Severe aortic stenosis without left ventricular hypertrophy: prevalence, predictors, and short-term follow up after aortic valve replacement

Cardiac magnetic resonance patterns of left ventricular remodeling in patients with severe aortic stenosis referred to surgical aortic valve replacement

Left ventricular (LV) hypertrophy is a common finding in patients with severe aortic stenosis (AS). Cardiac magnetic resonance (CMR) is the gold-standard technique to evaluate LV remodeling. Our aim was to assess the prevalence and describe the patterns of LV adaptation in AS patients before and after surgical aortic valve replacement (AVR). Prospective study of 130 consecutive patients (71y [IQR 68-77y], 48% men) with severe AS, referred for surgical AVR. Patterns of LV remodeling were assessed by CMR. Besides normal LV ventricular structure, four other patterns were considered: concentric remodeling, concentric hypertrophy, eccentric hypertrophy, and adverse remodeling. At baseline CMR study: mean LV indexed mass: 81.8 ± 26.7 g/m2; mean end-diastolic LV indexed volume: 85.7 ± 23.1 mL/m2 and median geometric remodeling ratio: 0.96 g/mL [IQR 0.82-1.08 g/mL]. LV hypertrophy occurred in 49% of subjects (concentric 44%; eccentric 5%). Both normal LV structure and concentric remodeling had a prevalence of 25% among the cohort; one patient had an adverse remodeling pattern. Asymmetric LV wall thickening was present in 55% of the patients, with predominant septal involvement. AVR was performed in 119 patients. At 3-6 months after AVR, LV remodeling changed to: normal ventricular geometry in 60%, concentric remodeling in 27%, concentric hypertrophy in 10%, eccentric hypertrophy in 3% and adverse remodeling (one patient). Indexes of AS severity, LV systolic and diastolic function and NT-proBNP were significantly different among the distinct patterns of remodeling. Several distinct patterns of LV remodelling beyond concentric hypertrophy occur in patients with classical severe AS. Asymmetric hypertrophy is a common finding and LV response after AVR is diverse.

Strain Assessment in Aortic Stenosis: Pathophysiology and Clinical Utility

Contemporary echocardiographic criteria for grading aortic stenosis severity have remained relatively unchanged, despite significant advances in noninvasive imaging techniques over the last 2 decades. More recently, attention has shifted to the ventricular response to aortic stenosis and how this might be quantified. Global longitudinal strain, semiautomatically calculated from standard two-dimensional echocardiographic images, has been the focus of extensive research. Global longitudinal strain is a sensitive marker of subtle hypertrophy-related impairment in left ventricular function and has shown promise as a relatively robust prognostic marker, both independently and when added to severity classification systems. Herein we review the pathophysiological basis underpinning the potential utility of global longitudinal strain in the assessment of aortic stenosis, as well as its potential role in quantifying myocardial recovery and prognostic discrimination following aortic valve replacement.

Left ventricular mass regression after aortic valve replacement with the TTK Chitra™ monoleaflet tilting disc valve

Objective

To study the extent of left ventricular (LV) mass regression in aortic stenosis after aortic valve replacement with the TTK Chitra™ tilting disc valve.

Methods and materials

This study included patients with severe isolated aortic stenosis (AS), admitted in our department. They had aortic valve replacement (AVR) with the TTK Chitra™ tilting disc valve, between January 2008 and December 2010. Data were collected from consecutive forty-eight patients. LV mass and diametric and functional parameters were recorded preoperatively and compared with echocardiography after 3 months, 6 months, then yearly, up to 3 years.

Results

70.8% of the patients were males and 29.2% were females. The mean duration of illness was 37.92 ± 25.87 months. The mean LV ejection fraction increased 3 months after surgery (61.56 ± 10.10% to 69.31 ± 9.34%) with a sustained increase for the next 3 years. The mean LV end-diastolic diameter decreased (50.16 ± 6.05 mm to 45.69 ± 5.93 mm) after 3 months of surgery, with a sustained decrease for the next 3 years. The mean LV end-systolic diameter decreased (32.84 ± 6.96 mm to 29.41 ± 5.86 mm) after 3 months of surgery and then showed a sustained decrease for the next 3 years. The LV mass assessed with echocardiography regressed from 324.65 ± 97.77 g before surgery to 252.64 ± 71.12 g after 3 months and then showed a sustained decrease over the next 3 years.

Conclusion

Significant LV mass regression occurred after AVR with the TTK Chitra™ valve. The maximum reversal was found to be within the first 3 months after surgery with sustained beneficial improvement for the next 3 years.

Echocardiographic Global Longitudinal Strain Is Associated With Myocardial Fibrosis and Predicts Outcomes in Aortic Stenosis

Aims: Left ventricular ejection fraction is the conventional measure used to guide heart failure management, regardless of underlying etiology. Left ventricular global longitudinal strain (LV-GLS) by speckle tracking echocardiography (STE) is a more sensitive measure of intrinsic myocardial function. We aim to establish LV-GLS as a marker of replacement myocardial fibrosis on cardiovascular magnetic resonance (CMR) and validate the prognostic value of LV-GLS thresholds associated with fibrosis.

