegrade Doppler velocity across aortic valve leaflets exceeding 2.0 m/sec were excluded.

RESULTS

Mean ages of groups S and C were 71 +/- 8, and 68.8 +/- 6 years, respectively (P value = not significant). The prevalence of smoking, diabetes, hypercholesterolemia, hypertension, pulse pressure, left ventricular diastolic dysfunction, atrial fibrillation, and stroke was not significantly different between the two groups. However, there was a significantly higher prevalence of left ventricular hypertrophy (P = 0.05), ventricular arrhythmias (P = 0.02), myocardial infarction (P = 0.04), and systolic heart failure (P = 0.04) in aortic sclerosis group.

CONCLUSIONS

Aortic sclerosis is associated with a higher prevalence of left ventricular hypertrophy, ventricular arrhythmias, myocardial infarction, and systolic heart failure, while the prevalence of cardiovascular risk factors is not different between aortic sclerosis patients and controls. Hence, aortic sclerosis represents a cardiac disease marker useful for early identification of high-risk patients beyond cardiovascular risk factors rate.

Are angiotensin converting enzyme inhibitors beneficial in patients with aortic stenosis?

Angiotensin converting enzyme (ACE) inhibitors may become an accepted form of treatment for aortic stenosis in the future.

When is concomitant aortic valve replacement indicated in patients with mild to moderate stenosis undergoing coronary revascularization?

Mild to moderate aortic stenosis is a common finding in patients presenting for coronary artery bypass grafting (CABG), and its management is controversial. However, review of available data suggests a surgical strategy for these patients. Recent data demonstrate that 1) progression of aortic stenosis is more rapid in those with leaflet calcification; 2) the addition of aortic valve replacement to CABG in patients with mild to moderate stenosis does not increase hospital mortality when compared with bypass surgery alone; 3) hospital mortality for aortic valve replacement after previous bypass surgery has declined in recent years; 4) aortic valve replacement places the patient at risk for prosthesis-related complications; 5) the limited 10-year survival (competing risk of death) leaves only a minority of individuals with mild aortic stenosis alive and eligible for aortic valve replacement 10 years after bypass surgery; and 6) combined aortic valve replacement and CABG confers a survival benefit in those with moderate aortic stenosis but not in those with mild aortic stenosis. Therefore, in the coronary artery bypass patient with moderate aortic stenosis, leaflet calcification, and life expectancy greater than 5 years, concomitant aortic valve replacement is advised. In contrast, aortic valve replacement is rarely indicated in those with mild aortic stenosis.

Increased plasma natriuretic peptide levels reflect symptom onset in aortic stenosis

BACKGROUND

The onset of symptoms is a critical point in the natural history of aortic stenosis and the cardinal indication for valve replacement. This study assessed the associations between natriuretic peptide levels, disease severity, and cardiac symptoms in aortic stenosis.

METHODS AND RESULTS

Seventy-four patients with isolated aortic stenosis underwent independent assessment of symptoms, transthoracic echocardiography, and measurement of plasma levels of atrial natriuretic peptide, brain natriuretic peptide (BNP), and N-BNP. Natriuretic peptide levels were also measured in 100 clinically normal control subjects. The aortic valve area was smaller in symptomatic patients (n=45) than in asymptomatic patients (n=29; mean, 0.71+/-0.23 cm2 and 0.99+/-0.31 cm2, respectively; P<0.0001). Plasma natriuretic peptide levels were higher in symptomatic patients than in asymptomatic patients (for N-BNP: median, 112 versus 33 pmol/L; interquartile range, 70 to 193 versus 16 to 58 pmol/L, respectively; P=0.0002). After adjustment for age, sex, serum creatinine, aortic valve area, and left ventricular ejection fraction, N-BNP levels were 1.74 times higher (95% confidence interval, 1.12 to 2.69) for symptomatic than asymptomatic patients with aortic stenosis (P=0.014). Natriuretic peptide levels increased with the New York Heart Association class (for N-BNP median values were 13, 34, 105, and 202 pmol/L for normal control subjects, class I, class II, and class III/IV patients, respectively; interquartile ranges for the same patients were 8 to 21, 16 to 58, 57 to 159, and 87 to 394 pmol/L; P<0.0001). Similar associations were observed for BNP and atrial natriuretic peptide.

