Chronic Severe Aortic Regurgitation: Should We Lower Operating Thresholds?

Milind Y. Desai, MD; Lars G. Svensson, MD, PhD


Circulation. 2019;140(12):1045-1047. 

Chronic severe aortic regurgitation (AR) results in left ventricular (LV) volume and pressure overload, initially leading to compensatory but eventually detrimental myocardial changes, with patients remaining asymptomatic for a long time. Over time, the LV fails, resulting in a reduction in left ventricular ejection fraction (LVEF) and symptom onset. Current American College of Cardiology/American Heart Association guidelines recommend aortic valve (AV) surgery in symptomatic patients or those with depressed LVEF (Class I indication).[1] They also recommend AV surgery (Class II indication) in asymptomatic patients with preserved LVEF and a significantly dilated LV.[1] However, these recommendations were derived from smaller studies, performed at a time when surgical outcomes were poorer. With significant improvements in imaging, advanced surgical techniques (minimally invasive surgery, AV repair, improved intraoperative myocardial protection and postoperative care), surgical outcomes have improved considerably. Multiple recent reports have suggested that the previously recommended LV size thresholds for recommending AV surgery may be too conservative.[2–4] Hence, is it time for the current guidelines to be revisited in terms of making recommendations for earlier AV surgery for asymptomatic patients with severe AR and a preserved LVEF?

In a study of 1417 patients treated at a high-volume center, patients with ≥III+ AR (±concomitant aortopathy) and preserved LVEF (87% asymptomatic and 13% with mild symptoms) demonstrated significantly improved longer-term survival following AV surgery (n=933, 58% with concomitant aortic replacement, 0.2% in-hospital mortality for isolated AV surgery) which approximates that of a normal age-gender-matched US population (Figure 1A).[2] The finding was independent of the indexed LV end-systolic dimension (iLVESD) at which the patient was operated. Furthermore, in the 484 nonoperated patients, those with iLVESD ≤2.0 cm/m2 had an excellent 5-year survival; however, the risk of death increased once iLVESD exceeded 2.0 cm/m2 (Figure 1B). These findings were further corroborated in an independent sample of 356 patients undergoing AV surgery (1.1% in-hospital mortality).[3] In the study, adjusted 10-year survival was better among patients without operative triggers (89±4%) or with Class II triggers (85±6%) than in patients with Class I triggers (71±4%, P<0.01). In addition, the authors also demonstrated that the mortality started to increase for LVEF <55% and iLVESD >2.0 to 2.2 cm/m2 (Figure 1C). A third independent report on 748 patients (of which 361 underwent AV surgery with a <1% in-hospital postoperative mortality) with chronic severe AR also demonstrated that operating for class I indication was associated with worse longer-term mortality as compared to Class II indication.[4] In addition, iLVESD beyond which mortality increased was also 2 cm/m2 (Figure 1D).


Recent data on chronic severe aortic regurgitation.
A, Improved outcomes, similar to normal age-gender matched US population, of patients with chronic severe aortic regurgitation undergoing AV surgery vs not2 (B through D). Spline curves demonstrating that mortality increased past iLVESD threshold of 2 cm/m22–4. AV indicates aortic valve; and iLVSED, indexed left ventricular end systolic dimension.

However, before recommending earlier AV surgery, especially in patients with preserved LVEF and only a mildly dilated LV, we strongly advocate further refinement in techniques to identify higher risk individuals. This would enable us to identify predisposed individuals that would truly benefit from an earlier surgery. One of the key things that should be ascertained is a consistent grading of AR severity, using a multi-parametric echocardiographic approach. In addition, cardiac magnetic resonance can provide complementary information with regards to AR quantification, in addition to precise LV size and function assessment. However, the cardiac magnetic resonance techniques need to be standardized and appropriate thresholds (both for LV size and AR severity) developed, while recognizing that the thresholds of AR severity are different in cardiac magnetic resonance and echocardiography.

In addition, there should be an impetus on identifying more sensitive markers for detecting a predisposed individual with severe AR and preserved LVEF who would benefit from earlier AV surgery.[5] Biomarkers such as brain natriuretic peptide (and high-sensitivity troponin) could also help earliesr detection of predisposed individuals. Stress echocardiography helps identify some predisposed individuals who underrecognize their symptoms and could potentially help better optimize surgical timing. Additional imaging markers such as global longitudinal strain on speckle tracking echocardiography or myocardial fibrosis (focal or regional) measured on cardiac magnetic resonance can also provide incremental prognostic value and help earlier identification of a predisposed patient, prior to onset of irreversible myocardial damage.

We believe that the field has come to a point where we potentially need to revisit the current guidelines in terms of making recommendations for earlier (iLVESD is >2.0 cm/m2) AV surgery (repair or replacement) for asymptomatic patients with severe AR and a preserved LVEF. However, any potential earlier indication for AV surgery, including that with concomitant aortic disease, must be put in the context of an experienced team that comprises cardiologists and cardiac surgeons, practicing at a center of excellence with advanced imaging and high-quality perioperative care. We also need prospective randomized trials.