Left Ventricular Longitudinal Strain in Characterization and Outcome Assessment of Mixed Aortic Valve Disease Phenotypes

OBJECTIVES

The aims of this study were to characterize the interplay between mixed aortic valve disease (MAVD) phenotypes (defined by concomitant severities of aortic stenosis and aortic regurgitation) and left ventricular global longitudinal strain (LV-GLS), and to assess the prognostic utility of LV-GLS in MAVD.

BACKGROUND

Little is known about the way LV-GLS separates MAVD phenotypes and if it is associated with their outcomes.

METHODS

This observational cohort study evaluated 783 consecutive adult patients with left ventricular ejection fraction ≥50% and MAVD, which was defined as coexisting with at least moderate aortic stenosis and at least moderate aortic regurgitation. We measured the conventional echocardiographic variables and average LV-GLS from apical long, 2- and 4-chamber views. The primary endpoint was all-cause mortality.

RESULTS

Mean age of patients was 69 ± 15 years, and 58% were male. Mean LV-GLS was -14.7 ± 2.9%. In total, 458 patients (59%) underwent aortic valve replacement at a median period of 50 days (25th to 75th percentile range: 6 to 560 days). During a median follow-up period of 5.6 years (25th to 75th percentile range: 1.8 to 9.4 years), 391 patients (50%) died. When stratified patients into tertiles according to LV-GLS values, patients with worse LV-GLS had worse outcomes (p < 0.001). LV-GLS was independently associated with mortality (hazard ratio: 1.09; 95% confidential intervals: 1.04 to 1.14; p < 0.001), with the relationship between LV-GLS and mortality being linear.

CONCLUSIONS

LV-GLS is associated with all-cause mortality. LV-GLS may be useful for risk stratification in patients with MAVD.

Impact of left atrial strain mechanics on exercise intolerance and need for septal reduction therapy in hypertrophic cardiomyopathy

AIMS

We sought to assess the relationship between left atrial (LA) strain mechanics and exercise intolerance, and to evaluate the prognostic impact of LA strain mechanics on clinical deterioration necessitating septal reduction therapy in hypertrophic cardiomyopathy (HCM).

METHODS AND RESULTS

Consecutive HCM patients who underwent exercise stress echocardiography and cardiopulmonary exercise testing on the same day between October 2015 and April 2019 were enrolled prospectively. LA strain mechanics were analysed using speckle tracking echocardiography. LA stiffness was calculated as the ratio of E/e' ratio to LA reservoir strain. The study cohort was divided into four groups based on the quartile of percent-predicted peak VO2, and exercise intolerance was defined as the lowest quartile (≤51%). Of 532 patients studied (mean age: 51 ± 15 years, 42% female), 138 patients demonstrated exercise intolerance. As exercise capacity worsened, LA strain mechanics worsened along a continuum (P < 0.001). LA contractile strain with a cut-off of -13.9% was optimal at identifying exercise intolerance. On multivariable analysis, worse LA contractile strain was an independent predictor for exercise intolerance (P = 0.002). Of patients with left ventricular outflow tract obstruction, patients with LA stiffness worse than the median value (≥0.41) were significantly more likely to require septal reduction therapy than those with better LA stiffness (P = 0.026).

CONCLUSION

Worse LA contractile strain was an independent predictor for exercise intolerance in HCM. Patients with worse LA stiffness had a higher probability of clinical deterioration necessitating septal reduction therapy.

Determining the thresholds for abnormal left ventricular strains in healthy subjects by echocardiography: a meta-analysis

Background

Left ventricular global longitudinal strain (LVGLS), circumferential strain (LVGCS) and radial strain (LVGRS) are echocardiographic parameters with wide clinical applicability. However, the thresholds for abnormal left ventricular (LV) strains, particularly the lower limits of normal (LLN), are not well established. This meta-analysis determined the mean and LLN of two- (2D) and three-dimensional (3D) LV strain in healthy subjects and factors that influence strain measurements.