Methods and results: LV-GLS thresholds of replacement fibrosis were established in the derivation cohort: 151 patients (57 ± 10 years; 58% males) with hypertension who underwent STE to measure LV-GLS and CMR. Prognostic value of the thresholds was validated in a separate outcome cohort: 261 patients with moderate-severe aortic stenosis (AS; 71 ± 12 years; 58% males; NYHA functional class I–II) and preserved LVEF ≥50%. Primary outcome was a composite of cardiovascular mortality, heart failure hospitalization, and myocardial infarction. In the derivation cohort, LV-GLS demonstrated good discrimination (c-statistics 0.74 [0.66–0.83]; P < 0.001) and calibration (Hosmer-Lemeshow χ² = 6.37; P = 0.605) for replacement fibrosis. In the outcome cohort, 47 events occurred over 16 [3.3, 42.2] months. Patients with LV-GLS > −15.0% (corresponding to 95% specificity to rule-in myocardial fibrosis) had the worst outcomes compared to patients with LV-GLS < −21.0% (corresponding to 95% sensitivity to rule-out myocardial fibrosis) and those between −21.0 and −15.0% (log-rank P < 0.001). LV-GLS offered independent prognostic value over clinical variables, AS severity and echocardiographic LV mass and E/e′.

Conclusion: LV-GLS thresholds associated with replacement myocardial fibrosis is a novel approach to risk-stratify patients with AS and preserved LVEF.

Small Left Ventricle and Clinical Outcomes After Transcatheter Aortic Valve Replacement

Background

In patients undergoing transcatheter aortic valve replacement (TAVR), those with small left ventricle (LV) may have an increased risk of poor outcomes, because small LV is associated with low‐flow (LF), left ventricular hypertrophy. However, the impact of small LV on patients undergoing TAVR remains unknown.

Methods and Results

We examined 2584 patients who underwent TAVR between October 2013 and May 2017 using data from the Japanese multicenter registry. On the basis of the American Society of Echocardiography guidelines, small LV was defined as left ventricular end‐diastolic dimension <42.0 mm for men or <37.8 mm for women. The 2‐year clinical outcomes were compared between patients with and without small LV using multivariable Cox regression analyses and propensity score matching. Subgroup analyses by LF, left ventricular hypertrophy were performed. Of 2584 patients who underwent TAVR, 466 (18.0%) had small LV. Patients with small LV had smaller body size and less comorbidity, and were more likely to have LF status compared with those without. Small LV was associated with a higher 2‐year all‐cause (20.8% versus 14.3%; adjusted hazard ratio [HR],1.58 [95% CI, 1.20–2.09]; P=0.0013) and cardiovascular mortality (8.8% versus 5.5%; adjusted HR, 1.93 [95% CI, 1.25–2.98]; P=0.0028). Propensity score matching analysis showed consistent findings. In subgroup analyses, LF, left ventricular hypertrophy did not interact with small LV.

Conclusions

Small LV, determined by a simple echocardiographic parameter, was associated with poorer clinical outcomes after TAVR regardless of LF, left ventricular hypertrophy. LV size may be useful for assessing clinical outcomes after TAVR.

Registration

URL: https://www.umin.ac.jp/ctr/index.htm; Unique identifier: UMIN000020423.

Left Ventricular Remodeling in Degenerative Aortic Valve Stenosis

Aortic stenosis was once considered a pure isolated valve obstacle challenging left ventricle driving force of contraction and flow generation. Left ventricular (LV) adaptation was merely interpreted as a uniform hypertrophic response to increased afterload. However, in these last 2 decades cardiac imaging research and some histopathology correlation studies brought insight towards the complex interaction between the vasculature, the valve and the myocardium. Verily, LV remodeling in this setting is a complex multidetermined process that goes further beyond myocardial hypertrophy. Ultrastructural changes involving both diffuse and replacement fibrosis of the myocardium take part and might explain the transition of clinical phenotypes with distinct prognosis, from compensated hypertrophy to LV maladaptive dysfunction and heart failure. Presently, the combined appropriate use of echocardiography and cardiac magnetic resonance may better assess the global LV afterload, hypertrophy and geometric remodeling, global and regional LV function, beyond ejection fraction, and structural changes that include the fibrotic burden of the myocardium. As a whole these may not only better stratify individual risk of disease progression but also identify patients benefiting from earlier valve intervention. In this paper, we review the maladaptive response of the LV to chronic pressure overload, describing the different signaling pathways and mechanisms that underly both hypertrophy and remodeling. Histomorphology changes in this setting are described and we try to make sense of the use of new imaging tools for LV characterization.

Prognostic effect of increased left ventricular wall thickness in severe aortic stenosis

Background

It is unclear whether increased left ventricular (LV) thickness is associated with worse clinical outcomes in severe aortic stenosis (AS). The aim of this study was to determine the effect of increased LV wall thickness (LVWT) on major clinical outcomes in patients with severe AS.

Methods and results

This study included 290 severe AS patients (mean age 69.4 ± 11.0 years; 136 females) between January 2008 and December 2018. For outcome assessment, the endpoint was defined as death from all causes, cardiovascular death, and the aortic valve replacement (AVR) surgery rate. During follow-up (48.7 ± 39.0 months), 157 patients had AVR, 43 patients died, and 28 patients died from cardiovascular causes. Patients with increased LVWT underwent AVR surgery much more than those without LVWT (60.0% vs. 39.0%, p < 0.001). Furthermore, in patients with increased LVWT, the all-cause and cardiovascular death rates were significantly lower in the AVR group than in the non-AVR group (8.8% vs. 27.3%, p < 0.001, 4.8%, vs. 21.0%, p < 0.001). Multivariate analysis revealed that increased LVWT, age, dyspnea, and AVR surgery were significantly correlated with cardiovascular death.

Conclusions

In patients with severe AS, increased LVWT was associated with a higher AVR surgery rate and an increased rate of cardiovascular death independent of other well-known prognostic variates. Thus, these findings suggest that increased LVWT might be used as a potential prognostic factor in severe AS patients.

