Survival after Aortic Valve Replacement for Aortic Regurgitation: Prediction from Preoperative Contractility Measurement

Abstract

Background: Noninvasive measurement of myocardial contractility (end-systolic wall stress-adjusted change in left ventricular ejection fraction from rest to exercise [ΔLVEF – ΔESS]) predicts heart failure, subnormal LVEF_rest, and sudden death in asymptomatic patients with chronic severe aortic regurgitation (AR). Here we assess the relation of preoperative ΔLVEF – ΔESS to survival after aortic valve replacement (AVR). Methods: Patients who underwent AVR for chronic, isolated, pure severe AR (n = 66) were followed for 13.0 ± 6.4 event-free years. Preoperative ΔLVEF – ΔESS (from combined echocardiographic and radionuclide cineangiographic data) enabled cohort stratification into 3 terciles (–1 to –11% [normal or mild] contractility deficit, –12 to –16% [moderate], and ≤–17% [severe], identical with segregation in our earlier study) to relate preoperative contractility to postoperative survival and to age- and gender-matched US census data. Results: Since AVR, 22 patients died (average annual risk [AAR] for all-cause mortality for the entire co hort = 3.15%). Preoperative ΔLVEF – ΔESS predicted postoperative survival (p = 0.009, log rank test). By contractility terciles, all-cause AARs were 1.44, 2.58, and 6.40%. Survival was lower than among US census comparators (p < 0.02), but the “mild” tercile was indistinguishable from census data (p = ns). By multivariable Cox regression, survival prediction by pre-AVR ΔLVEF – ΔESS was independent of, and superior to, prediction by age at surgery, gender, preoperative functional class, LVEF_rest, LVEF_exercise, change in LVEF_{rest to exercise}, and LV diastolic or systolic dimensions (p ≤ 0.01, pre-AVR ΔLVEF – ΔESS vs. other covariates). Conclusion: In severe AR, preoperative contractility predicts post-AVR survival and may be prognostically superior to clinical, geometric and performance descriptors, potentially impacting on patient selection for surgery.

Evaluation of Left Ventricular Performance: Is There a Gold Standard?

“…Borer et al [5], in this issue of Cardiology, present the long-term outcomes in patients with severe chronic AR, where a combination of several parameters related to LV function were used prior to aortic valve replacement. After the exclusion criteria, 66 patients were studied.…”

“…Patients were recruited from the Institute for Heart Valve Disease, which was established several decades ago in their Medical Center. LV ejection fraction at rest normalized for end-systolic stress and LV ejection fraction at peak exercise normalized for end-systolic stress at exercise were obtained in all patients [4][5][6][7]. From these measurements, changes in the LV ejection fraction from rest to exercise normalized for changes in end-systolic stress from rest to exercise were calculated.…”

“…During a 13 years follow-up period, 22 patients died. It was demonstrated that an abnormal response, as compared to normal, was associated with a poor prognosis [5]. The greater the deviation from normal values the worse the outcome.…”

“…The greater the deviation from normal values the worse the outcome. The authors concluded that determination of "contractility" in patients with chronic severe AR may be particularly useful in defining the optimal time for aortic valve replacement, since myocardial dysfunction may be present in these patients prior to symptom onset [5].…”

“…Borer et al [5] should be commended for this important work, where the best approach in patients with chronic AR has been used. This important work will help clinicians to define the optimal time for valve surgery in patients with chronic AR.…”