Methods

We searched PubMed, Embase and Cochrane databases until 31 December 2019 for studies reporting left ventricular (LV) global strain in at least 50 healthy subjects. We pooled means and LLNs of 2D and 3D LV strain using random-effects models, and performed subgroup and meta-regression analysis for LVGLS.

Results

Forty-four studies were eligible totaling 8,910 subjects. The pooled means and LLNs (95% confidence intervals) were -20.1% (-20.7%, -19.6%) and -15.4% (-16.0%, -14.7%) respectively for 2D-LVGLS; -21.9% (-23.4%, -20.3%) and -15.3% (-16.9%, -13.8%) respectively for 2D-LVGCS; and 48.4% (43.8%, 53.0%) and 25.5% (17.8%, 33.1%) respectively for 2D-LVGRS. All pooled analyses demonstrated significant heterogeneity, and means and LLNs of and 3D-LV strains differed marginally from 2D. Only vendor software was associated with differences in pooled means and LLN of 2D-LVGLS.

Conclusions

In conclusion, pooled means and LLNs of 2D- and 3D-LV global strain parameters in healthy subjects were reported. Based on the pooled LLNs, thresholds for abnormal, borderline and normal strains can be defined, such as less negative than -14.7%, between -14.7% and -16.0% and more negative than -16.0% respectively for 2D-LVGLS, and 2D-LVGLS values are only affected by vendor software.

Abstract 13434: Improved Diagnostic Performance of Contemporary Transesophageal Echocardiography With Three-dimensional Imaging for Infective Endocarditis

Introduction: Infective endocarditis (IE) is associated with high morbidity and mortality. Conventionally, a repeat transesophageal echocardiogram (TEE) is necessary if the first TEE is negative, and there is high clinical suspicion. We aimed to investigate the diagnostic performance of contemporary TEE for IE.

Hypothesis: We hypothesize that with advancements in TEE imaging, including three-dimensional (3D) imaging, the diagnostic performance of TEE for IE would be improved.

Methods: Patients who had two or more TEEs at our center, within 6 months, for evaluation of IE in 2011 (pre-3D imaging) and 2019 (post-3D imaging) were included. Patients not meeting the Duke criteria for IE (n=899) were excluded. The primary endpoint was the sensitivity of TEE to detect IE. TEE sensitivity was also compared among the different subtypes of IE (native valve, prosthetic valve, device-related, central line-related, and aortic prosthetic graft-related).

Results: 242 patients were included: 70 in 2011 and 172 in 2019. In 2011, there were more smokers and a lower rate of pacing devices; otherwise, there were no significant differences in baseline characteristics, including intravenous drug use. The sensitivity of the initial TEE for IE was 85.7% in 2011, improving significantly to 95.3% in 2019 (p=0.01). The improved diagnostic performance in 2019 was mainly driven by the improved detection of prosthetic valve IE (70.8% vs. 93.7%, p=0.009). There were no significant differences for the other subtypes of IE (Figure). In 2019, patients had a higher rate of IE diagnosis within 15 days of index admission, which did not reach statistical significance (n=161, 93.6% vs. n=62, 88.6% in 2011, p=0.19). Kaplan Meier analysis demonstrated that patients in 2019 had a higher rate of procedures for endocarditis (p=0.01).

Conclusions: Contemporary TEE imaging including 3D technology improved the detection of IE on the initial TEE, mainly driven by improved detection of prosthetic valve IE.

Complementary Diagnostic and Prognostic Contributions of Cardiac Computed Tomography for Infective Endocarditis Surgery

BACKGROUND

Cardiac computed tomography (CT) is emerging as an adjunctive modality to echocardiography in the evaluation of infective endocarditis (IE) and surgical planning. CT studies in IE have, however, focused on its diagnostic rather than prognostic utility, the latter of which is important in high-risk diseases like IE. We evaluated the associations between cardiac CT and transesophageal echocardiography (TEE) findings and adverse outcomes after IE surgery.

