Prognostic implications of paradoxical low gradient severe aortic stenosis: a comprehensive analysis from a large multicentric registry

Background

Up to 40% of patients with severe aortic stenosis (SAS; indexed aortic valve area (AVAi) <0.6 cm2/m2) present with low transvalvular mean gradient (MG) despite a normal left ventricular ejection fraction (EF). There is intense debate about the prognostic significance of such entity, with some referring to it as an advanced form of the disease, others as an intermediate form between a moderate and a severe form.

Objectives

To compare outcome of patients with paradoxical low gradient SAS (PLG-SAS; i.e., mean gradient <40 mmHg and AVAi <0.6 cm2/m2) vs. moderate aortic stenosis (MAS; i.e. mean gradient <40 mmHg and AVAi >0.6 cm2/m2) and high gradient SAS (HG-SAS; i.e. mean gradient >40 mmHg and AVAi <0.6 cm2/m2).

Methods

2582 consecutive patients with aortic stenosis (PLG-SAS, n=933; MAS, n=876 and HG-SAS, n=773) and a preserved EF (>50%) from an international multicentric registry were studied. Five years mortality between groups was compared using Kaplan Meier analysis. Inverse probability weighting was used to adjust for clinical and imaging baseline characteristics. Additionally, to explore the impact of MG (<40 mmHg vs. >40 mmHg) in patients with AVAi <0.6 cm2/m2 (PLG-SAS vs. HG-SAS) and to explore the impact of AVAi (<0.6 cm2/m2 vs. >0.6 cm2/m2) in patients with MG <40 mmHg (PLG-SAS vs MAS) we performed 2 different propensity score analyses. Patients were censored at the time of surgery.

Results

Overall, during 23 [IQR,10–47] months of follow-up 1003 patients died and 770 patients underwent aortic valve replacement. IPW-adjusted natural history was significantly better in patients with MAS, intermediate for patients with PLG-SAS and worst in patients with HG-SAS (59 vs. 47 vs. 41%, p<0.001, see Figure 1A). Furthermore, at equal MG (448 pairs), survival was significantly better in patients with MAS compared with PLG-SAS (54% vs. 39% p<0.001, see Figure 1B) and at equal AVAi (377 pairs), survival was significantly better in patients with PLG-SAS compared with HG-SAS (43% vs. 32% p<0.001, see Figure 1C).

Conclusions

In this large multicentric cohort, survival of PLG-SAS patients was better than that of HG-SAS patients and worse than that of MAS patients. Furthermore, with a comparable mean gradient, the smaller the calculated AVAi, the worse the prognosis whereas with a comparable AVAi, the higher the mean gradient, the worse the prognosis. Taking together, these data demonstrate that PLG-SAS is an intermediate form in the disease continuum, HG-SAS being the most malignant form of AS.

Funding Acknowledgement

Type of funding sources: Public grant(s) – National budget only. Main funding source(s): Fonds National de la Recherche Scientifique (F.R.S.–FNRS)

Comparison of mitral regurgitant volume assessment between proximal flow convergence and volumetric methods in patients with significant primary mitral regurgitation

Funding Acknowledgements

Type of funding sources: None.

Background. Discrepancies have been observed between transthoracic echocardiography (TTE) and cardiac magnetic resonance imaging (MRI) severity grading in primary mitral regurgitation (MR).

Purpose. To compare mitral regurgitant volume (RV) obtained by the proximal flow convergence method (PISA) method by TTE and by volumetric methods (TTE and MRI), and study the relationship between LV size and RV obtained by either the PISA or volumetric methods.

