Aortic Stenosis—New Insights
abstract & commentary
By Jonathan Abrams, MD
Professor of Medicine, Division of Cardiology, University of New Mexico, Albuquerque Dr. Abrams serves on the speaker’s bureau for Merck, Pfizer, and Parke-Davis.
Source: Pellikka PA, et al. Outcome of 622 Adults With Asymptomatic, Hemodynamically Significant Aortic Stenosis During Prolonged Follow-Up. Circulation. 2005;111:3290-3295.
This is a long-term observational report of a large Mayo Clinic cohort of patients with hemodynamically significant, but asymptomatic, aortic stenosis (AS). Their previous analysis of 113 of these patients with a mean follow-up of
20 months was published in 1990. This study consists of 622 adults seen at the Mayo Clinic, all over 40 years of age, and
with a peak systolic echo velocity > 4 m/s on Doppler echo.The study period was 1984 to 1995, with an initial population of 2800, reduced to 622 individuals with no other significant cardiac disease or who remained asymptomatic during follow-up. All patients were asked to return at 6 or 12 months. Clinical information was also obtained by a mailed questionnaire,
telephone interview, or review of medical records. The analysis included the probability of development of new cardiac
symptoms, the probability of death, and the probability of remaining free of cardiac death or aortic valve surgery. The
cohort had a mean age of 72 ± 11 years; approximately two-thirds were men. Mean aortic peak velocity was 4.4 ± 0.4 m/s, and the mean gradient was 46 ± 11, with a mean aortic valve
area (AVA) of 0.9 ± 0.2 cm². The duration of follow-up was a mean of 5.4 ± 4 years, during which 50% of the patients
developed symptoms of angina, dyspnea, or syncope. Freedom from cardiac symptoms was 82% at one year, 67% at 2
years, and 33% at 5 years. Valve area and the presence of LVH were independent predictors of symptom development. Fifty-seven percent of the entire cohort underwent
aortic valve surgery, of whom 221 developed symptoms and 131 remained asymptomatic. Thirty percent of the entire cohort died during follow-up, but only 19% were cardiac deaths. The
probability of remaining free of cardiac death and aortic valve surgery was 80% at one year,
63% at 2 years, and only 25% at 5 years. Age, renal failure, inactivity, and aortic valve velocity were
predictors of mortality. Of the entire group, 30% had a baseline peak velocity > 4.5 m/s. These individuals had a relative risk (CRR) of 1.3 for developing symptoms and a 1.5 RR for AV surgery or
cardiac death. There were 11 sudden deaths in patients who did not become symptomatic prior to
demise. In asymptomatic and unoperated patients, freedom from cardiac death was 99%, 98%, and 93% at one, 2, and 5 years. Pellikka and colleagues state, "the course of these patients was not benign," and "the likelihood of developing cardiac symptoms was high, with only 33% of the cohort remaining symptom-free and unoperated at 5 years." Also, "asymptomatic, severe AS has a small but real risk of sudden death." Predictors of symptoms included AVA and LVH. Risk factors for all cause mortality included age, chronic renal failure, inactivity, and aortic valve velocity. Pellikka et al conclude that clinical and echo characteristics were imperfect for identifying unoperated subjects at risk of death.
commentary
A 1997 study established an aortic velocity of > 4.0 m/s as severe AS. The current study identifies a velocity of > 4.5 m/s having the highest likelihood of symptoms; thus, the more severe the obstruction to outflow, the worse the outcome in this group of asymptomatic patients. Pellikka and colleagues suggest that a peak velocity > 4.5 m/s "might be considered for prophylactic aortic valve replacement." Surgery was highly protective in this study. Pellikka et al comment that mortality for aortic valve replacement today should be less than 5% at high volume centers; peri-operative mortality in the Mayo Clinic population was 1.4%. They state that most patients with severe, asymptomatic AS will develop symptoms within 5 years. AVA and LVH are predictors of symptoms. Sudden death without preceding symptoms was rare (approximately 1% per year) and cannot be predicted by clinical parameters.
This is a useful report that adds new information to several recent publications on AS. Follow-up was as long as 10 years, and the studied parameters in this population are quite familiar. In essence, an aortic peak velocity > 4 is a sensitive predictor in unoperated subjects at 5-year status; the Mayo Clinic suggests that a higher peak velocity, greater than 4.5, should trigger consideration of a prophylactic surgical strike. Previous studies have included other variables of outcome, but there is now a substantial database utilizing peak aortic velocity as an important discriminating factor. The present report has identified aortic valve area and LVH as particularly important characteristics associated with long-term outcomes. It would appear reasonable to consider aortic valve replacement in individuals with a very small valve area and the presence of LVH. All major outcomes, including unoperated, freedom from cardiac symptoms, freedom from cardiac death without surgery, remaining asymptomatic without surgery or death, demonstrate excellent outcomes at 1 to 2 years, but with a marked drop-off by the fifth year of follow-up of subjects remaining asymptomatic with freedom with cardiac death. In the true elderly, individuals that are virtually housebound, or the occasional patient with chronic renal failure, the use of aortic valve velocity may help with decision making. When symptoms occur, surgery is mandated for almost all individuals.
By Jonathan Abrams, MD Professor of Medicine, Division of Cardiology, University of New Mexico, Albuquerque Dr. Abrams serves on the speakers bureau for Merck, Pfizer, and Parke-Davis.You have reached your article limit for the month. Subscribe now to access this article plus other member-only content.
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