METHODS

Of 833 consecutive patients with surgically proven IE during May 1, 2014 to May 1, 2019, at Cleveland Clinic, 155 underwent both preoperative ECG-gated contrast-enhanced CT and TEE. Multivariable analyses were performed to identify CT and TEE biomarkers that predict adverse outcomes after IE surgery, adjusting for EuroSCORE II (European System for Cardiac operative Risk Evaluation II).

RESULTS

CT and TEE were positive for IE in 123 (75.0%) and 124 (75.6%) of patients, respectively. Thirty-day mortality occurred in 3 (1.9%) patients and composite mortality or morbidities in 72 (46.5%). Pseudoaneurysm or abscess detected on TEE was the only imaging biomarker to show independent association with composite mortality or morbidities in-hospital, with odds ratio (95% CI) of 3.66 (1.76-7.59), P=0.001. There were 17 late deaths, and both pseudoaneurysm or abscess detected on CT and fistula detected on CT were the only independent predictors of total mortality during follow-up, with hazards ratios (95% CI) of 3.82 (1.25-11.7), P<0.001 and 9.84 (1.89-51.0), P=0.007, respectively.

CONCLUSIONS

We identified cardiac CT and TEE features that predicted separate adverse outcomes after IE surgery. Imaging biomarkers can play important roles incremental to conventional clinical factors for risk stratification in patients undergoing IE surgery.

Contemporary Outcomes in Low-Gradient Aortic Stenosis Patients Who Underwent Dobutamine Stress Echocardiography

Background

Detection of flow reserve (FR) by dobutamine stress echocardiography is used for risk stratification in low‐gradient aortic stenosis (AS). Prognostic significance of dobutamine stress echocardiography in the transcatheter aortic valve replacement era is unclear. We aimed to assess the current relevance of FR.

Methods and Results

We studied 235 patients with low‐gradient severe AS (rest aortic valve area ≤1.0 cm² or indexed aortic valve area ≤0.60 cm²/m²; mean aortic valve gradient <40 mm Hg) and left ventricular ejection fraction <50%) with dobutamine stress echocardiography done September 2010 through July 2016. FR was defined by ≥20% stroke volume increase. We diagnosed “true‐severe AS” if peak aortic valve velocity ≥4 m/s occurred with aortic valve area ≤1.0 cm² (or indexed aortic valve area ≤0.6 cm²/m²). At a median time of 51 days, 128 patients underwent aortic valve replacement,either surgical aortic valve replacement (n=42) or transcatheter aortic valve replacement (n=86). FR was observed in 138 patients, while 86 patients had true‐severe AS. During median follow‐up of 2.3 years, 138 patients died. In a multivariable model, aortic valve replacement (hazard ratio 0.41, 95% CI: 0.29–0.58, P <0.001) and lower Society of Thoracic Surgeons score (hazard ratio 1.06, 95% CI: 1.04–1.09, P<0.001) were associated with better survival, while FR was not predictive. aortic valve replacement was associated with survival regardless of the presence or absence of FR or AS severity stratification.

Conclusions

In low‐gradient AS with reduced ejection fraction, FR or AS severity stratification by dobutamine stress echocardiography was not associated with survival. Aortic valve replacement was associated with better survival in low‐gradient AS independent of FR.

See Editorial by Annabi et al

Machine Learning of 12-Lead QRS Waveforms to Identify Cardiac Resynchronization Therapy Patients With Differential Outcomes

BACKGROUND

Cardiac resynchronization therapy (CRT) improves heart failure outcomes but has significant nonresponse rates, highlighting limitations in ECG selection criteria: QRS duration (QRSd) ≥150 ms and subjective labeling of left bundle branch block (LBBB). We explored unsupervised machine learning of ECG waveforms to identify CRT subgroups that may differentiate outcomes beyond QRSd and LBBB.

METHODS

We retrospectively analyzed 946 CRT patients with conduction delay. Principal component analysis (PCA) dimensionality reduction obtained a 2-dimensional representation of preCRT 12-lead QRS waveforms. k-means clustering of the 2-dimensional PCA representation of 12-lead QRS waveforms identified 2 patient subgroups (QRS PCA groups). Vectorcardiographic QRS area was also calculated. We examined following 2 primary outcomes: (1) composite end point of death, left ventricular assist device, or heart transplant, and (2) degree of echocardiographic left ventricular ejection fraction (LVEF) change after CRT.