Methods and results. 188 patients from 2 heart valve clinics with at least moderate-to-severe primary MR due to prolapse in sinus rhythm who underwent evaluation with TTE and MRI were included. RV was estimated by either PISA or volumetric methods (Left ventricular [LV] stroke volume minus systolic aortic outflow volume)) by either MRI (MRI-RV) or TTE (TTE-RV)). PISA-RV and either MRI-RV or TTE-RV weakly correlated (r = 0.29 and 0.30,p < 0.001). On multivariable analysis, LV end-diastolic volume (LVEDV) and bileaflet prolapse independently correlated with the magnitude of the difference between PISA and volumetric methods. While PISA-RV and LVEDV were unrelated, MRI-RV and TTE-RV strongly correlated with LVEDV (r = 0.66 and 0.68,p < 0.001). In contrast, LVEDV and regurgitant fraction (RF = RV/LVEDV) either with TTE or MRI were poorly related (r = 0.17,p = 0.02 and r = 0.12,p = 0.10).

Conclusion. RV estimated by the PISA and volumetric methods are not comparable. The expected proportional relationship between volumetric RV and LV size, which is not observed with PISA-RV suggests the inaccuracy of PISA-RV. Given that RV by volumetric methods depends on LV size, determination of a unique RV threshold for severe MR is challenging. Calculation of RF may overcome this limitation. Abstract Figure. RV assessed by PISA or volumetric method  Abstract Figure. Illustrative example

Impact of sex on management and survival in aortic stenosis

Background

Increasing attention has been paid to differences between the sexes in recent studies, but only a few have focused on such differences in aortic stenosis (AS).

Purpose

We sought to evaluate the differences between genders in AS outcomes and management.

Methods

We included 2429 patients (51.5% men; 49.5% women) with severe AS. Median follow-up was 42.0 (21–78) months.

Results

Women were older (p<0.001), more often symptomatic (p=0.007), and presented with smaller aortic valve area (p<0.001), and greater ejection fraction (p<0.001) than men. Despite that women have a longer life expectancy than men in the general population, estimated five-year survival of patients with severe AS was lower for women compared to men (62±2% versus 69±1% respectively, p<0.001). The 5-year survival was lower compared to expected survival, especially for women (62±2% vs. 71% for women and 69±1% vs. 71% for men). The cumulative 5-years incidence of AVR was 79±2% for men, and only 70±2% for women (p<0.001) and, being male was independently predictive of AVR (OR: 1.49 [1.18–1.97]; p=0.011). After propensity matching, when both genders were comparable in terms of characteristics and management (AVR), women, as expected due to their higher life expectancy than men, had better 5-year survival than men (69±2% vs. 62±2%; p=0.023).

Conclusion

Women with severe AS present at a more advance stage of the disease, at older ages with more symptoms, and incur higher mortality than men. This excess mortality is related to a combination of late diagnosis and a less frequent and later referral for AVR than in men. This justifies appropriate measures to improve the situation and to ensure that both sexes receive equivalent care.

Figure 1. (A) Survival curves. (B) Surgery incidence.

Funding Acknowledgement

Type of funding source: None

P3696Correlates of the ratio of acceleration time to ejection time in patients with aortic stenosis: an echocardiographic and computed tomography study

Background

Acceleration time to ejection time ratio (AT/ET) prolongation is associated with increased mortality in patients with aortic stenosis (AS).

Purpose

To identify the determinants associated with increased AT/ET.

Methods

The relationships between AT/ET ratio, clinical and Doppler echocardiographic variables of interest in the setting of AS were studied in 1107 patients with AS and preserved left ventricular (LV) ejection fraction (EF), with Computed Tomography – Aortic Valve Calcium (CT-AVC) score studied in a subgroup of 342 patients.

Results

In univariate analysis, AT/ET ratio did correlate with aortic peak velocity (Vmax, r=0.57, p<0.0001), mean pressure gradient (MPG, r=0.60, p<0.0001), aortic valve area (AVA, r=−0.50, p<0.0001) and CT-AVC score (r=0.24, p<0.0001). An AT/ET ratio had a good accuracy to predict an aortic peak velocity ≥4 m/s, a MPG≥40 mmHg, or an AVA≤1.0 cm2, with an optimal cut-off value of 0.34. By multivariate linear regression analysis, presence of AS-related symptoms, decreased LV stroke volume index, LVEF, systolic blood pressure (SBP), absence of diabetes mellitus, and increased LV mass index, relative wall thickness, and Vmax were independently associated with increased AT/ET ratio (all P<0.05). In the subgroup of patients who underwent CT-AVC, CT-AVC score was independently associated with increased AT/ET ratio (P<0.05).

