P1371 The effect of ideal BSA in patients with low-flow, low-gradient severe aortic stenosis

INTRODUCTION

The current obesity epidemic has an impact on calculated BSA, significantly increasing the calculated BSA from what the ideal BSA would be if based on a patient’s ideal body weight.

PURPOSE

To determine the effect of ideal BSA on AV area index in patients with low-flow, low-gradient severe aortic stenosis and normal left ventricular function.

METHODS

Our ECHO database was searched for all patients with an LVEF >50%, a mean aortic gradient of <40 mmHg, an AV area <1.00cm2, AVA index <0.60cm2/m2 and SV index <35ml/m2. Patients with atrial fibrillation, mechanical and bioprosthetic valves, any valve repair, HOCM, Amyloidosis, more than mild aortic regurgitation, moderate mitral regurgitation, any wall motion abnormality despite normal LVEF, Pacemaker or ICD or a moderate pericardial effusion were excluded. Ideal weight was calculated using the Devine formula = Constant + 2.3 x [height in inches-60], where constant= 50Kg in males and 45.5Kg in females). Body surface area in m2 was calculated using the formula = [√ (height in cm x weight in kg)/3600]. The paired t-test was used to determine differences between means and the Fisher’s exact test was used to determine differences between proportions. A p value of <0.05 was considered significant.

RESULTS

There were 73 females (mean age 76.2 ± 11.3 years, mean AV gradient 27.2 ± 7.4 mmHg, mean AVA 0.82 ± 0.11 cm2 and mean LVEF of 64.9 ± 5.4%) and 55 males (mean age 76.1 ± 9.8 years, mean AV gradient 29.9 ± 7.2 mmHg, mean AVA 0.85 ± 0.11 cm2and mean LVEF of 62.2 ± 5.7%). Other important variables are seen in table 1. Based on the corrected ideal BSA there were 0 of 55 male patients who were re-assigned to the moderate AS category, compared to 25 of 73 (34.2%) female patients (P < 0.0001, Fisher’s exact test).

CONCLUSIONS

Use of the corrected ideal BSA has no effect on the hemodynamic diagnosis of low-flow, low gradient, normal LVEF severe aortic stenosis in males, but has a significant effect of the same diagnosis in females. It is therefore recommended that ideal body weight and ideal BSA be used when calculating AVA index in female patients suspected of low-flow, low-gradient severe aortic stenosis with normal ventricular function.

Weight(M) Weight(F) BSA(M) BSA(F) AVAI(M) AVAI(F) SVI(M) SVI(F) Actual 82.6 ± 12.5 70.1 ± 13.5 1.95 ± 0.15 1.71 ± 0.16 0.44 ± 0.06 0.48 ± 0.07 25.9 ± 4.9 23.9 ± 5.1 Ideal 67.5 ± 6.8 49.7 ± 5.4 1.79 ± 0.13 1.47 ± 0.11 0.48 ± 0.07 0.56 ± 0.08 28.3 ± 5.5 27.7 ± 6.3 P value <0.0001 <0.0001 <0.0001 <0.0001 <0.0001 <0.0001 <0.0001 <0.0001 (M)=male, (F)=female, weight in kg, BSA in m2, AVAI in cm2/m2, SVI in ml/m2.

P296 The effect of ideal BSA in patients with moderate aortic stenosis?

INTRODUCTION

The current obesity epidemic has an impact on calculated BSA. Obesity significantly increases the calculated BSA from what the ideal BSA would be if based on a patient’s ideal body weight.

PURPOSE

To determine the effect of ideal BSA on AV area index in patients with moderate aortic stenosis and normal left ventricular function.

METHODS

Our ECHO database was searched for all patients with an LVEF >50% and moderate aortic stenosis based on a mean aortic gradient of 20-39 mmHg and an AV area >1.00 cm2. Patients with more than mild aortic regurgitation, previous valvular repair or replacement, significant mitral valve disease or any LV wall motion abnormalities were excluded. Ideal weight was calculated using the Devine formula = Constant + 2.3 x [height in inches-60], where constant= 50Kg in males and 45.5Kg in females). Body surface area in m2 was calculated using the formula = [√ (height in cm x weight in Kg)/3600]. The paired t-test was used to determine differences between means and the Fisher’s exact test was used to determine differences between proportions. A p value of <0.05 was considered significant.

RESULTS

There were 210 females (mean age 75.4 ± 11.9 years, mean AV gradient 25.3 ± 4.8 mmHg, mean AVA 1.28 ± 0.27 cm2) and 385 males (mean age 72.7 ± 11.3 years, mean AV gradient 25.9 ± 5.2 mmHg, mean AVA 1.32 ± 0.28 cm2). Other important variables are seen in table 1. There were highly significant differences between actual and ideal measurements of weight, BSA and AV area index. Based on the actual BSA there were 151 of 385 male patients (39.2%) with severe aortic stenosis (<0.60 cm2/m2), which dropped to 66 of 385 patients (17.1%) when the ideal BSA was used in the calculation (P < 0.0001, Fisher’s exact test). For females there were 44 of 210 patients with severe aortic stenosis (21.0%) which dropped to 3 (1.4%) when the ideal BSA was used in the calculation (P < 0.0001, Fisher’s exact test).