"Pure" severe aortic stenosis without concomitant valvular heart diseases: echocardiographic and pathophysiological features

Purpose

In echocardiography the severity of aortic stenosis (AS) is defined by effective orifice area (EOA), mean pressure gradient (mPG_AV) and transvalvular flow velocity (maxV_AV). The hypothesis of the present study was to confirm the pathophysiological presence of combined left ventricular hypertrophy (LVH), diastolic dysfunction (DD) and pulmonary artery hypertension (PAH) in patients with “pure” severe AS.

Methods and Results

Patients (n = 306) with asymptomatic (n = 133) and symptomatic (n = 173) “pure” severe AS (mean age 78 ± 9.5 years) defined by indexed EOA < 0.6 cm² were enrolled between 2014 and 2016. AS patients were divided into 4 subgroups according to mPG_AV and indexed left ventricular stroke volume: low flow (LF) low gradient (LG)-AS (n = 133), normal flow (NF) LG-AS (n = 91), LF high gradient (HG)-AS (n = 21) and NFHG-AS (n = 61). Patients with “pure” severe AS showed mean mPG_AV of 31.7 ± 9.1 mmHg and mean maxV_AV of 3.8 ± 0.6 m/s. Only 131 of 306 patients (43%) exhibited mPG_AV > 40 mmHg and maxV_AV > 4 m/s documenting incongruencies of the AS severity assessment by Doppler echocardiography. LVH was documented in 81%, DD in 76% and PAH in 80% of AS patients. 54% of “pure” AS patients exhibited all three alterations. Ranges of mPG_AV and maxV_AV were higher in patients with all three alterations compared to patients with less than three. 224 (73%) patients presented LG-conditions and 82 (27%) HG-conditions. LVH was predominant in NF-AS (p = 0.014) and PAH in LFHG-AS (p = 0.014). Patients’ treatment was retrospectively assessed (surgery: n = 100, TAVI: n = 48, optimal medical treatment: n = 156).

Conclusion

In patients with “pure” AS according to current guidelines the presence of combined LVH, DD and PAH as accepted pathophysiological sequelae of severe AS cannot be confirmed. Probably, the detection of these secondary cardiac alterations might improve the diagnostic algorithm to avoid overestimation of AS severity.

Sex differences in aortic stenosis: from pathophysiology to treatment

Introduction: In aortic stenosis (AS), there are clear sex differences in clinical presentation, left ventricular (LV) response to pressure overload, and pathophysiology of valvular calcification. These differences may affect outcome following valve intervention.Area covered: This review aims to discuss sex differences in clinical presentation, pathophysiology of aortic valve calcification, LV remodeling in view of historic and recent echocardiographic and cardiac magnetic resonance imaging studies, and outcome after valve intervention. In addition, it will also provide some brief insights on the exercise physiology in women and men with AS.Expert commentary: Women at presentation are often older, have higher prevalence of hypertension and diastolic dysfunction, while men are younger, and more often have a bicuspid aortic valve and higher atherosclerotic disease burden. Men have more valve calcification than women for a given severity of AS and develop different patterns of LV remodeling and myocardial fibrosis. Although women tend to walk shorter on treadmill and achieve lower metabolic equivalents, they achieve similar peak heart rates and blood pressure, and the frequency of revealed symptoms during exercise test is comparable in both sexes. Men are more likely to undergo a surgical AVR with better outcome, while women have generally better outcome after TAVI.

Low and elevated B-type natriuretic peptide levels are associated with increased mortality in patients with preserved ejection fraction undergoing transcatheter aortic valve replacement: an analysis of the PARTNER II trial and registry

Aims

B-type natriuretic peptide (BNP) is a cardiac neurohormone that is secreted in response to ventricular volume expansion and pressure overload. There are conflicting data regarding the association between BNP levels and outcomes after transcatheter aortic valve replacement (TAVR). We therefore sought to assess the association between baseline BNP and adverse outcomes in patients with symptomatic, severe aortic stenosis (AS), and left ventricular ejection fraction (LVEF) ≥50%, undergoing TAVR in the PARTNER 2 Trial and Registry.

Methods and results

A total of 1782 patients were included in the analysis, and BNP was evaluated both as a continuous log-transformed value and by a priori categories: low (&lt;50 pg/mL), normal (≥50 and &lt;100 pg/mL), moderately elevated (≥100 and &lt;400 pg/mL), or markedly elevated (≥400 pg/mL). Clinical outcomes from discharge to 2 years were compared between patients according to their baseline BNP level, using Kaplan–Meier event rates and multivariable Cox proportional hazards regression models. After adjustment, spline curves revealed a non-linear association between log-transformed BNP and all-cause and cardiovascular mortality in which both the lowest and highest values were associated with increased mortality. Two-year all-cause mortality rates for those with low (n = 86), normal (n = 202), moderately elevated (n = 885), and markedly elevated (n = 609) baseline BNP were 20.0%, 9.8%, 17.7%, and 26.1%, respectively. In adjusted models, compared to a normal baseline BNP, low [adjusted hazard ratio (HR) 2.6, 95% confidence interval (CI) 1.3–5.0, P-value 0.005], moderately elevated (adjusted HR 1.6, 95% CI 1.0–2.6, P-value 0.06), and markedly elevated (adjusted HR 2.1, 95% CI 1.3–3.5, P-value 0.003) BNP were associated with increased all-cause mortality, driven by cardiovascular mortality.

Conclusions

In a large cohort of patients with severe symptomatic AS and preserved LVEF undergoing TAVR, all-cause and cardiovascular mortality rates at 2 years were higher in patients with low and markedly elevated BNP levels.

Clinical Trial Registration

https://clinicaltrials.gov/ unique identifier #NCT01314313, #NCT02184442, #NCT03222128, and #NCT03222141.