Conclusion

AT/ET ratio is related to echocardiographic and CT-AVC indices of AS severity. However, multiple intricate factors beyond hemodynamic and anatomic severity of AS influence AT/ET ratio including LV geometry, function and SBP. These findings should be considered when assessing AT/ET in patients with AS and preserved LVEF.

Acknowledgement/Funding

Local funding

P908Prognostic value of energy loss index in patients with low gradient severe aortic stenosis and preserved ejection fraction

Background

Assessment of pressure recovery adjusted indexed aortic valve area (AVAi) – energy loss index (ELI) – has been shown of prognostic interest for patients with asymptomatic and/or mild aortic stenosis (AS), but limited data are available in the setting of low gradient aortic stenosis (LG-AS).

Purpose

We hypothesized that among these patients with LG-AS, reclassification of AS severity as moderate by ELI may help to identify a subgroup of patients with moderate AS.

Methods

379 patients with low gradient severe AS (defined by AVAi ≤0.6 cm2/m2 and mean aortic pressure gradient (MPG) <40 mmHg) and preserved left ventricular ejection fraction (LVEF ≥50%) were prospectively included. Reclassification as moderate AS by ELI was defined as AVAi ≤0.6 cm2 /m2 but an ELI >0.6 cm2/m2. Clinical and echocardiographic features of patients reclassified by ELI were studied. Clinical outcomes were all-cause and cardiac mortality.

Results

148 patients (39%) were reclassified as moderate AS by ELI. By multivariable logistic regression analysis, patients being reclassified as moderate AS by ELI were associated with increased stroke volume index (SVi), absence of documented coronary artery disease and decreased body surface area, left indexed ventricular mass (all p<0.05). During a median follow-up of 34 months (30–38 months), 119 patients died, 52 of them from cardiac causes. Three-year survival free from all-cause or cardiac death were 76±4%, 96±2% for patients with moderate AS by ELI and 71±3%, 84±3% for patients with severe AS by ELI (p=0.178 and p=0.013, respectively). After adjustment for variables of prognostic interest including aortic valve replacement as a time-dependent covariable, there was a significant reduction of risk of cardiac mortality in patients with moderate AS by ELI (adjusted HR 0.44 [95% CI, 0.23–0.85]; p=0.014) but not for all-cause mortality (adjusted HR 0.85 [95% CI, 0.58–1.25]; p=0.403)

Conclusion

In patients with low gradient “severe” AS and preserved ejection fraction, calculation of ELI permits to reclassify almost 40% of patients as having moderate AS. Patients reclassified as moderate AS by ELI had a reduction of risk of cardiac mortality during follow-up but not for all-cause mortality. Calculation of ELI may be useful for decision making in AS patients with discordant grading and preserved ejection fraction.

Acknowledgement/Funding

Local funding

Pharmacogenetic prediction of clinical outcome in advanced colorectal cancer patients receiving 5-fluorouracil (FU)/oxaliplatin (OX) as first-line chemotherapy