RESULTS

Compared with QRS PCA Group 2 (n=425), Group 1 (n=521) had lower risk for reaching the composite end point (HR, 0.44 [95% CI, 0.38-0.53]; P<0.001) and experienced greater mean LVEF improvement (11.1±11.7% versus 4.8±9.7%; P<0.001), even among patients with LBBB with QRSd ≥150 ms (HR, 0.42 [95% CI, 0.30-0.57]; P<0.001; mean LVEF change 12.5±11.8% versus 7.3±8.1%; P=0.001). QRS area also stratified outcomes but had significant differences from QRS PCA groups. A stratification scheme combining QRS area and QRS PCA group identified patients with LBBB with similar outcomes to non-LBBB patients (HR, 1.32 [95% CI, 0.93-1.62]; difference in mean LVEF change: 0.8% [95% CI, -2.1% to 3.7%]). The stratification scheme also identified patients with LBBB with QRSd <150 ms with comparable outcomes to patients with LBBB with QRSd ≥150 ms (HR, 0.93 [95% CI, 0.67-1.29]; difference in mean LVEF change: -0.2% [95% CI, -2.7% to 3.0%]).

CONCLUSIONS

Unsupervised machine learning of ECG waveforms identified CRT subgroups with relevance beyond LBBB and QRSd. This method may assist in objective classification of bundle branch block morphology in CRT.

The role of cardiac imaging in hospitalized COVID-19-positive patients

COVID-19 infection is associated with several cardiac complications with high rates of adverse outcomes. Cardiac imaging has different utility in different clinical scenarios, and the importance of minimizing healthcare worker exposure should be considered. Cardiac imaging should only be ordered if its benefits outweigh its risks, with anticipated changes in acute treatment and outcomes, and no suitable alternative of sufficient adequacy is available. Indications for advanced cardiac imaging for COVID-19 patients in the acute phase are limited, although follow-up imaging in the convalescent stage may provide prognostic importance in recovered COVID-19 patients with positive troponin or decompensated heart failure.

Long-Term Outcomes in Patients With Mixed Aortic Valve Disease and Preserved Left Ventricular Ejection Fraction

Background

Concurrent presence of aortic stenosis and aortic regurgitation is termed mixed aortic valve disease (MAVD). Although multiple articles have addressed patients with “isolated” aortic stenosis or aortic regurgitation, the natural history, impact, and outcomes of MAVD are not well defined. Here, we evaluate long‐term outcomes in patients with MAVD and cardiovascular adaptations to chronic MAVD.

Methods and Results

This observational cohort study evaluated 862 adult patients (56.8% male) with preserved left ventricular ejection fraction and at least moderate aortic regurgitation and moderate aortic stenosis. Primary outcome was all‐cause mortality. Subgroup analysis was based on treatment modality (aortic valve replacement [AVR] versus medical management). A regression analysis of longitudinal echocardiographic parameters was performed to assess the natural history of MAVD. Mean age was 68±15 years, and mean left ventricular ejection fraction was 58±5%. At 4.6 years (25th–75th percentile range, 1.0–8.7), 58.6% of patients underwent an AVR and 48.8% patients died. In both unadjusted and adjusted Cox survival analysis, AVR was associated with improved survival (hazard ratio, 0.41; 95% CI, 0.34–0.51, P<0.001). Impact of AVR persisted when stratifying the cohort by symptom status and baseline aortic valve area (log rank, P<0.001 for both) and after propensity‐score matching (hazard ratio, 0.40; 95% CI, 0.32–0.50; P<0.001). In the longitudinal analysis, there were statistically significant changes over time in aortic valve peak gradient (P<0.001) and aortic valve area (P<0.001) and only mild increases in left ventricular end‐diastolic (P<0.007) and ‐systolic (P<0.001) volumes.