Better Myocardial Function in Aortic Stenosis with Low Left Ventricular Mass: A Mechanism of Protection against Heart Failure Regardless of Stenosis Severity?

About one-tenth to one-third of patients with severe aortic stenosis (AS) do not develop left ventricular hypertrophy (LVH). Intriguingly, the absence of LVH despite severe AS is associated with lower prevalence of heart failure (HF), which challenges the classical notion of LVH as a beneficial compensatory response. Notably, the few studies that have attempted to characterize AS subjects with inadequately low left ventricular (LV) mass relative to LV afterload (i-lowLVM) described better prognosis and enhanced LV performance in AS associated with i-lowLVM, but those reports were limited to severe AS. Our aim was to compare myocardial function between moderate and severe AS with i-lowLVM. We retrospectively analyzed in-hospital records of 225 clinically stable nondiabetic patients with isolated moderate or severe degenerative AS in sinus rhythm, free of coexistent diseases. Subjects with i-lowLVM were compared to those with appropriate or excessive LVM (a/e-LVM), defined on the basis of the ratio of a measured LVM to the LVM predicted from an individual hemodynamic load. Patients with i-lowLVM and a/e-LVM did not differ in aortic valve area, LV end-diastolic diameter (LVd, a measure of LV preload), and circumferential end-systolic LV wall stress (cESS), an estimate of LV afterload. Compared to a/e-LVM, patients with i-lowLVM had increased LV ejection fraction (EF) and especially higher LV midwall fractional shortening (a better index of LV myocardial function than EF in concentric LV geometry) (p < 0.001–0.01), in both moderate and severe AS. LVd and cESS were similar in the four subgroups of the study subjects, i.e., moderate AS with i-lowLVM, moderate AS with a/e-LVM, severe AS with i-lowLVM, and severe AS with a/e-LVM (p > 0.6). Among patients with i-lowLVM, LVM did not differ significantly between moderate and severe AS (p > 0.4), while in those with a/e-LVM, LVM was increased in severe versus moderate AS (p < 0.001). In conclusion, the association of the low-LVM phenotype with better myocardial contractility may already develop in moderate AS. Additionally, cESS appears to be a controlled variable, which is kept constant over AS progression irrespective of LVM category, but even when controlled (by increasing LVM), is not able to prevent deterioration of LV function. Whether improved myocardial performance contributes to favorable prognosis and the preventive effect against HF in AS without LVH, remains to be studied.

Pathophysiological coronary and microcirculatory flow alterations in aortic stenosis

Regulation of coronary blood flow is maintained through a delicate balance of ventriculoarterial and neurohumoral mechanisms. The aortic valve is integral to the functions of these systems, and disease states that compromise aortic valve integrity have the potential to seriously disrupt coronary blood flow. Aortic stenosis (AS) is the most common cause of valvular heart disease requiring medical intervention, and the prevalence and associated socio-economic burden of AS are set to increase with population ageing. Valvular stenosis precipitates a cascade of structural, microcirculatory, and neurohumoral changes, which all lead to impairment of coronary flow reserve and myocardial ischaemia even in the absence of notable coronary stenosis. Coronary physiology can potentially be normalized through interventions that relieve severe AS, but normality is often not immediately achievable and probably requires continued adaptation. Finally, the physiological assessment of coronary artery disease in patients with AS represents an ongoing challenge, as the invasive physiological measures used in current cardiology practice are yet to be validated in this population. This Review discusses the key concepts of coronary pathophysiology in patients with AS through presentation of contemporary basic science and data from animal and human studies.

Remodeling classification system considering left ventricular volume in patients with aortic valve stenosis: Association with adverse cardiovascular outcomes

BACKGROUND

To assess prevalence and clinical implications of left ventricular (LV) remodeling considering: LV volume, mass and relative wall thickness at the time of aortic valve stenosis diagnosis.

METHODS AND RESULTS

We retrospectively analyzed 343 patients (age 79.2 ± 9.5 years, 48.1% males) with functional aortic valve area (AVA) ≤ 1.5 cm² . LV geometric patterns and clinical outcomes (combined death, cardiac hospitalization, aortic valve replacement [AVR]) were evaluated. According to the new LV remodeling classification, 4.9% had normal geometry, 7.5% concentric remodeling, 39.3% concentric hypertrophy (LVH), 22.4% mixed LVH, 12.5% dilated LVH, 3.2% eccentric LVH and 4.3% eccentric remodeling, 5.5% had not classifiable LVH. Indexed stroke volume (SVi) was higher in patients with concentric LVH (40.3 ± 11.9 mL/m² ) and mixed LVH (41.6 ± 13.4 mL/m² ) and lower in patients with eccentric LVH (24.9 ± 7.7 mL/m² ), concentric (36.6 ± 12.7 mL/m² ) and eccentric remodeling (34.9 ± 9.5 mL/m² ), P = 0.003. During a median follow-up of 2.2 years, 260 (75.8%) had the combined end point. A significant association between the combined end point and LV dilation (P = 0.010) or LV remodeling patterns (P = 0.0001) was found. After multivariable adjustment for AVR, concentric remodeling (HR 3.12, IC 95% 1.14-8.55; P = 0.02) and dilated LVH (HR 3.48, IC 95% 1.31-9.27; P = 0.01) were strongly associated with death or cardiac hospitalizations.

CONCLUSIONS

In patients with AVA ≤ 1.5 cm² , when the new LV remodeling classification system is applied, only a minority had normal geometry and less than half had "classic" concentric LVH or remodeling. LV volume dilatation is frequent and associated with adverse outcome. Concentric remodeling, eccentric remodeling, dilated LVH had the worst noninvasive hemodynamic profile and prognosis.