2509

Background: Chemotherapy using oxaliplatin, 5-fluorouracil is known to be effective in the treatment of CRC patients. Optimization of this therapy is complicated due to wide variability in drug response that may be due to functional genomic polymorphisms in genes related to the drug target, to the metabolizing or to the DNA repair. We report the evaluation of polymorphisms in the TS, MTHFR (drug target) ERCC1, XPD and GSTP1 (repair enzymes) genes. Methods: We treated 109 CRC patients with a first line oxaliplatin/5-FU chemotherapeutic regimen. Genetic polymorphisms were determined by PCR based RFLP or by Real-Time PCR on an ABI PRISM 7000, using DNA from peripheral blood. The investigated polymorphisms were: TS (VNTR in the 5’ UTR, the 3R G>C SNP and the 1494del6), ERCC1 (Asn118Asn, 8092C>A, 19716 G>C), GSTP1 (Ile105Val) and XPD (Lys751Gln). Clinical response (CR), progression free survival (PFS) and overall survival (OS) were evaluated according to each genotype. Results: The patients were classified according to the clinical risk assessment (CRA) defined by EORTC in three groups with different DFS (12, 9, 7 months; P= 0.008) and different OS (41,19,11 months; P= 0.0002). In the univariate analysis for CR, ERCC1 and XPD polymorphisms were significant (P=0.03, P= 0.047, respectively). After adjustment for the mentioned clinical risk assessment, only ERCC1 retained significance (P=0.037; HR: 4.2, C/C vs T/T). In the univariate analysis for PFS, only ERCC1 polymorphism was significant (P=0.034). After adjustment for the clinical risk, this genotype did not retained its significance (P=0.37). Finally, TS, ERCC1 and XPD polymorphisms were significant in the univariate analysis for overall survival, (P=0.032, P=0.003, P=0.016 respectively). Following the adjustement for the clinical risk, all three genotype variables retained significance (P=0.019, P=0.002, P= 0.024, respectively). Conclusions: i) The EORTC risk assessment classification was a very useful predictor of DFS and OS in our group of patients; ii) Germline genetic polymorphism of ERCC1 predicted response to FU/OX in CRC patients and iii) Polymorphisms in the TS, ERCC1 and XPD genes were good predictors of overall survival.

No significant financial relationships to disclose.

Irinotecan pharmacogenetics: The influence of pharmacodynamic genes

3075

Background: Pharmacogenetic determinants of the disposition of the topoisomerase I (TOP1) poison, irinotecan, appear to predict patient (pt) risk of developing severe toxicity, but do not explain all reported cases of toxicity or tumor response to irinotecan treatment. Proteins encoded by the TOP1, ADPRT, TDP1, CDC45L, NFKB1 and XRCC1 genes abate the cytotoxic action of camptothecins in vitro. Methods: Genetic variation in the drug target, TOP1, and downstream effectors may influence pt outcomes to irinotecan therapy. A retrospective haplotype-association study was undertaken to investigate the hypothesis. The association between common haplotypes of the 6 candidate genes and severe adverse events (Grade 3/4 diarrhea, neutropenia) and tumor response (objective response, overall survival) was examined in 107 advanced colorectal cancer pts treated with irinotecan-based regimens. Haplotype tags (htSNPs) were selected from haplotype cladograms of each gene. Patient DNA was typed for htSNPs using pyrosequencing and haplotype identities estimated using PHASE v.0.9. Results: Genotype frequencies were in Hardy-Weinberg equilibrium. TOP1 IVS4+61 was related to neutropenia incidence (GG<AG<AA, p<0.05) and TDP1 IVS12+79 to objective response (TT<TG<GG, p<0.05). TOP1 IVS4+61 AG+GG survived longer (24.9 months) than AA pts (7.8 months; p<0.005) and ADPRT +852 (A284A) CT+TT pts longer than CCs (p<0.05). More pts with the XRCC1 3/3 diplotype (83%) had an objective response to therapy than pts with other diplotypes (30%, p<0.05). There was a trend towards more ADPRT 2/2s (33%) experiencing severe neutropenia than pts with other diplotypes (13%, p=0.08). No genetic variant influenced diarrhea incidence. Conclusions: This is the first pharmacogenetic investigation of irinotecan pharmacodynamic factors. Our results suggest TOP1 and ADPRT variants may alter a patient’s risk of experiencing neutropenia and TOP1, TDP1, ADPRT and XRCC1 variants may influence tumor response to irinotecan-based therapies.

