Earlier Intervention in Asymptomatic Chronic Aortic Regurgitation-Novel Indicators of Myocardial Overload

Valvular Heart Disease-A New Evolving Paradigm

Valvular heart disease is one of the most common cardiovascular diseases today and may result in severe limiting symptoms, a shortened lifespan, and, in some cases, sudden death. It is important to identify significant valve disease because intervention can restore quality of life and in many instances increase longevity. In most patients, the diagnosis of significant valvular heart disease can be made on the basis of a physical examination, yet nearly half of the patients who could benefit from interventions are not being recognized or referred. There have been major improvements in both the diagnosis and treatment of patients with valvular heart disease, with noninvasive echocardiography available to confirm the presence and severity of valve disease, better and more durable surgical procedures, and the advent of catheter-based therapies. There are now national guidelines to aid clinicians in the optimal timing of the intervention, which are presented. However, it is now recognized that the long-standing volume or pressure overload from valve disease can result in incipient ventricular dysfunction even before the onset of symptoms or a drop in ejection fraction; therefore, there is an impetus to recognize and to treat these patients earlier and earlier in the disease natural history. A shared decision-making process should play a key role in the final decision for therapy, outlining the goals and risks of possible intervention coupled with the patient's own needs and expectations.

Noninvasive Imaging for Native Aortic Valve Regurgitation

Aortic regurgitation (AR) is associated with left ventricular (LV) volume and pressure overload, resulting in eccentric LV remodeling and enlargement. This condition may be well tolerated for years before the onset of myocardial dysfunction and symptoms. Echocardiography plays a crucial role in the diagnosis of AR, assessing its mechanism and severity, and detecting LV remodeling. The assessment of AR severity is challenging and frequently requires the integration of information from multiple different measurements to assess the severity. Recent data suggest that echocardiographically derived LV volumes (end-systolic volume index > 45 mL/m2), an ejection fraction threshold of <60%, and abnormal global longitudinal strain may help identify early dysfunction and may be used to improve clinical outcomes. Consequently, these parameters can identify candidates for surgery. Cardiac magnetic resonance imaging is emerging as a valuable tool for assessing severity when it remains unclear after an echocardiographic evaluation. This review emphasizes the importance of imaging, particularly echocardiography, in the evaluation of AR. It focuses on various echocardiographic parameters, including technical details, and how to integrate them for assessing the mechanism and severity of AR as well as LV remodeling.

Machine Learning Identifies Clinically Distinct Phenotypes in Patients With Aortic Regurgitation

BACKGROUND

Aortic regurgitation (AR) is a prevalent valve disease with a long latent period before symptoms appear. Recent data has suggested the role of novel markers of myocardial overload in assessing onset of decompensation.

METHODS

The aim of this study was to evaluate the role of unsupervised cluster analyses in identifying different clinical clusters, including clinical status, and a large number of echocardiographic variables including left ventricular volumes, and their associations with mortality. Patients with moderate to severe or greater chronic AR identified using echocardiography at the Mayo Clinic in Rochester, Minnesota, were retrospectively analyzed. The primary outcome was all-cause mortality censored at aortic valve surgery. Uniform manifold approximation and projection with the k-means algorithm was used to cluster patients using clinical and echocardiographic variables at the time of presentation. Missing data were imputed using the multiple imputation by chained equations method. A supervised approach trained on the training set was used to find cluster membership in a hold-out validation set. Log-rank tests were used to assess differences in mortality rates among the clusters in both the training and validation sets.

RESULTS

Three distinct clusters were identified among 1,100 patients (log-rank P for survival < .001). Cluster 1 (n = 337), which included younger males with severe AR but fewer symptoms, showed the best survival at 75.6% (95% CI, 69.5%-82.3%). Cluster 2 (n = 235), including older patients and more females with elevated filling pressures, showed intermediate survival of 64.2% (95% CI, 56.8%-72.5%). Cluster 3 (n = 253), characterized by severe symptomatic AR, demonstrated the lowest survival of 45.3% (95% CI, 34.4%-59.8%) at 5 years. Similar clusters were identified in the internal validation cohort.

CONCLUSIONS

Distinct clusters with variable echocardiographic features and mortality differences exist within patients with chronic moderate to severe or greater AR. Recognizing these clusters can refine individual risk stratification and clinical decision-making after verification in future prospective studies.

Echocardiographic Markers of Early Left Ventricular Dysfunction in Asymptomatic Aortic Regurgitation: Is It Time to Change the Guidelines?

BACKGROUND

The ideal timing for surgery in asymptomatic chronic aortic regurgitation (AR) remains unclear. New thresholds for left ventricular ejection fraction (LVEF), left ventricular (LV) indexed end-systolic volume (iESV), and global longitudinal strain (GLS) have been associated with mortality in these patients. These represent markers of early LV dysfunction.

OBJECTIVES

The authors sought to assess the relationship between these markers (LVEF <60%, iESV ≥45 mL/m2, and GLS worse than -15%) and mortality, comparing them to Class I/IIa American College of Cardiology/American Heart Association guideline recommendations and absence of any of these.