Association of Inadequately Low Left Ventricular Mass with Enhanced Myocardial Contractility in Severe Degenerative Aortic Stenosis

Background: Left ventricular hypertrophy (LVH), traditionally considered an adaptive mechanism that is aimed at the maintenance of LV systolic function, is absent in 10%–35% of patients with severe aortic stenosis (AS). Our aim was to estimate the clinical and hemodynamic characteristics in patients with severe AS and absent LVH, or inadequately low LV mass (i-lowLVM) relative to an individual hemodynamic load. Methods: We retrospectively analyzed in-hospital records of 100 patients with pure severe degenerative AS, preserved LV systolic function and without relevant coexistent diseases, except for well-controlled hypertension or diabetes. Results: Clinical characteristics were similar in patients with and without LVH, as well as those with and without i-lowLVM, except for slightly lower GFR at i-lowLVM. When compared to their counterparts, subjects without LVH or with i-lowLVM had smaller LV cavities, decreased LV wall thicknesses and higher EF. There were no significant differences in stenosis severity and indices of afterload (valvulo-arterial impedance and circumferential end-systolic LV wall stress), according to the presence or absence of either LVH or i-lowLVM. However, LV fractional shortening at the midwall level was elevated only in patients with i-lowLVM, but not in those without LVH, compared to the remainder (15.8 ± 3.3 vs. 12.9 ± 3.2%, p < 0.001 for those with and without i-lowLVM, respectively; 13.7 ± 3.7 vs. 13.8 ± 3.6% for LVH presence and absence, p = 0.9). Conclusions: Inadequately low LVM relative to the individual hemodynamic load could potentially reflect a different mode of the LV response to severe AS, associated with enhanced load-independent LV systolic performance, i.e., better LV contractility. If confirmed in a large series of patients, our small preliminary study may add to the possible mechanisms of a previously reported counterintuitive tendency of a lower, not higher, risk of adverse outcome in patients with low LV mass despite severe AS. Prospective studies are warranted, in order to determine a potential utility of LVM inadequacy in the risk stratification of patients with AS.

Is left ventricular hypertrophy a friend or foe of patients with aortic stenosis?

Left ventricular hypertrophy (LVH) is traditionally considered a physiological compensatory response to LV pressure overload, such as hypertension and aortic stenosis (AS), in an effort to maintain LV systolic function in the face of an increased afterload. According to the Laplace law, LV wall thickening lowers LV wall stress, which in turn would be helpful to preserve LV systolic performance. However, numerous studies have challenged the notion of LVH as a putative beneficial adaptive mechanism. In fact, the magnitude of LVH is associated with higher cardiovascular morbidity and mortality, especially when LVH is disproportionate to LV afterload. We have briefly reviewed: first, the importance of non-valvular factors, beyond AS severity, for total LV afterload and symptomatic status in AS patients; second, associations of excessive LVH with LV dysfunction and adverse outcome in AS; third, prognostic relevance of the presence or absence of pre-operative LVH in patients referred for aortic valve surgery; fourth, time course, determinants and prognostic implications of LVH regression and LV function recovery after surgical valve replacement and transcatheter aortic valve implantation (TAVI) with a focus on TAVI-specific effects; fifth, the potential of medical therapy to modulate LVH before and after surgical or interventional treatment for severe AS, a condition perceived as a relative contraindication to renin-angiotensin system blockade.

A comprehensive study of calcific aortic stenosis: from rabbit to human samples

The global incidence of calcific aortic stenosis (CAS) is increasing owing, in part, to a growing elderly population. The condition poses a great challenge to public health, because of the multiple comorbidities of these older patients. Using a rabbit model of CAS, we sought to characterize protein alterations associated with calcified valve tissue that can be ultimately measured in plasma as non-invasive biomarkers of CAS. Aortic valves from healthy and mild stenotic rabbits were analyzed by two-dimensional difference gel electrophoresis, and selected reaction monitoring was used to directly measure the differentially expressed proteins in plasma from the same rabbits to corroborate their potential as diagnostic indicators. Similar analyses were performed in plasma from human subjects, to examine the suitability of these diagnostic indicators for transfer to the clinical setting. Eight proteins were found to be differentially expressed in CAS tissue, but only three were also altered in plasma samples from rabbits and humans: transitional endoplasmic reticulum ATPase, tropomyosin α-1 chain and L-lactate dehydrogenase B chain. Results of receiver operating characteristic curves showed the discriminative power of the scores, which increased when the three proteins were analyzed as a panel. Our study shows that a molecular panel comprising three proteins related to osteoblastic differentiation could have utility as a serum CAS indicator and/or therapeutic target.

Summary: Using a rabbit model of calcific aortic stenosis, we have defined a molecular panel of three proteins related to osteoblastic differentiation. Additionally, this panel has been confirmed in human samples.

New classification of geometric ventricular patterns in severe aortic stenosis: Could it be clinically useful?

BACKGROUND

In severe aortic stenosis, different left ventricle (LV) remodeling patterns as a response to pressure overload have distinct hemodynamic profiles, cardiac function, and outcomes. The most common classification considers LV relative wall thickness and LV mass index to create 4 different groups. A new classification including also end-diastolic volume index has been recently proposed.

AIM

To describe the prevalence of the newly identified remodeling patterns in patients with severe aortic stenosis and to evaluate their clinical relevance according to symptoms.

METHODS

We analyzed 286 consecutive patients with isolated severe aortic stenosis. Current guidelines were used for echocardiographic evaluation. Symptoms were defined as the presence of angina, syncope, or NYHA class III-IV.