CONCLUSIONS

Use of the ideal BSA, based on ideal weight, significantly reclassifies women in terms of AS severity and will be consistent throughout time. All mean aortic gradients and AV areas, by definition, and 98.6% of the ideal AV area indices being in the moderate AS range. The data is less compelling in males but is still significantly improved with 82.9% of AV area indices being correctly assigned.

Table 1. Weight/kg (Females) Weight/kg (Males) BSA/m2 (Females) BSA/m2 (Males) AVAI (Females) AVAI (Males) Actual. 77.5 ± 21.4 90.1 ± 16.9 1.79 ± 0.23 2.04 ± 0.20 0.72 ± 0.16 0.65 ± 0.14 Ideal. 51.6 ± 6.2 69.3 ± 7.1 1.51 ± 0.12 1.83 ± 0.14 0.85 ± 0.17 0.73 ± 0.16 P value. <0.0001 <0.0001 <0.0001 <0.0001 <0.0001 <0.0001 AVAI = Aortic valve area index (cm2/m2). BSA = Body surface area (m2).

P758 Should ECHO measurements be indexed to ideal BSA or actual BSA?

INTRODUCTION

A patient with aortic stenosis with an AVA of 1.22 cm2 who stands 5’ 6" and weighs 145 lb has a BSA of 1.76m2 (AV area index = 0.69 cm2/m2). If the same patient weighs 200 lbs, the BSA increases to 2.09 m2 (AV area index 0.58 cm2/m2). Their calculated AV area index therefore changes from the moderate range to the severe range.

PURPOSE

To determine from our ECHO database the effect the current obesity epidemic has on all ECHO variables that are indexed to BSA.

METHODS

Our ECHO database was searched for all patients with the required data variables, gender, age, height (cm)and body weight (kg) were required. Duplicate patients with multiple ECHO studies were removed, only the first ECHO entry being included. Obvious data entry errors were removed (e.g. height 1866 cm, or weight 8.6 kg). Ideal weight was calculated using the Devine formula, ideal weight = Constant + 2.3x[height in inches-60], where constant= 50kg in males and 45.5kg in females. Body surface area in m2 was calculated = [√(height in cm x weight in Kg)/3600]. The paired t-test was used to determine differences between means. A p value of <0.05 was considered significant.

RESULTS

There were 47,761 ECHO studies entered into the database, of which 46,605 (98%) had all the required fields completed. Once duplicates were removed (-15,903) and erroneous data deleted (-158, 0.33%), 30,536 remained. There were 16,160 females aged 58.7 ± 19.2 years, with a mean height of 161.7 ± 7.2cm and 14,376 males aged 59.8 ± 19.2 years, with a mean height of 176.7 ± 7.6 cm. There were statistically significant differences in both men and women between actual and ideal weight and actual and ideal BSA, see Table 1.

CONLUSIONS. For all ECHO measurements where the value is frequently indexed a decision needs to be made to either use the actual BSA or the ideal BSA. It may be more practical to use the ideal BSA which will remain consistent throughout follow up. Using our data any such measurement for females could be multiplied by 1.16 and for males 1.11 (i.e. actual BSA/ideal BSA). It is disappointing to find that, on average, females are 20 kilograms and males 18 kilograms above their ideal weight.

Table 1. Weight females (kg) Weight males (kg) BSA females (m2) BSA males (m2) Number. 16,160 14,376 16,160 14,376 Actual. 73.2 ± 18.9 89.1 ± 19.3 1.80 ± 0.24 2.08 ± 0.24 Ideal. 53.4 ± 6.5 71.4 ± 6.9 1.55 ± 0.13 1.87 ± 0.3 P value. <0.0001 <0.0001 <0.0001 <0.0001 BSA = Body surface area.

Differential effects of pentaerythritol tetranitrate and nitroglycerin on the development of tolerance and evidence of lipid peroxidation: a human in vivo study

OBJECTIVES

We investigated the development of nitrate tolerance after continuous exposure to nitroglycerin (GTN) as compared with pentaerythritol tetranitrate (PETN) in humans.

BACKGROUND

Sustained therapy with GTN causes tolerance and has been associated with increased production of free oxygen radicals by the endothelium. Pentaerythritol tetranitrate is an organic nitrate that has been used in the therapy of angina. There have been no investigations concerning the development of tolerance to PETN in humans. Animal investigations suggested that continuous therapy with PETN does not cause increased free radical production or hemodynamic tolerance.

METHODS

We randomized 30 healthy volunteers to continuous GTN (0.6 mg/h/24 h), long-acting PETN (60 mg orally three times a day) or no treatment (control group) for seven days. We studied systemic blood pressure responses and venous volume responses to GTN with strain-gauge plethysmography. The levels of cytotoxic aldehydes and isoprostanes were measured as markers of free radical-mediated lipid peroxidation.

RESULTS

Tolerance, as demonstrated by blood pressure and forearm plethysmography, developed in the GTN group and was absent in the PETN group (p < 0.05). Therapy with GTN was associated with a significant increase in plasma markers of lipid peroxidation. This response was not observed in those treated with PETN (isoprostanes: control: 38 +/- 5; GTN: 59 +/- 6; PETN: 38 +/- 3 microg/ml; p < 0.005).

CONCLUSIONS

Treatment with PETN does not cause tolerance and is not associated with evidence of increased free radical production.