Usefulness of the electrocardiogram in predicting cardiovascular mortality in asymptomatic adults with aortic stenosis (from the Simvastatin and Ezetimibe in Aortic Stenosis Study)

Electrocardiographic Markers of Adverse Left Ventricular Remodeling and Myocardial Fibrosis in Severe Aortic Stenosis

The optimal timing for aortic valve replacement (AVR) in aortic stenosis (AS) is still controversial and may be guided by markers of adverse left ventricular (LV) remodeling. We aim to assess electrocardiographic (ECG) strain in relation to LV remodeling and myocardial fibrosis. 83 severe AS patients underwent surgical AVR, with preoperative 12-lead ECG, cardiovascular magnetic resonance with T1 mapping and echocardiography with global longitudinal strain analysis. Collagen volume fraction (CVF) was measured in myocardial biopsies sampled during AVR. Patients with ECG strain had more severe AS, more advanced LV remodeling and evidence of heart failure. Patients with ECG strain had more diffuse fibrosis, as evident by higher mean native T1 values (974.8 ± 34 ms vs. 946.5 ± 28 ms, p < 0.001). ECG strain was the only predictor of increased LV mass index on multivariate regression analysis (OR = 7.10, 95% CI 1.46-34.48, p = 0.02). Patients with persistent ECG strain at 1 year following AVR had more advanced LV remodeling and more histological fibrosis (CVF 12.5% vs. 7.3%, p = 0.009) at baseline assessment. Therefore, ECG strain is a marker of adverse LV remodeling and interstitial myocardial fibrosis. Lack of improvement in ECG strain following AVR indicates more advanced baseline LV injury and higher levels of myocardial fibrosis.

The electrocardiogram: Still a useful marker for LV fibrosis in aortic stenosis

Left ventricular (LV) strain on the electrocardiogram (ECG) (down-sloping, convex ST-segment depression with asymmetric T-wave inversion in leads V5 and V6) reflects fibrosis as a result of subendocardial ischemia. It is associated with a significantly increased risk of cardiovascular events independent of the presence of LV hypertrophy on the echocardiogram or cardiac magnetic resonance (CMR) scan. Ongoing studies of early aortic valve replacement in asymptomatic patients with severe aortic stenosis are using ECG changes as a marker of possible fibrosis shown by midwall late gadolinium enhancement on CMR. However, until these studies report, it is still reasonable to respond to LV strain on the ECG by tightening control of systemic hypertension and consider intervention in cases where indications are otherwise in borderline.

Sudden cardiac death in asymptomatic patients with aortic stenosis

OBJECTIVE

We retrospectively analysed outcome data from the Simvastatin and Ezetimibe in Aortic Stenosis (SEAS) study to assess the incidence and potential risk factors of sudden cardiac death (SCD) in this prospectively followed cohort of asymptomatic patients with aortic stenosis (AS).

METHODS

Of the 1873 patients included in SEAS, 1849 (99%) with mild to moderate AS (jet velocity 2.5-4.0 m/s at baseline) and available clinical, echocardiographic and follow-up data were analysed. Patients undergoing aortic valve replacement were censored at the time of operation.

RESULTS

During an overall follow-up of 46.1±14.6 months, SCD occurred in 27 asymptomatic patients (1.5%) after a mean of 28.3±16.6 months. The annualised event rate was 0.39%/year. The last follow-up echocardiography prior to the event showed mild to moderate stenosis in 22 and severe stenosis (jet velocity >4 m/s) in 5 victims of SCD. The annualised event rate after the diagnosis of severe stenosis was 0.60%/year compared with 0.46%/year in patients who did not progress to severe stenosis (p=0.79). Patients with SCD were older (p=0.01), had a higher left ventricular mass index (LVMI, p=0.001) and had a lower body mass index (BMI, p=0.02) compared with patients surviving follow-up. Cox regression analysis identified age (HR 1.06, 95% CI 1.01 to 1.11 per year, p=0.02), increased LVMI (HR 1.20, 95% CI 1.10 to 1.32 per 10 g/m², p<0.001) and lower BMI (HR 0.87, 95% CI 0.79 to 0.97 per kg/m², p=0.01) as independent risk factors of SCD.

CONCLUSION

SCD in patients with asymptomatic mild to moderate AS is rare and strongly related to left ventricular hypertrophy but not stenosis severity.

Absence of electrocardiographic left ventricular hypertrophy is associated with increased mortality after transcatheter aortic valve replacement

BACKGROUND

Electrocardiographic (ECG) left ventricular hypertrophy (LVH) has been associated with increased mortality in patients with asymptomatic aortic stenosis (AS) and hypertension. However, patients with symptomatic AS undergoing transcatheter aortic valve replacement (TAVR) have higher percentages of myocardial fibrosis or amyloidosis that have been associated with decreased ECG voltage and worse outcomes.

HYPOTHESIS

We tested the hypothesis that baseline ECG LVH is independently associated with increased all-cause mortality after TAVR.

METHODS

A total of 231 patients (96 men; mean age 84.7 ± 7.8 years) that underwent TAVR at our institution were included. Cornell voltage, defined as S_V3 + R_aVL, was used to assess for presence of ECG LVH using gender-specific cut-off values. We used the Kaplan-Meier estimator to derive survival curves. Multivariate Cox regression analysis was used to compare mortality between patients without vs with ECG LVH and adjust for echocardiographic LVH and predictors of mortality in this cohort.

RESULTS

Over a follow-up time of 16.3 ± 10.4 months, the absence of ECG LVH was significantly associated with increased mortality (40.4% vs 23.6% at 2-years, log rank P = 0.003). After adjusting for echocardiographic LVH and predictors of mortality in our cohort, the absence of ECG LVH remained a predictor of increased mortality (HR = 1.79, CI 95% 1.02-3.14, P = 0.042).

CONCLUSIONS

The absence of ECG LVH was independently associated with increased mortality in patients undergoing TAVR. Baseline ECG may have an important prognostic role in these patients and could lead to further testing to evaluate for myocardial fibrosis or amyloidosis.

Electrocardiographic Predictors of Cardiovascular Mortality

Cardiovascular diseases are the main causes of mortality. Sudden cardiac death may also appear in athletes, due to underlying congenital or inherited cardiac abnormalities. The electrocardiogram is used in clinical practice and clinical trials, as a valid, reliable, accessible, inexpensive method. The aim of the present paper was to review electrocardiographic (ECG) signs associated with cardiovascular mortality and the mechanisms underlying those associations, providing a brief description of the main studies in this area, and consider their implication for clinical practice in the general population and athletes. The main ECG parameters associated with cardiovascular mortality in the present paper are the P wave (duration, interatrial block, and deep terminal negativity of the P wave in V1), prolonged QT and Tpeak-Tend intervals, QRS duration and fragmentation, bundle branch block, ST segment depression and elevation, T waves (inverted, T wave axes), spatial angles between QRS and T vectors, premature ventricular contractions, and ECG hypertrophy criteria.