ORIGINAL ARTICLE Survival by stroke volume index in patients with low-gradient normal EF severe aortic stenosis Mackram F Eleid, 1 Paul Sorajja, 1 Hector I Michelena, 1 Joseph F Malouf, 1 Christopher G Scott, 2 Patricia A Pellikka 1 1 Divisions of Cardiovascular Diseases, Mayo Clinic College of Medicine, Rochester, Minnesota, USA 2 Divisions of Biostatistics, Mayo Clinic College of Medicine, Rochester, Minnesota, USA Correspondence to Dr Mackram F Eleid, Division of Cardiovascular Diseases, Mayo Clinic College of Medicine, 200 First St. SW, Rochester, MN 55905, USA; eleid.mackram@mayo.edu Received 5 May 2014 Revised 23 August 2014 Accepted 25 August 2014 Published Online First 12 September 2014 ▸ http://dx.doi.org/10.1136/ heartjnl-2014-306677 ▸ http://dx.doi.org/10.1136/ heartjnl-2014-306933 To cite: Eleid MF, Sorajja P, Michelena HI, et al. Heart 2015;101:23–29. ABSTRACT Objective Low-gradient (LG) severe aortic stenosis (AS) and preserved EF with reduced stroke volume are associated with an adverse prognosis, but the relationship of stroke volume index (SVI) with mortality among a range of values is unknown. We investigated the prognostic impact of SVI in this population. Methods We examined 405 consecutive patients with preserved EF (≥50%) and severe AS (valve area <1.0 cm 2 ) with LG (<40 mm Hg) using echocardiography. Patients were stratified into quartiles based on SVI distribution (group 1: <38 mL/m 2 (n=90), group 2: 38–43 mL/m 2 (n=105), group 3: 43–48 mL/m 2 (n=104) and group 4: >48 mL/m 2 (n=106)). Results Groups 1 and 2 had poorer survival with medical management compared with 3 and 4 (3-year estimate 46% and 67% vs. 78% and 73%, respectively, p=0.002) although aortic valve replacement referral rate was similar (53%–62%, p=0.57). An inverse relationship was observed between SVI and mortality (HR 1.28 (1.11 to 1.46) per every 5 mL/m 2 decrease in SVI). After multivariable analysis, SVI was the strongest predictor of mortality (HR 0.92 (0.89 to 0.95), p<0.0001). Using different SVI cutpoints, SVI <35 was associated with highest mortality (HR 2.36 (1.49 to 3.73), p<0.001), followed by SVI <38 (HR 2.09 (1.39 to 3.16), p<0.001) and by SVI <43 (HR 2.05 (1.38 to 3.05), p<0.001). Survival with SVI ≥43 was similar to age and sex-matched controls (3-year estimate 84%, p=0.24); survival for SVI <43 was significantly worse (3-year estimate 63%, p<0.001). Conclusions Lower SVI is incrementally associated with mortality in LG severe AS with preserved EF. These findings have implications for classification of AS severity, identification of high-risk groups and subsequent management. INTRODUCTION Low flow, low-gradient (LG) severe aortic stenosis (AS) with preserved EF is a recently described syn- drome associated with reduced survival. 1–6 The mechanism of low stroke volume (SV) has been attributed to reduced systemic arterial compliance (SAC), smaller LV cavity size due to concentric remodelling, restrictive physiology resulting in impaired LV filling and diminished LV systolic func- tion despite preserved EF. 7 In order to improve AS assessment and determine the optimal treatment strategy, a new flow-gradient classification has been proposed incorporating the mean aortic valve gra- dient along with normal vs. reduced stroke volume index (SVI). 5 Studies have arbitrarily used a cut- point of SVI <35 mL/m 2 to define the low flow group; 1–6 however, other cutpoints have not been investigated, and whether SVI has a graded rela- tionship for predicting outcome in this group of patients is unknown. We have recently investigated the prevalence of flow-gradient patterns in severe AS with preserved EF at our own institution and found that SVI <35 mL/m 2 is strongly predictive of poor outcome in patients with LG severe AS and preserved EF. 8 We hypothesised that lower SVI may have a graded association with mortality and that such knowledge may improve risk prediction in this population. Accordingly, we investigated the prog- nostic impact of SVI among a range of values in a population of patients with LG severe AS with pre- served EF. METHODS Patients The Mayo Clinic Institutional Review Board approved this cohort study. Consecutive patients aged ≥18 years who underwent transthoracic echo- cardiography between 1 January 2006 and 31 December 2011 with the following criteria were enrolled: (1) aortic valve area (AVA) <1.0cm 2 , (2) preserved LV EF (≥50%), (3) LG (mean gradient <40 mm Hg) and (4) absence of prosthetic valves, complex congenital heart disease, supravalvular or subvalvular AS, hypertrophic cardiomyopathy, and concomitant moderate or severe native valvular lesions. These criteria led to a final study popula- tion of 405 patients. The medical record was manually reviewed for symptoms, comorbidities and laboratory data. 2D and Doppler echocardiography Comprehensive 2D and Doppler echocardiographic studies were performed on commercially available ultrasound equipment (Acuson Sequoia, Siemens Medical, Mountain View, California, USA; Vivid-7, GE Healthcare, Milwaukee, Wisconsin, USA; and IE33, Phillips Healthcare, Andover, Massachusetts, USA) in accordance with the American Society of Echocardiography guidelines. 9 10 Blood pressure was measured by manual sphygmomanometer and cardiac rhythm measured by electrocardiography at the time of echocardiography. EF was measured using the modified 2D Quinones formula or biplane method of disks. LV outflow tract diameter was measured in the parasternal long axis view in early systole from the point of aortic cusp insertion into the interventricular septum to the point of Editor’s choice Scan to access more free content Valvular heart disease Eleid MF, et al. 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