|Author, date and country||Patient group||Study type (level of evidence)||Outcomes||Key results||Study Weaknesses|
|Monin et al,|
|6 center study with prospective enrolment of 136 patients with aortic stenosis-median aortic valve area of 0.7cm2 , median transaortic gradient of 29mmHg and median cardiac index of 2.11L/min/m2. Patients divided into 2 groups based on DSE-group I (n=92) with contractile reserve- and group II(n=44) with no contractile reserve. 70% of patients in both groups had AVR -64 of 92 in group I and 31 of 44 in group II.||Cohort study (Level 2b)||Peri-operative mortality||Group I-5%-3 of 64 patients. Group II-32%-10 of 31 patients.||Number of patients in the group with no contractile reserve who underwent AVR still small though larger than in previous studies.|
Observational study-patients not randomized.
|Long term survival||Group I-Estimated 3 year survival of 79% after AVR, and 20% without AVR. Group II-around 35% after AVR , and 10% without AVR|
|Post operative functional improvement||Group I- in 84% -54 of 64 patients. Group II- in 45%-14 of 31 patients.|
|Monin et al,|
|Low-dose DSE in 45 patients with median age 75, LVEF 29%, aortic valve area 0.7cm2 and mean transaortic gradient 26mmHg. Patients divided into 2 groups-group I with LV contractile reserve on DSE(n=32) and group II with no LV contractile reserve on DSE(n=13). AVR performed in 24 patients in group I and 6 in group II.||Cohort study (Level 2b)||Peri-operative mortality||Group I- 8% (2 of 24 patients) Group II- 50% (3 of 6 patients) (p=0.014).||Very small number of patients –only 6 patients in the group with no contractile reserve that underwent AVR.|
|Long term survival||Group I- 88%(21 of 24 patients) in those who had AVR. |
Group II- 1 of the 3 survivors died at 3 months. No data available about the outcome of the remaining 2 patients.
|Post operative functional improvement||Group I- Marked improvement in functional class - 17 patients initially in NYHA class III/IV compared to only 1 patient in class III at follow up (p=0.001). |
GroupII-Improvement in NYHA functional class from IV to III in 1 patient while the other remained in class III.
|Quere et al, |
|66 patients with low gradient (MPG<40mmHG), severe aortic stenosis (AVA< 1cm2) with an EF < 40% prospectively enrolled in (2) underwent AVR after dobutamine stress evaluation. Preoperative contractile reserve present in 46 patients (group I; 70%) and absent in 20 patients (group II 30%). Left ventricular ejection fraction calculated in all 66 patients before AVR and after the 30 day post operative period. Follow up clinical data obtained in all patients at a mean interval of 26+ 20 months.||Sub analysis of a prospective cohort study (level 2b)||Operative Mortality||Group I – 3 of 50 (6%). Group II – 10 of 30 (30%)||Well performed prospective cohort study (The French Multicentre study on low gradient AS)|
|Postoperative functional improvement in those who survived||Group I-96% (44/46) improved by > 1 functional class and 59% (27/46) improved by > 2 functional classes after AVR.|
Group II-90% (18/20) ) improved by > 1 functional class (p=0.35 versus group 1) and 55%(11/20) improved by > 2 functional classes after AVR(p=0.50 versus group I).
|Postoperative improvement in ejection fraction in those who survived.||Group I-LVEF increased from 28+ 6% to 47+ 11% (p<0.0001) with a mean increase of 19+10%. |
Group II-LVEF increased from 31+ 6% to 48+ 11% (p=0.0001) with a mean increase of 17+11%.
|Postoperative survival at 2 years assuming operative survival||Group I- 92+7% (p=0.63). Group II-90+5%|
|Nishimura et al, |
|32 patients with low-output, low-gradient aortic stenosis and EF<40% subjected to Dobutamine stress testing in the catheterization laboratory. Based on the results of the above, 21 patients underwent AVR. Patients who had AVR divided into 2 groups on the basis of presence or absence of a contractile response to dobutamine infusion-group I (n=15) with >20% increase in stroke volume and group II(n=6) with < 20% increase in stroke volume.||Cohort study (Level 2b)||Peri-operative mortality||Group I- 7%-1 of 15 patients. Group II- 33%-2 of 6 patients.||Very small number of patients –only 6 patients in the group with no contractile reserve that underwent AVR.|
|Late deaths||Group I-13.3%-2 of 15 patients- both non-cardiac . Group II-33%-2 of 6 patients -both cardiac-from heart failure at months 25 and 34 .|
|Post operative functional improvement||Group I- all 12 in NYHA I-II. Group II- 2 in NYHA I-II.|
|Bergler-Klein et al, TOPAS Study,|
|2002 to 2005 , 69 patients with low flow AS(EOA<0.6 cm2/m2 , mean grad <40mmHg, LVEF <40%), grouped into truly severe or pseudosevere AS by EOA <1.0 cm2 on dobutamine stress. Contractile reserve defined as an increase of SV >20%. BNP measured at regular intervals Surgery or medical therapy at discretion of physicians (29 AVR) 2 year follow up||Prospective Cohort study. (Level 2b)||Mortality||9 of 29 who had AVR (31%). 6 of 20 who had AVR with TS AS (30%). 3 of 9 who had AVR with PS AS (33%)|
11 of 40 medically treated pts (27%) 2 of 9 med treated TS AS (22%). 9 of 31 med treated PS AS (29%)
|The operative survival was not explicitly given for the subgroup with poor contractile reserve.|
This is (understandably) a small study for the sub-analyses performed
|BNP relationship to 30 day mortality in operated AS||19% if BNP>550pg/ml 8% if BNP <550pg.ml|
|Pts with poor or no contractile reserve (n=32)||50% mortality in high BNP group. 100% mortality in low BNP group|
1 year survival in patients with poor contractile reserve as as good as those with reserve as long as BNP <550pg/ml
|Bonnow et al, of Cardiology/ACC/AHA/Clinical Practice Guideline, |
|Systematic review of a wide range of issues in valvular heart disease This review updated a previous review conducted in 1998||Systematic review (level 1a)||Guideline recommendations||Patients in whom stroke volume fails to increase with dobutamine (less than 20% increase) appear to have a very poor prognosis with either medical or surgical therapy|
Dobutamine stress echocardiography is reasonable to evaluate patients with low-flow/low-gradient AS and LV dysfunction. (Level of Evidence: B)
Cardiac catheterization for hemodynamic measurements with infusion of dobutamine can be useful for evaluation of patients with low-flow/low-gradient AS and LV dysfunction. (Level of Evidence: C)
|Only 2 references given in support of this recommendation.|
|Vahania et al, European Society of Cardiology task force guidelines on management of VHD,|
|Systematic review of a wide range of issues in valvular heart disease||Systematic review (level 1a)||AVR in patients with severe aortic stenosis and no contractile reserve on stress testing||Patients in whom stroke volume fails to increase with dobutamine (less than 20% increase) appear to have a very poor prognosis with either medical or surgical therapySurgery can, nonetheless, be performed in these patients but decision-making should take into account clinical condition ( in particular, the presence of comorbidity), degree of valve calcification, extent of coronary disease, and feasibility of revascularisation.||Only 1 reference given in support of this recommendation|