June 17, 2014Open Access

Aortic stiffness as a marker of cardiac function and myocardial strain in patients undergoing aortic valve replacement

Structured PICO

Does high aortic pulse wave velocity predict worse cardiac function and myocardial strain in patients undergoing aortic valve replacement for aortic stenosis?

Population

56 adults (mean age 71 ± 8.4 years, 71.4% male) undergoing aortic valve replacement (AVR) for moderate to severe aortic stenosis. Exclusions: history of or presentation with aortic dissection, thoracic or abdominal aortic aneurysm, Marfan's syndrome, or chronic kidney disease.

Intervention

High aortic pulse wave velocity (PWV-high), defined as PWV above the normal age-standardized reference values, measured via automatic applanation tonometry.

Comparator

Normal aortic pulse wave velocity (PWV-norm), defined as PWV equal to or below normal age-standardized reference values.

Outcome

Correlation of PWV with NYHA functional class, left ventricular (LV) function, and B-type natriuretic peptide (BNP) levels pre-operatively and post-operatively (at 409 ± 159 days follow-up).surrogate

Aortic pulse wave velocity is an independent predictor of pre- and post-operative NYHA functional class in patients undergoing aortic valve replacement, suggesting its potential utility as a non-invasive marker of clinical functional status.

Abstract

BACKGROUND: Cardiac function and myocardial strain are affected by cardiac afterload, which is in part due to the stiffness of the aortic wall. In this study, we hypothesize that aortic pulse wave velocity (PWV) as a marker of aortic stiffness correlates with conventional clinical and biochemical markers of cardiac function and perioperative myocardial strain in aortic valve replacement (AVR). METHODS: Patients undergoing AVR for aortic stenosis between June 2010 and August 2012 were recruited for inclusion in this study. PWV, NYHA class and left ventricular (LV) function were assessed pre-operatively. PWV was analysed both as a continuous and dichotomous variable according to age-standardized reference values. B-type natriuretic peptide (BNP) was measured pre-operatively, and at 3 h and 18-24 h after cardiopulmonary bypass (CPB). NYHA class, leg edema, and LV function were recorded at follow-up (409 ± 159 days). RESULTS: Fifty-six patients (16 females) with a mean age of 71 ± 8.4 years were included, with 50 (89%) patients completing follow-up. The NYHA class of PWV-norm patients was significantly lower than PWV-high patients both pre- and post-operatively. Multiple logistic regression also highlighted PWV-cut off as an independent predictor of NYHA class pre- and post-operatively (OR 8.3, 95% CI 2.27,33.33 and OR 14.44, 95% CI 1.49,139.31 respectively). No significant relationship was observed between PWV and either LV function or plasma BNP. CONCLUSION: In patients undergoing AVR for aortic stenosis, PWV is independently related to pre- and post-operative NYHA class but not to LV function or BNP. These findings provisionally support the use of perioperative PWV as a non-invasive marker of clinical functional status, which when used in conjunction with biomarkers of myocardial strain such as BNP, may provide a holistic functional assessment of patients undergoing aortic valve surgery. However, in order for PWV assessment to be translated into clinical practice and utilised as more than simply a research tool, further validation is required in the form of larger prospective studies specifically designed to assess the relationship between PWV and these functional clinical outcomes.

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