Conclusions

MAVD confers a high risk of all‐cause mortality. However, AVR significantly reduces this risk independent of aortic valve area, symptom status, and after controlling for confounding variables.

Machine Learning Prediction of Response to Cardiac Resynchronization Therapy: Improvement Versus Current Guidelines

BACKGROUND

Cardiac resynchronization therapy (CRT) has significant nonresponse rates. We assessed whether machine learning (ML) could predict CRT response beyond current guidelines.

METHODS

We analyzed CRT patients from Cleveland Clinic and Johns Hopkins. A training cohort was created from all Johns Hopkins patients and an equal number of randomly sampled Cleveland Clinic patients. All remaining patients comprised the testing cohort. Response was defined as ≥10% increase in left ventricular ejection fraction. ML models were developed to predict CRT response using different combinations of classification algorithms and clinical variable sets on the training cohort. The model with the highest area under the curve was evaluated on the testing cohort. Probability of response was used to predict survival free from a composite end point of death, heart transplant, or placement of left ventricular assist device. Predictions were compared with current guidelines.

RESULTS

Nine hundred twenty-five patients were included. On the training cohort (n=470: 235, Johns Hopkins; 235, Cleveland Clinic), the best ML model was a naive Bayes classifier including 9 variables (QRS morphology, QRS duration, New York Heart Association classification, left ventricular ejection fraction and end-diastolic diameter, sex, ischemic cardiomyopathy, atrial fibrillation, and epicardial left ventricular lead). On the testing cohort (n=455, Cleveland Clinic), ML demonstrated better response prediction than guidelines (area under the curve, 0.70 versus 0.65; P=0.012) and greater discrimination of event-free survival (concordance index, 0.61 versus 0.56; P<0.001). The fourth quartile of the ML model had the greatest risk of reaching the composite end point, whereas the first quartile had the least (hazard ratio, 0.34; P<0.001).

CONCLUSIONS

ML with 9 variables incrementally improved prediction of echocardiographic CRT response and survival beyond guidelines. Performance was not improved by incorporating more variables. The model offers potential for improved shared decision-making in CRT (online calculator: http://riskcalc.org:3838/CRTResponseScore ). Significant remaining limitations confirm the need to identify better variables to predict CRT response.

Characteristics and Outcomes in a Contemporary Group of Patients With Suspected Significant Mitral Stenosis Undergoing Treadmill Stress Echocardiography

Background:

In contemporary patients with suspected significant mitral stenosis (MS) undergoing rest and treadmill stress echocardiography, we assessed characteristics and factors associated with longer-term survival.

Methods:

We studied 515 consecutive patients (asymptomatic/atypical symptoms, mean left ventricular ejection fraction 58±2%; 43% male) with suspected at least moderate MS ([1] native mitral valve [MV]: resting mean MV gradient ≥5 mm Hg or area ≤1.5 cm 2 and [2] prosthetic valve: resting mean MV gradient ≥5 mm Hg or effective orifice area ≤2 cm) who underwent rest and treadmill stress echocardiography between 1/2003 and 12/2013. MS was categorized as rheumatic (n=170, 33%), postsurgical (prior mitral repair/replacement, n=245, 48%), and primary nonrheumatic (n=100, 19%). Primary outcome was all-cause mortality.

Results:

Mean resting MV gradient and right ventricular systolic pressure were 8.5±3 and 39±13 mm Hg. Patients achieved 95±29% age-sex predicted metabolic equivalents; peak-stress MV gradient and right ventricular systolic pressure were 17±7 and 61±14 mm Hg, respectively. At 54 days (median), 224 (44%) underwent invasive mitral procedure. At 6±4 years, 76 (15%) died. On survival analysis, primary nonrheumatic MS (hazard ratio [HR], 4.92), higher Society of Thoracic Surgeons score (HR, 1.92), lower % age-sex predicted metabolic equivalents (HR, 1.22), and higher peak-stress right ventricular systolic pressure (HR, 1.35), was associated with higher mortality, while invasive mitral procedures were associated with improved survival (HR, 0.67; all P <0.01).