METHODS

A total of 673 asymptomatic patients with chronic clinically significant (≥ moderate-severe) AR between 2004 and 2019 at a single referral center were retrospectively analyzed. The primary study outcome was all-cause mortality.

RESULTS

Mean age was 57 ± 17 years, 97 (14%) were female, 293 (45%) had hypertension, and 273 (41%) had an abnormal number of valve cusps. Aortic valve replacement was performed in 281 (48%) patients, and 69 (10%) died while under surveillance (without aortic valve replacement). LVEF <60% was present in 296 (44%) patients, 122 (25%) of 482 had GLS worse than -15%, and 261 (39%) had iESV ≥45 mL/m2. Mortality under surveillance was highest when Class I/IIa recommendations were present (HR: 4.22; 95% CI: 2.15-8.29), followed by the presence of 1 or more markers of early LV dysfunction (HR: 2.18; 95% CI: 1.21-3.92); no markers was used as the reference (all, P < 0.05). LVEF showed the strongest association with mortality, statistically slightly better than GLS and iESV. In the absence of Class I/IIa recommendations, 1 marker of early LV dysfunction was associated with higher, although not statistically significant, mortality compared with no markers (P = 0.063), followed by 2 markers; highest mortality was when all 3 markers were present (HR: 5.46; 95% CI: 2.51-11.90; P < 0.001).

CONCLUSIONS

Patients with asymptomatic clinically significant chronic AR incur a survival penalty when Class I/IIa guideline recommendations are attained. In patients without these recommendations, at least 2 markers of early LV dysfunction identify those with higher mortality risk who may benefit from early surgery.

Aortic Regurgitation: Review of the Diagnostic Criteria and the Management Guidelines

PURPOSE OF REVIEW

The evaluation of aortic regurgitation (AR) has advanced from physical examination and angiography towards evidence based non-invasive quantitative methods, primarily with echocardiography and more recently with cardiac magnetic resonance (CMR). This review highlights the guidelines and recent evidence in the diagnosis and management of AR; and outlines future areas of research.

RECENT FINDINGS

Contemporary large cohorts of AR patients studied with echocardiography and CMR suggest that the left ventricular remodeling and systolic function triggers for intervention may be lower than previously recommended in the guidelines and emphasize the importance of LV volumes in risk stratification. Important gaps of knowledge in the quantitation of AR severity and patient risk stratification were fulfilled recently. Potential thresholds for intervention using ventricular volumes and CMR quantitative findings were recently described. The criteria for what constitutes hemodynamically significant AR and the optimal timing of intervention AR deserve further study.

Aortic Regurgitation and Heart Failure: Advances in Diagnosis, Management, and Interventions

This review discusses the contemporary clinical evaluation and management of patients with comorbid aortic regurgitation (AR) and heart failure (HF) (AR-HF). Importantly, as clinical HF exists along the spectrum of AR severity, the present review also details novel strategies to detect early signs of HF before the clinical syndrome ensues. Indeed, there may be a vulnerable cohort of AR patients who benefit from early detection and management of HF. Additionally, while the mainstay of operative management for AR has historically been surgical aortic valve replacement, this review discusses alternate procedures that may be beneficial in high-risk cohorts.

Influence of Cardiac Remodeling on Clinical Outcomes in Patients With Aortic Regurgitation

BACKGROUND

Quantitative cardiac magnetic resonance (CMR) outcome studies in aortic regurgitation (AR) are few. It is unclear if volume measurements are beneficial over diameters.

OBJECTIVES

This study sought to evaluate the association of CMR quantitative thresholds and outcomes in AR patients.

METHODS

In a multicenter study, asymptomatic patients with moderate or severe AR on CMR with preserved left ventricular ejection fraction (LVEF) were evaluated. Primary outcome was development of symptoms or decrease in LVEF to <50%, development of guideline indications for surgery based on LV dimensions, or death under medical management. Secondary outcome was the same as the primary outcome, excluding surgery for remodeling indications. We excluded patients who underwent surgery within 30 days of CMR. Receiver-operating characteristic analyses for the association with outcomes were performed.

RESULTS

We studied 458 patients (median age: 60 years; IQR: 46-70 years). During a median follow-up of 2.4 years (IQR: 0.9-5.3 years), 133 events occurred. Optimal thresholds were regurgitant volume of 47 mL and regurgitant fraction of 43%, indexed LV end-systolic (iLVES) volume of 43 mL/m2, indexed LV end-diastolic volume of 109 mL/m2, and iLVES diameter of 2 cm/m2. In multivariable regression analysis, iLVES volume of ≥43 mL/m2 (HR: 2.53; 95% CI: 1.75-3.66; P < 0.001) and indexed LV end-diastolic volume of ≥109 mL/m2 were independently associated with the outcomes and provided additional discrimination improvement over iLVES diameter, whereas iLVES diameter was independently associated with the primary outcome but not the secondary outcome.

CONCLUSIONS

In asymptomatic AR patients with preserved LVEF, CMR findings can be used to guide management. CMR-based LVES volume assessment performed favorably compared to LV diameters.