RESULTS

The mean age was 75 ± 9 years, 156 patients (54%) were men, while 158 (55%) were symptomatic. According to the new classification, the most frequent remodeling pattern was concentric hypertrophy (57.3%), followed by mixed (18.9%) and dilated hypertrophy (8.4%). There were no patients with eccentric remodeling; only 4 patients had a normalLV geometry. Symptomatic patients showed significantly more mixed hypertrophy (P < .05), while the difference regarding the prevalence of the other patterns was not statistically significant. When we analyzed the distribution of the classic 4 patterns stratified by the presence of symptoms, however, we did not find a significant difference (P = .157).

CONCLUSIONS

The new classification had refined the description of different cardiac geometric phenotypes that develop as a response to pressure overload. It might be superior to the classic 4 patterns in terms of association with symptoms.

Aortic Stenosis, a Left Ventricular Disease: Insights from Advanced Imaging

Aortic stenosis (AS) is the most common primary valve disorder in the elderly with an increasing prevalence. It is increasingly clear that it is also a disease of the left ventricle (LV) rather than purely the aortic valve. The transition from left ventricular hypertrophy to fibrosis results in the eventual adverse effects on systolic and diastolic function. Appropriate selection of patients for aortic valve intervention is crucial, and current guidelines recommend aortic valve replacement in severe AS with symptoms or in asymptomatic patients with left ventricular ejection fraction (LVEF) <50 %. LVEF is not a sensitive marker and there are other parameters used in multimodality imaging techniques, including longitudinal strain, exercise stress echo and cardiac MRI that may assist in detecting subclinical and subtle LV dysfunction. These findings offer potentially better ways to evaluate patients, time surgery, predict recovery and potentially offer targets for specific therapies. This article outlines the pathophysiology behind the LV response to aortic stenosis and the role of advanced multimodality imaging in describing it.

The role of cardiac biochemical markers in aortic stenosis

Calcified aortic stenosis is one of the most common causes of heart failure in the elderly. Current guidelines recommend aortic valve replacement in patients with severe disease and evidence of decompensation based on either symptoms or impaired systolic ejection fraction. However, symptoms are often subjective whilst impaired ejection fraction is not a sensitive marker of ventricular decompensation. Interest has surrounded the use of cardiac biochemical markers as objective measures of left ventricular decompensation in aortic stenosis. We will first examine mechanisms of release of biochemical markers associated with myocardial wall stress (BNP/NT-proBNP), myocardial fibrosis (markers of collagen metabolism, galectin-3, soluble ST2) and myocyte death/myocardial ischemia (high-sensitivity cardiac troponins, heart-type fatty acid binding protein, myosin-binding protein C); and discuss future directions of these markers.

A clinical risk score of myocardial fibrosis predicts adverse outcomes in aortic stenosis

AIMS

Midwall myocardial fibrosis on cardiovascular magnetic resonance (CMR) is a marker of early ventricular decompensation and adverse outcomes in aortic stenosis (AS). We aimed to develop and validate a novel clinical score using variables associated with midwall fibrosis.

METHODS AND RESULTS

One hundred forty-seven patients (peak aortic velocity (Vmax) 3.9 [3.2,4.4] m/s) underwent CMR to determine midwall fibrosis (CMR cohort). Routine clinical variables that demonstrated significant association with midwall fibrosis were included in a multivariate logistic score. We validated the prognostic value of the score in two separate outcome cohorts of asymptomatic patients (internal: n = 127, follow-up 10.3 [5.7,11.2] years; external: n = 289, follow-up 2.6 [1.6,4.5] years). Primary outcome was a composite of AS-related events (cardiovascular death, heart failure, and new angina, dyspnoea, or syncope). The final score consisted of age, sex, Vmax, high-sensitivity troponin I concentration, and electrocardiographic strain pattern [c-statistic 0.85 (95% confidence interval 0.78-0.91), P < 0.001; Hosmer-Lemeshow χ(2) = 7.33, P = 0.50]. Patients in the outcome cohorts were classified according to the sensitivity and specificity of this score (both at 98%): low risk (probability score <7%), intermediate risk (7-57%), and high risk (>57%). In the internal outcome cohort, AS-related event rates were >10-fold higher in high-risk patients compared with those at low risk (23.9 vs. 2.1 events/100 patient-years, respectively; log rank P < 0.001). Similar findings were observed in the external outcome cohort (31.6 vs. 4.6 events/100 patient-years, respectively; log rank P < 0.001).

CONCLUSION

We propose a clinical score that predicts adverse outcomes in asymptomatic AS patients and potentially identifies high-risk patients who may benefit from early valve replacement.

Coexisting cardiac diseases and pressure recovery phenomenon contribute to discrepancy between the echocardiographic severity of aortic stenosis and left ventricular hypertrophy

BACKGROUND

Assessing left ventricular (LV) hypertrophy (LVH) is an important step in the echocardiographic diagnosis of aortic stenosis (AS). We aimed to investigate the causes of discrepancies between the degrees of AS and LVH.

METHODS

The study subjects consisted of 149 consecutive patients with AS having aortic valve area <2.0 cm(2) (mean age 72.5 ± 11.9 years, 67 men and 82 women). Coexisting cardiac diseases were determined based on echocardiographic findings and comprehensive clinical judgment. Echocardiographic measurements included LV mass index (LVMI), aortic valve area index (AVAI), transaortic mean pressure gradient (MPG), valvulo-arterial impedance (Zva), energy loss coefficient (ELCo), and energy loss index (ELI).

