Pulse wave analysis (PWA) using applanation tonometry is a non-invasive technique for assessing cardiovascular function. It produces three important indices: ejection duration index (ED%), augmentation index adjusted for heart rate (AIX@75), and subendocardial viability ratio (SEVR%). The aim of this study was to assess within-and between-observer repeatability of these measurements. After resting supine for 15 minutes, 20 ambulant patients (16 male) in sinus rhythm underwent four PWA measurements on a single occasion. Two nurses (A & B) independently and alternately undertook PWA measurements using the same equipment (Omron HEM-757; SphygmoCor with Millar hand-held tonometer) blind to the other nurse's PWA measurements. Within-and between-observer differences were analysed using the Bland-Altman 'limits of agreement' approach (mean difference Ϯ 2 standard deviations, 2SD). Mean age was 56 (blood pressure, BP 136/79; pulse rate 64). BP/PWA measurements remained stable during assessment. Based on the average of two PWA measurements the mean Ϯ 2SD between-observer difference in ED% was 0.3 Ϯ 2.0; AIX@75 1.0 Ϯ 3.9; and SEVR% 1.7 Ϯ 14.2. Based on a single PWA measurement the between-observer difference was ED% 0.3 Ϯ 3.3; AIX@75 1.7 Ϯ 6.9; and SEVR% 0.6 Ϯ 22.6. Within-observer differences for nurse-A were ED% 0.0 Ϯ 5.4; AIX@75 1.5 Ϯ 7.0; and SEVR% 1.7 Ϯ 39.0 (nurse-B: 0.1 Ϯ 3.8; 0.1 Ϯ 8.0; and 0.6 Ϯ 23.3, respectively). PWA demonstrates high levels of repeatability even when used by relatively inexperienced staff and has the potential to be included in the routine cardiovascular assessment of ambulant patients. measurement of three main indices of cardiovascular function: augmentation index adjusted to a heart rate of 75 beats per minute (AIX@75), subendocardial viability ratio (SEVR%), and the ejection duration index (ED%). 1 The derivation of these indices are shown schematically in Figure 1 and described below. Augmentation index (AIX) adjusted to a heart rate of 75 (AIX@75)In the peripheral arteries the outgoing systolic pulse wave is reflected back towards the heart and adds to ('augments') the central aortic pressure in late systole. 1,[3][4][5] The amount by which the aortic pressure is increased by this phenomenon is the 'augmentation pressure' (AP). AIX is this aortic AP expressed as a percentage of the aortic 'pulse pressure' (PP). 1,3,4 AIX (ϭAP/PP) indicates the combined influence of large artery pulse wave velocity, peripheral pulse wave reflection and vascular function. 3,5,7,8 AIX is the most widely researched index of PWA, with several studies indicating that AIX is independently predictive of adverse cardiac events. 9,10 Since AIX varies with heart rate it is commonly adjusted to a 'standard heart rate' of 75 beats per minute (AIX@75). 11 Subendocardial viability ratio (SEVR%, Buckberg ratio)The 'area under the curve' (AUC) of the systolic and diastolic portions of the central aortic pulse wave can be measured using PWA. 1 Blood flow within the coronary arteries occurs mainly during diastol...

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Non-invasive assessment of central aortic pressures using PWA on a single occasion is highly repeatable in ambulant patients even when used by relatively inexperienced staff.

Even when undertaken by relatively inexperienced operators, both 'within' and 'between' observer repeatability of AIx measurement is very high. Such non-invasive assessment of arterial stiffness has the potential to be included in the clinical assessment of ambulant patients.

In patients with RA who are free of overt arterial disease, higher RA disability is associated with increased arterial stiffness independently of traditional cardiovascular risk factors and RA characteristics.