Conclusions:

In asymptomatic patients (or with atypical symptoms) with significant MS undergoing treadmill stress echocardiography, higher mortality was associated with primary nonrheumatic MS, lower % age-sex predicted metabolic equivalents, and higher peak-stress right ventricular systolic pressure, while invasive MV procedures were associated with survival.

Teamwork using strain imaging in the echocardiographic assessment of right ventricular systolic function: A cardiac magnetic resonance imaging correlation study

AIM

The aim of this study was to investigate whether conventional echocardiographic assessment of right ventricular (RV) systolic function can be improved by the addition of RV strain imaging. Additionally, we also aimed to investigate whether dedicated reading sessions and education can improve echocardiographic interpretation of RV systolic function.

METHODS

Readers of varying expertise (staff echocardiologists, advanced cardiovascular imaging fellows, sonographers) assessed RV systolic function. In session 1, 20 readers graded RV function of 19 cases, using conventional measures. After dedicated education, in session 2, the same cases were reassessed, with the addition of RV strains. In session 3, 18 readers graded RV function of 20 additional cases, incorporating RV strains. Computer simulations were performed to obtain 230 random teams. RV ejection fraction (RVEF) by cardiac magnetic resonance (CMR) was the reference standard.

RESULTS

Correlation between RV GLS and CMR-derived RVEF was moderate: Spearman's rho: 0.70, n = 19, P < 0.001 (first two sessions); 0.55, n = 20, P < 0.05 (third session). Individual readers' assessment moderately correlated with RVEF (Spearman's rho first session: 0.67 ± 0.2; second session: 0.61 ± 0.2; and third session: 0.68 ± 0.09). Team estimates of RV systolic function showed consistently better correlation with RVEF, which were improved further by averaging across all readers. RV strain parameters influenced echocardiographic interpretation, with a net reclassification index of 8.0 ± 3.6% (P = 0.014).

CONCLUSIONS

The RV strain parameters showed moderate correlations with CMR-derived RVEF and appropriately influenced echocardiographic interpretation of RV systolic function. "Wisdom of the crowd" applied by averaging echocardiographic assessments of RV systolic function across teams of echocardiography readers, further improved echocardiographic assessment of RV systolic function.

Impact of abnormal longitudinal rotation on the assessment of right ventricular systolic function in patients with severe pulmonary hypertension

Background

Assessment of right ventricular (RV) function plays an important role in patients with cardiopulmonary disease, and current guidelines recommend parameters including tricuspid annular plane systolic excursion (TAPSE) and right ventricular systolic excursion velocity (RVS') to assess RV longitudinal function. We assessed the hypothesis that the previously undescribed motion of RV longitudinal rotation (RVLR) is an independent predictor of both TAPSE and RVS'.

Methods

We assessed a series of 100 consecutive patients with pulmonary hypertension (PH) undergoing echocardiography. Patients with left ventricular (LV) dilation and dysfunction were excluded. Standard RV parameters were determined using established guidelines, while RVLR and right ventricular global longitudinal strain (RVGLS) measurements were performed using 2-dimensional (2D) speckle tracking technique.

Results

Mean peak RVLR measured -4.2±3.7 degrees. By convention, negative values implied clockwise motion. In a multiple linear regression model, TAPSE could be predicted from a combination of RVLR and RVGLS (R=0.56, P<0.001). A similar relationship was found for RVS' which could also be predicted from a combination of RVLR and RVGLS (R=0.52, P<0.001). While no association was found between RVLR and RV size, estimated RV systolic pressure (RVSP) or the presence of a pericardial effusion, a mild correlation was noted between RVLR and QRS duration (R=0.25, P=0.01).

Conclusions

RVLR is an independent predictor of TAPSE and RVS'. Awareness of this motion should be considered in the interpretation of TAPSE and RVS' values as markers of RV systolic function, as abnormal RVLR may account for exaggerated values, particularly in patients with PH and RV dysfunction.