RESULTS

LVMI was not significantly correlated with AVAI and Zva, and had a weak correlation with MPG (r = 0.305, p = 0.0001). There were 55 patients in group A (non-severe AS without significant LVH), 58 in group B (non-severe AS with significant LVH), 7 in group C (severe AS without significant LVH), and 29 in group D (severe AS with significant LVH). Coexisting cardiac diseases were more frequently observed (p = 0.0003) in group B (50 %) than in group A (18 %). In group C, ELCo and (ELI - AVAI)/ELI were significantly greater than in group D (p = 0.043 and 0.007, respectively).

CONCLUSION

Significant LVH seen in less than moderate AS is often due to coexisting cardiac diseases, and there may be an overestimation of AS severity due to pressure recovery among patients with apparently severe AS who do not have significant LVH.

The novel two-dimensional strain reflects improvement and remodeling of left-ventricular function better than conventional echocardiographic parameters after aortic valve repair in pediatric patients

We aimed to evaluate the outcome and regional and global left-ventricular (LV) function after aortic valve repair in children with congenital aortic valve disease. Thirty-two consecutive patients with a mean age of 12.62 years (4 months to 18 years) undergoing aortic valve repair due to valve stenosis (AS group, n = 21) or aortic regurgitation (AR group, n = 11) were studied during a follow-up period of 12 months regarding change and adaptation of myocardial function using conventional and novel echocardiographic methods, including two-dimensional (2D) strain echocardiogram. Conventional and 2D strain echocardiographic studies were performed and analyzed off-line using commercially available software (EchoPac 6.1.0, GE). Peak aortic valve gradient decreased from 62.04 ± 30.34 mmHg before surgery to 22.80 ± 14.13 mmHg 2 weeks after surgery and to 35.73 ± 22.11 mmHg 12 months after surgery (p = 0.01). The degree of AR decreased significantly to grade 0 in 20 children and to grade I in 12. There was a significant decrease of thickness of the interventricular septum (IVS) and posterior wall resulting in improvement of LV mass index (p = 0.007, p = 0.043, and p = 0.001, respectively). Significant decrease of myocardial thickness was found, especially in the IVS, in the AS group (p = 0.008), and a significant decrease in LV end-diastolic dimension (EDD) was found in the AR group (p = 0.007). 2D strain analysis showed that global peak strain, global systolic strain rate, and global early diastolic strain rates improved significantly for all patients during the study period after aortic valve repair (p < 0.001, p = 0.037, and p = 0.018, respectively). The global strain and strain rates correlated significantly to IVS thickness (r = 0.002 and r = 0.003, respectively), LV mass index (r = 0.02 and r = 0.015, respectively), and EDD (r = 0.26 and r = 0.005, respectively). Aortic valve repair surgery in pediatric patients results in improvement of global and regional systolic and diastolic LV parameters, which was better shown by 2D strain parameters rather than conventional echocardiographic parameters.

Towards a re-definition of 'cardiac hypertrophy' through a rational characterization of left ventricular phenotypes: a position paper of the Working Group 'Myocardial Function' of the ESC

Many primary or secondary diseases of the myocardium are accompanied with complex remodelling of the cardiac tissue that results in increased heart mass, often identified as cardiac 'hypertrophy'. Although there have been numerous attempts at defining such 'hypertrophy', the present paper delineates the reasons as to why current definitions of cardiac hypertrophy remain unsatisfying. Based on a brief review of the underlying pathophysiology and tissue and cellular events driving myocardial remodelling with or without changes in heart dimensions, as well as current techniques to detect such changes, we propose to restrict the use of the currently popular term 'hypertrophy' to cardiac myocytes that may or may not accompany the more complex tissue rearrangements leading to changes in shape or size of the ventricles, more broadly referred to as 'remodelling'. We also discuss the great potential of genetically modified (mouse) models as tools to define the molecular pathways leading to the different forms of left ventricle remodelling. Finally, we present an algorithm for the stepwise assessment of myocardial phenotypes applicable to animal models using well-established imaging techniques and propose a list of parameters most suited for a critical evaluation of such pathophysiological phenomena in mouse models. We believe that this effort is the first step towards a much auspicated unification of the terminology between the experimental and the clinical cardiologists.

Age-related changes in aortic valve with emphasis on the relation between pressure loading and thickened leaflets of the aortic valves

BACKGROUND

The information of the prevalence of TAV and its relation to aortic stenosis in a large-scale human population is limited.

METHODS

An echocardiographic study was performed prospectively in 2850 subjects to determine the relationship between age and the thickened aortic valves (TAV). Another simulated study was designed to test the hypothesis that the noncoronary leaflet may have a greater diastolic loading than the right or left coronary leaflet.

RESULTS

The prevalence of TAV in this population was 14.4% (410/2850). It was 0% in the <39 years old; however, the prevalence of TAV increased progressively with age: it was 10.0% in the middle age group, 17.0% in the elderly group, and 53.7% in the octogenarian group (Chi-square test for linear trend, chi2=67.10, p<0.001). A greater frequency of TAV was noted at noncoronary leaflet (57.0%) than at either right (22.3%) or left (20.6%) coronary leaflet (chi2=5.99, df=2, p<0.001). The prevalence of aortic stenosis (AS) tended to increase with age (Chi-square test for linear trend, chi2=37.85, p<0.001). The simulated study demonstrated that the sinus of Valsalva without a coronary leaflet had a higher pressure loading than that with a coronary leaflet.

CONCLUSION

This study demonstrates that the prevalences of TAV and AS increase progressively with age. A greater frequency of TAV is found at the noncoronary leaflet than at either the right or left coronary leaflet. The simulated study supports our hypothesis that the noncoronary leaflet may bear a greater pressure loading than either the left or right coronary leaflet.

