Low-gradient Stenosis Research Articles

A clinical case of transapical aortic valve implantation for low-gradient stenosis in a comorbid patient with COVID-19-associated pneumonia

Aortic stenosis is the leading entity in the structure of valvular pathology in adult population with the frequency ranging from 2 to 4% in the general population. The distinct features of this defect include slow progression and frequent lack of correlation between the severity of stenosis according to clinical and instrumental data. The article presents the case of successful transcatheter aortic valve implantation by transapical access in a 71-year-old patient with symptomatic low-flow, low-gradient aortic stenosis, heart failure with preserved left ventricular ejection fraction, a history of coronary artery bypass grafting, severe concomitant pathology, and recent moderate COVID-19 coronavirus infection. The complexity of management of elderly patients with combined pathology is updated, and a multidisciplinary approach to clinical decision-making in a high-risk clinical situation is demonstrated.

P1303 Pseudo-severe aortic stenosis due to mechanical dyssynchrony in a patient with low contractile reserve

Abstract Introduction Aortic stenosis characterization in patients with low flow – low gradient stenosis (LF-LG) and reduced left ventricular (LV) ejection fraction (EF) is challenging. In this subgroup, pseudo- severe stenosis should be properly identified, as these patients are treated conservatively with heart failure therapy. Its identification relies mainly on preserved contractile reserve seen during dobutamine echocardiography. We present a patient with low contractile reserve and pseudo-severe stenosis due to mechanical dyssynchrony. Case presentation 83-years old patient with ischemic heart disease and chronic kidney disease was admitted to our department due to progressive exertional dyspnea. In 2014 he underwent dual-chamber pacemaker (PM) implantation due to sick sinus syndrome and was programmed to asynchronous pacing mode (VVI mode) in 2016 as atrial electrode dysfunction was observed. Coronary angiogram was normal. Echocardiography showed enlarged left ventricle (LV EDV 180 ml), reduced EF (33%) and signs of mechanical dyssynchrony. Peak aortic valve velocity was 2.5 m/s, mean pressure gradient (MPG) 13 mmHg and AVA 1.0 cm2. Stroke volume was reduced (SVI 28 ml/m2). LF-LG aortic stenosis was suspected. Stress echocardiography using dobutamine at peak infusion of 15 mcg/kg/min showed low contractile reserve (EF 37%, SVI 33 ml/m2) with no significant changes in aortic valve parameters (MPG 29 mmHg, AVA 0.9 cm2). However, significant masurement disparity was noted and at least partly contributed to atrio-ventricular (A-V) and inter-ventricular dyssynchrony because of asynchronous VVI pacing. To overcome A-V and intraventricular dyssynchrony we decided for atrial lead reposition and upgrade to cardiac resynchronization therapy (CRT-P). After six months of CRT, normalization of EF and improvement of exercise capacity were observed. Furthermore, additional evaluation of aortic valve showed only moderate stenosis (peak velocity 2,8 m/s, MPG 18 mmHg and AVA 1.4 cm2). Stroke volume was normal (SVI 48 ml/m2). Consequently, we postponed potential surgical or interventional treatment of the aortic valve. Conclusion Considerable LV mechanical dyssynchrony could interfere with determining the severity of aortic stenosis. As demonstrated in the present case report, special considerations should be taken in patients with notable LV dyssynchrony and low contractile reserve as it may not be overcome with dobutamine stress echocardiography as recommended by the current guidelines.

P928Pseudo-discordance mimicking low-flow low-gradient AS in TAVR patients with severe symptomatic aortic stenosis

Abstract Background The combination of a small aortic valve area valve area (AVA) and a low mean gradient (MG) severity pose a serious clinical challenge in the diagnosis of severe aortic stenosis (AS). While this discordance is frequently labeled “low-flow low-gradient AS”, there are two additional potential causes: underestimation of MG and underestimation of AVA. Purpose To investigate prevalence and root causes of discordant echocardiographic findings in symptomatic patients with AS and normal LV function by comparing Doppler data, invasive hemodynamic data, CT LV outflow tract size and calcium score. Methods and results We studied 67 severely symptomatic patients with AS and an LVEF>50%. Thirty patients (45%) had discordant echocardiographic findings (MG<40 mmHg, AVA≤1cm2). Of those, 16 had also discordant findings by invasive measurements (True Discordants), compatible with low-gradient severe AS. In 14, catheterization data were actually concordant and hence discrepant to the echocardiographic findings (False Discordants): In 7 of them, the echocardiographic MG was >35 mmHg; in 5 it was >30 mmHg and only in 2 between 25 and 29 mmHg. In 6 of the 14 patients with underestimated MG, no right parasternal Doppler examination had been performed, LVOT VTI tracings were clearly suboptimal in 3 patients and 1 case was deemed inadequate due to poor imaging quality. LVOT area by echocardiography or by CT could not differentiate between Concordants and Discordants (p=0.3 and p=0.8 respectively) or between True and False Discordants (p=0.5 and p=0.6 respectively). While calcium score was similar in Concordants (2711±1159 AU) and False Discordants (2692±1136AU, p=0.96), it tended to be higher in Concordants (2711±1159 AU), when compared to True Discordants (1906±1284 AU, p=0.07). In patients with concordant echocardiographic findings calcium score levels of >3000 AU in men and >1600 AU in female had a positive predictive value (PPV) of 90% for the correct diagnosis of severe aortic stenosis. In patients with discordant findings the PPV was 80%. Conclusions 1) The majority of severely symptomatic AS patients with normal LV systolic function an echocardiographic AVA≤1.0 cm2 and a MG>30mmHg considered for TAVR have severe AS by calcium score. 2) In this patient population, discordant echocardiographic findings are in about half of the cases due to technical factors (“pseudo-discordance”) rather than due to true low flow low-gradient stenosis. 3) Pseudo-discordance is mainly due to mild-moderate underestimation of gradients, caused by a lack of reliable right parasternal tracings, rather than due to underestimation of valve area due to the echocardiographic circularity assumption in the presence of an elliptical LVOT. 4) The diagnosis of true low-flow AS cannot be established without a clear Doppler tracing from the right parasternal window. 5) Absent an adequate right parasternal window, patients should undergo CT assessment of calcium score.

Aortic Stenosis: New Thoughts on a Cardiac Disease of Older People

We have entered a new era in understanding degenerative aortic stenosis in elderly patients. With the aging of the US population and the progressive decrease in coronary heart disease prevalence in the past 50 years, aortic stenosis has become a major cardiac concern. New perspectives of the disease now lead us to see the condition in terms of the response of the left ventricle and of systemic features, rather than just in terms of the valve area itself. A new classification of aortic stenosis recognizes 4 categories based on flow state (normal or low) and valve gradient (high or low). "Paradoxical" low-flow, low-gradient stenosis has a dismal prognosis in spite of a normal left ventricular ejection fraction. New measures of aortic flow and the response of the left ventricle provide new insights into the treatment of patients with this condition.