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Frequent severe liver iron overload after stem cell transplantation and its possible association with invasive aspergillosis

Iron overload is associated with free radical generation and tissue damage. Our main objective was to ascertain the frequency and severity of iron overload in a group of 59 patients who died after conventional-intensity autologous (n=24) or allogeneic (n=35) haematopoietic stem cell transplantation (HSCT). A second objective was to investigate associations between liver-iron concentration and causes of transplant-related mortality. The median age was 41 years (range, 19-66), 41 were males and 18 females. In total, 26 patients had acute leukaemia or MDS, 10 CML, 17 lymphoma, four myeloma and two aplastic anaemia. The median hepatic iron concentration (HIC) was 138 micromol/g dry weight (7.7 mg/g; range 31-631 micromol/g). In total, 4/32 (12%) patients with HIC <150 micromol/g and 10/27 (37%) with hepatic iron > or =150 micromol/g showed invasive aspergillosis at autopsy (P=0.035). This was significant in multivariate analysis (RR 9.0; 95% CI 1.6-50.3, P=0.012). In conclusion, severe iron overload is frequent in patients who die following HSCT and is associated with invasive aspergillosis.

Measurement of liver iron overload by magnetic induction using a planar gradiometer: preliminary human results

The measurement of hepatic iron overload is of particular interest in cases of hereditary hemochromatosis or in patients subject to periodic blood transfusion. The measurement of plasma ferritin provides an indirect estimate but the usefulness of this method is limited by many common clinical conditions (inflammation, infection, etc). Liver biopsy provides the most quantitative direct measurement of iron content in the liver but the risk of the procedure limits its acceptability. This work studies the feasibility of a magnetic induction (MI) low-cost system to measure liver iron overload. The excitation magnetic field (B0, frequency: 28 kHz) was produced by a coil, the perturbation produced by the object (deltaB) was detected using a planar gradiometer. We measured ten patients and seven volunteers in supine and prone positions. Each subject was moved in a plane parallel to the gradiometer several times to estimate measurement repeatability. The real and imaginary parts of deltaB/B0 were measured. Plastic tanks filled with water, saline and ferric solutions were measured for calibration purposes. We used a finite element model to evaluate the experimental results. To estimate the iron content we used the ratio between the maximum values for real and imaginary parts of deltaB/B0 and the area formed by the Nyquist plot divided by the maximum imaginary part. Measurements in humans showed that the contribution of the permittivity is stronger than the contribution of the permeability produced by iron stores in the liver. Defined iron estimators show a limited correlation with expected iron content in patients (R < or = 0.56). A more precise control of geometry and position of the subjects and measurements at multiple frequencies would improve the method.

Patients with biochemical iron overload: causes and characteristics of a cohort of 150 cases

Biochemical iron overload (IO) is a frequent metabolic abnormality. It may be caused by several diseases, and data regarding the relative frequency of these are scant. A single diagnostic protocol including clinical, biochemical, and genetic data was used to diagnose the cause of biochemical IO in a group of 150 patients referred by general practitioners. Severe alterations of the HFE gene (42 patients, 28%), hepatitis C virus infection (33 patients, 22%), and dysmetabolic syndrome with iron overload (DSIO) (22 patients, 15%) emerged as the main causes, and other single causes were found in 20 patients (13%). In 19 patients (13%), multiple causes of IO were found, and in 14 patients no cause was found, 5 of whom had classical criteria of genetic hemochromatosis (GH) without HFE mutations. Transferrin saturation index (TSI) had a very low positive predictive value (0.16) for GH among patients with biochemical IO in this setting. In conclusion, 90% of patients with biochemical IO were diagnosed with a specific disorder. GH, hepatitis C infection, and DSIO were the major causes, and a large group of patients had multiple causes of IO. TSI is not a useful indicator of GH in patients referred by general practitioners.