Impact of left ventricular hypertrophy late after aortic valve replacement for aortic stenosis on cardiovascular morbidity and mortality

AIMS

The goal of this study was to assess the prevalence of left ventricular (LV) hypertrophy in patients with aortic stenosis late (>6 months) after aortic valve replacement and its impact on cardiac-related morbidity and mortality.

METHODS AND RESULTS

In a single tertiary centre, echocardiographic data of LV muscle mass were collected. Detailed information of medical history and angiographic data were gathered. Ninety-nine of 213 patients (46%) had LV hypertrophy late (mean 5.8 +/- 5.4 years) after aortic valve replacement. LV hypertrophy was associated with impaired exercise capacity, higher New York Heart Association dyspnoea class, a tendency for more frequent chest pain expressed as higher Canadian Cardiovascular Society class, and more rehospitalizations. 24% of patients with normal LV mass vs. 39% of patients with LV hypertrophy reported cardiac-related morbidity (p = 0.04). In a multivariate logistic regression model, LV hypertrophy was an independent predictor of cardiac-related morbidity (odds ratio 2.31, 95% CI 1.08 to 5.41), after correction for gender, baseline ejection fraction, and coronary artery disease and its risk factors. Thirty seven deaths occurred during a total of 1959 patient years of follow-up (mean follow-up 9.6 years). Age at aortic valve replacement (hazard ratio 1.85, 95% CI 1.39 to 2.47, for every 5 years increase in age), coexisting coronary artery disease at the time of surgery (hazard ratio 3.36, 95% CI 1.31 to 8.62), and smoking (hazard ratio 4.82, 95% CI 1.72 to 13.45) were independent predictors of overall mortality late after surgery, but not LV hypertrophy.

CONCLUSIONS

In patients with aortic valve replacement for isolated aortic stenosis, LV hypertrophy late after surgery is associated with increased morbidity.

Left ventricular hypertrophy in aortic valve stenosis: preventive or promotive of systolic dysfunction and heart failure?

AIMS

In aortic stenosis (AS), left ventricular (LV) hypertrophy is considered a compensatory response helping maintain systolic function. Recent research in experimental AS suggests, however, that LV hypertrophy is not necessary to sustain LV contractions but may in fact be maladaptive. The present work aimed to clarify the role of LV hypertrophy in AS-related heart failure (HF) in man.

METHODS AND RESULTS

We studied 137 adult patients with isolated AS undergoing pre-operative echocardiography and cardiac catheterization. HF was diagnosed by the European criteria and LV hypertrophy by sex-specific limits of echocardiographic LV mass. The higher the LV mass was, the poorer was the LV ejection fraction (beta=-0.26, P< 0.001, linear regression) and the greater the likelihood of HF independent of the severity of AS (P< 0.001, logistic regression). In the subgroup of critical AS (valve area <0.4 cm(2)/m(2), n=85), patients with absent LV hypertrophy (n=19) had better preserved ejection fraction (mean+/-SE, 64+/-3 vs. 57+/-2%, P=0.045) and less HF (16 vs. 48%, P=0.025) than patients with LV hypertrophy (n=66).

CONCLUSION

In isolated AS, increased LV mass predicts the presence of systolic dysfunction and HF independent of the severity of valvular obstruction. LV hypertrophy may be maladaptive rather than beneficial in AS in man.

ACE inhibition in aortic stenosis: dangerous medicine or golden opportunity?

Conventionally angiotensin-converting enzyme (ACE) inhibitors are contraindicated in patients with aortic stenosis. Abundant evidence is now available showing that angiotensin II has a central role in the development of left ventricular hypertrophy (LVH), myocardial contractile failure and diastolic dysfunction in response to pressure overload. In animal models, ACE inhibitors have been shown to attenuate these pathological responses. In humans there is no such evidence available, however uncontrolled studies have shown that these agents are not only tolerated but are associated with acute improvements in haemodynamics and diastolic function. Further studies are merited to assess the possible role of ACE inhibitors in aortic stenosis both before and after valve replacement. Potential benefits may include prevention of LVH, improved diastolic function, reduction of arrhythmias and preservation of left ventricular function.

Angiotensin-converting enzyme gene polymorphism influences degree of left ventricular hypertrophy and its regression in patients undergoing operation for aortic stenosis

Insertion (I)/deletion (D) polymorphism of the angiotensin-converting enzyme (ACE) gene has been associated with increased left ventricular hypertrophy (LVH) in patients with cardiomyopathy and congestive heart failure. Patients with aortic stenosis (AS) have varying degrees of LVH at a given valve area. The aim of this study was to examine the relation between ACE gene polymorphism and the degree of LVH in patients undergoing operation for AS. Eighty-two patients who underwent operation for AS with a stentless valve were followed prospectively with echocardiographic assessments of left ventricular mass index (LVMI). ACE gene polymorphism was determined by polymerase chain reaction. The genotype (DD, ID, and II) frequency was the same as in healthy controls. The pressure difference across the aortic valve did not differ between genotypes. Patients with the DD genotype of the ACE gene had a higher LVMI (197 +/- 47 g/m2) preoperatively than those with ID (175 +/- 41 g/m2) or II (155 +/- 43 g/m2) genotypes (p = 0.01). LVMI decreased significantly in DD (p <0.001) and ID (p <0.001) genotypes but not in the II genotype during follow-up (mean 15 months). There was a significant difference in regression of LVMI over time between genotypes (p = 0.0056), with no significant difference between genotypes at follow-up. The DD genotype of the ACE gene is associated with increased preoperative LVH in patients treated surgically for AS. The DD genotype appears to be an important factor which increases hypertrophic myocardial reactivity to pressure overload.