Insights into the mechanism of paradoxical low-flow, low-pressure gradient severe aortic stenosis: association with reduced O2 consumption by the whole body.

The mechanism of reduced stroke volume index (SVi) in paradoxical low-flow, low-pressure gradient (PLFLPG) aortic stenosis (AS) remains unclarified. Guyton et al. ( 21 ) demonstrated that SVi is determined by whole body O2 consumption (V̇o2) in many subjects, including patients with heart disease. We hypothesized that reduced SVi in PLFLPG AS is associated with reduced V̇o2 by the whole body. This study investigated the relationship between V̇o2, SVi, and AS severity in patients with AS to examine the association between reduced V̇o2 and PLFLPG AS. In 59 patients (24 men and 35 women, mean age: 78 ± 7 yr old) with severe AS, SVi, AS severity, and type were evaluated by echocardiography, and V̇o2 was measured by the fraction of O2 in expired gases. SVi and V̇o2 were significantly decreased in 20 patients with PLFLPG AS compared with 39 patients with non-PLFLPG AS (30 ± 4 vs. 41 ± 7 ml/m2 and 2.4 ± 0.5 vs. 3.0 ± 0.5 ml·min-1·kg-1, respectively, P < 0.01). The SVi-to-V̇o2 ratio was not different between the two groups (13.1 ± 2.6 vs. 13.6 ± 2.1, not significant). SVi was independently correlated with V̇o2 ( r = 0.74, P < 0.01) but not with the aortic valve area index. Categorized PLFLPG AS was also significantly associated with reduced V̇o2 ( P < 0.001). PLFLPG AS is associated with reduced V̇o2 by the whole body, which may offer insights into the mechanism of PLFLPG AS. NEW & NOTEWORTHY Paradoxical low-flow, low-pressure gradient severe aortic stenosis (PLFLPG AS) is an important and problematic subtype, and its central pathophysiology with reduced stroke volume is yet to be clarified. We hypothesized and subsequently clarified that reduced stroke volume in PLFLPG AS is associated with reduced O2 consumption by the whole body. This study suggests important insights into the mechanism of PLFLPG AS and may further promote studies to investigate further mechanisms and novel treatment.

Surgical as Opposed to Transcatheter Aortic Valve Replacement Improves Basal Interventricular Septal Hypertrophy.

BACKGROUND: Basal interventricular septum (IVS) hypertrophy (BSH) with reduced basal IVS contraction and IVS-aorta angle is frequently associated with aortic stenosis (AS). BSH shape suggests compression by the longitudinally elongated ascending aorta, causing basal IVS thickening and contractile dysfunction, further suggesting the possibility of aortic wall shortening to improve the BSH. Surgical aortic valve replacement (SAVR), as opposed to transcatheter AVR (TAVR), includes aortic wall shortening by incision and stitching on the wall and may potentially improve BSH. We hypothesized that BSH configuration and its contraction improves after SAVR in patients with AS. Methods and Results: In 32 patients with SAVR and 36 with TAVR for AS, regional wall thickness and systolic contraction (longitudinal strain) of 18 left ventricular (LV) segments, and IVS-aorta angle were measured on echocardiography. After SAVR, basal IVS/average LV wall thickness ratio, basal IVS strain, and IVS-aorta angle significantly improved (1.11±0.24 to 1.06±0.17; -6.2±5.7 to -9.1±5.2%; 115±22 to 123±14°, P<0.001, respectively). Contractile improvement in basal IVS was correlated with pre-SAVR BSH (basal IVS/average LV wall thickness ratio or IVS-aorta angle: r=0.47 and 0.49, P<0.01, respectively). In contrast, BSH indices did not improve after TAVR. CONCLUSIONS: In patients with AS, SAVR as opposed to TAVR improves associated BSH and its functional impairment.

[Echocardiography and Biochemical Examination in the Treatment of Ischemic Heart Disease].

The importance of echocardiography is generally known for acute coronary syndrome. However, assessing cardiac biomarker elevation is important together with echocardiography as poor images are obtained in some cases and patients may show unstable angina or angina on effort without asynergy. We examined the usefulness of high sensitive troponin I (hs-cTnI) in 60 patients from October 2014. We performed hs-cTnI and echocardiography in 10 cases (acute myocardial infarction: 8, unstable angina: 1, angina on effort: 1) among those patients. In the 8 acute myocardial infarction cases, asynergy was noted in all cases on echocardiography, but CK, CK-MB, and H-FABP cardiac biomarkers showed mixed negativity and positivity. Also, the unstable angina and angina on effort did not show asynergy but hs-cTnI was positive, the case of unstable angina showed elevation over time, but the case of angina on effort did not show elevation with time. We suggest that echocardiography and hs-cTnI are useful for acute myocardial infarction, although care may be necessary when assessing ACS patients with no detected asynergy in echocardiographs or non-ACS patients with acutely elevated hs-cTnI). In addition, it was suggested that confirmation of a change over time of hs-cTnI is necessary in angina patients.