CONCLUSIONS

Plasma natriuretic peptide levels are elevated in symptomatic patients with aortic stenosis. Measurement of natriuretic peptides may complement clinical and echocardiographic evaluation of patients with aortic stenosis.

Clinical significance of iodine-123-15-(p-iodophenyl)-3-R, S-methylpentadecanoic acid myocardial scintigraphy in patients with aortic valve disease

The present study sought to determine whether myocardial fatty acid metabolism as assessed with iodine-123-labeled 15-(p-iodophenyl)-3-R,S-methylpentadecanoic acid (BMIPP) scintigraphy is impaired in patients with aortic valve disease (AVD) and whether the degree of the metabolic abnormality reflects the severity of AVD. BMIPP scintigraphy was performed in 12 patients with aortic stenosis (AS), 14 patients with aortic regurgitation (AR), and 9 healthy volunteers, and from that the heart-mediastinum uptake ratio (H/M ratio) corrected by the left ventricular (LV) mass (U/Mass ratio) and the myocardial washout rate (WR) were obtained. The H/M ratio tended to be higher in patients than in healthy volunteers (3.3 +/- 0.7 for AS, 3.5 +/- 0.5 for AR, 3.0 +/- 0.3 for healthy volunteers), and the WR was significantly higher in patients than in healthy volunteers (42.8 +/- 9.1% for AS, 35.7 +/- 6.5% for AR, 19.6 +/- 9.1% for healthy volunteers, p<0.01). In the AS patients, the U/Mass ratio showed significant negative correlations (r=-0.79 to -0.90, all p<0.01) and the WR showed significant positive correlations (r=0.61 to 0.82, all p<0.01) with transaortic pressure gradient, LV wall thickness, and LV mass. Similarly, in AR patients these BMIPP parameters showed proportional changes to the LV volumes and LV mass (r=-0.79 to -0.83, all p<0.01 for U/Mass ratio, r=0.55 to 0.70, p<0.05 to <0.01 for WR). In the 9 patients who underwent aortic valve replacement, the BMIPP parameters tended to normalize with increasing U/Mass ratio (0.90 +/- 0.41 x 10(-2)/g to 1.34 +/- 0.59 x 10(-2)/g, p<0.05) and decreasing WR (41.9 +/- 8.8% to 35.4 +/- 9.2%, p<0.01) after surgery. Myocardial fatty acid metabolism as assessed with BMIPP scintigraphy was impaired in patients with aortic valve disease and the U/Mass ratio and WR reflect the severity. These parameters may be useful for the noninvasive assessment of the myocardial metabolic abnormalities caused by hemodynamic overload.

Treatment decision in asymptomatic aortic valve stenosis: role of exercise testing

OBJECTIVE

To determine the prognostic value of exercise testing, valve area, and maximum transaortic pressure gradient in asymptomatic patients with aortic valve stenosis.

SETTING

The outpatient service of a tertiary referral centre for cardiology.

DESIGN

Prospective clinical study.

PATIENTS

66 consecutive patients with isolated severe aortic stenosis (aortic valve area </= 1.0 cm(2)) were selected over a 58 month period. Mean (SD) follow up was 14.77 (11.93) months.

INTERVENTIONS

At the initial visit Doppler echocardiography and exercise testing were performed to evaluate ST segment depression and the development of symptoms of aortic stenosis, ventricular arrhythmia, or inadequate rise of systolic blood pressure during exercise. Follow up clinical examinations were performed every three months thereafter to record the onset of symptoms.

MAIN OUTCOME MEASURES

Sudden death or the development of symptoms.

RESULTS

Eight patients developed dizziness during exercise testing but made a rapid and spontaneous recovery. No other complications of exercise testing occurred. Survival curves, with or without the occurrence of end point events for the variables studied, showed significant differences for positive versus negative exercise testing (p = 0.0001) and aortic valve area < 0.7 cm(2) v >/= 0.7 cm(2) (p = 0.0021). There was no relation between the end points and transaortic gradient (p = 0.6882). In multivariate analysis, a hazard ratio of 7.43 was calculated for patients with a positive versus a negative exercise stress test. Although asymptomatic in daily life, 6% of the patients (4/66) experienced sudden death; all these had a positive exercise test and an aortic valve area of </= 0.6 cm(2).

CONCLUSIONS

Exercise testing is safe and is of prognostic value in asymptomatic patients with aortic stenosis.