Left atrial remodeling postseptal myectomy for severe obstructive hypertrophic cardiomyopathy: Analysis by two-dimensional speckle-tracking echocardiography

Impact of Aficamten on Echocardiographic Cardiac Structure and Function in Symptomatic Obstructive Hypertrophic Cardiomyopathy

BACKGROUND

Aficamten, a next-in-class cardiac myosin inhibitor, improved peak oxygen uptake (pVO2) and lowered resting and Valsalva left ventricular outflow (LVOT) gradients in adults with symptomatic obstructive hypertrophic cardiomyopathy (oHCM) in SEQUOIA-HCM (Phase 3 Trial to Evaluate the Efficacy and Safety of Aficamten Compared to Placebo in Adults With Symptomatic oHCM), a phase 3, multicenter, randomized, double-blinded, placebo-controlled study.

OBJECTIVES

The authors sought to evaluate the effect of aficamten on echocardiographic measures of cardiac structure and function in SEQUOIA-HCM.

METHODS

Serial echocardiograms were performed over 28 weeks in patients randomized to receive placebo or aficamten in up to 4 individually titrated escalating doses (5-20 mg daily) over 24 weeks based on Valsalva LVOT gradients and left ventricular ejection fraction (LVEF).

RESULTS

Among 282 patients (mean age 59 ± 13 years; 41% female, 79% White, 19% Asian), mean LVEF was 75% ± 6% with resting and Valsalva LVOT gradients of 55 ± 30 mm Hg and 83 ± 32 mm Hg, respectively. Over 24 weeks, aficamten significantly lowered resting and Valsalva LVOT gradients, and improved left atrial volume index, lateral and septal e' velocities, and lateral and septal E/e' (all P ≤ 0.001). LV end-systolic volume increased and wall thickness decreased (all P ≤ 0.003). Aficamten resulted in a mild reversible decrease in LVEF (-4.8% [95% CI: -6.4 to -3.3]; P < 0.001) and absolute LV global circumferential strain (-3.7% [95% CI: 1.8-5.6]; P < 0.0010), whereas LV global longitudinal strain was unchanged. Several measures, including LVEF, LVOT gradients, and E/e' returned to baseline following washout. Among those treated with aficamten, improved pVO2 and reduction in N-terminal pro-B-type natriuretic peptide (NT-proBNP) were associated with improvement in lateral e' velocity and septal and lateral E/e' (all P < 0.03), whereas improvement in Kansas City Cardiomyopathy Questionnaire Clinical Summary Scores (KCCQ-CSS) was associated with a decrease in both LVOT gradients (all P < 0.001).

CONCLUSIONS

Compared with placebo, patients receiving aficamten demonstrated significant improvement in LVOT gradients and measures of LV diastolic function, and several of these measures were associated with improvements in pVO2, KCCQ-CSS, and NT-proBNP. A modest decrease in LVEF occurred yet remained within normal range. These findings suggest aficamten improved multiple structural and physiological parameters in oHCM without significant adverse changes in LV systolic function. (Phase 3 Trial to Evaluate the Efficacy and Safety of Aficamten Compared to Placebo in Adults With Symptomatic oHCM [SEQUOIA-HCM]; NCT05186818).

Evolving Contemporary Management of Atrial Fibrillation in Hypertrophic Cardiomyopathy

Atrial fibrillation (AF) is the most common sustained arrhythmia in hypertrophic cardiomyopathy (HCM) with clinical and subclinical episodes occurring in nearly one-half of patients. AF in HCM historically has been characterized as a decisive disease complication associated with substantial risk for thromboembolic stroke and increased morbidity and mortality. However, there have been many advances in treatment strategy resulting in improved outcomes for this patient group. For example, stroke risk in HCM has been greatly reduced by using systemic oral anticoagulation initiated after the first clinical (symptomatic) AF episode, usually with preference given to direct anticoagulants over warfarin. In contrast, stroke risk scoring systems (such as CHA2DS2-VASc score) are not informative in HCM given the substantial potential for stroke events in patients with low scores, and therefore should not be used for anticoagulation decisions in this disease. A novel risk score specifically designed for HCM (HCM-AF score) can reliably identify most patients with HCM at risk for future AF. Although a strategy focused on controlling ventricular rate is effective in asymptomatic (or minimally symptomatic) patients with AF, restoring and maintaining sinus rhythm is required for most patients with marked AF symptom burden and impaired quality of life. Several antiarrhythmic drugs such as sotalol, disopyramide, and amiodarone, can be effective in suppressing AF episodes; albeit safe, long-term efficacy is supported by only limited data. Catheter AF ablation has emerged as an important treatment option for some patients, although freedom from AF after a single ablation is relatively low (35% at 3 years), multiple ablations and the concomitant use of antiarrhythmic drugs can control AF with more than two-thirds of patients maintaining sinus rhythm at 5 years. Surgical AF ablation with biatrial Cox-Maze IV performed as an adjunctive procedure during myectomy can reduce symptomatic AF episodes (70% of patients free from AF at 5 years). For the vast majority of patients who have HCM with AF, the implementation of contemporary therapies has allowed for improved quality of life and low HCM-related mortality.

Reverse remodeling of left atrium assessed by cardiovascular magnetic resonance feature tracking in hypertrophic obstructive cardiomyopathy after septal myectomy

BACKGROUND

Assessing the structure and function of left atrium (LA) is crucial in hypertrophic obstructive cardiomyopathy (HOCM) because LA remodeling correlates with atrial fibrillation. However, few studies have investigated the potential effect of myomectomy on LA phasic remodeling in HOCM after myectomy using cardiovascular magnetic resonance (CMR) feature tracking (FT). This study aims to evaluate the LA structural and functional remodeling with HOCM after myectomy by CMR-FT and to further investigate the determinants of LA reverse remodeling.

METHODS

In this single-center study, we retrospectively studied 88 patients with HOCM who received CMR before and after myectomy between January 2011 and June 2021. Preoperative and postoperative LA parameters derived from CMR-FT were compared, including LA reservoir function (total ejection fraction [EF], total strain [εs], peak positive strain rate [SRs]), conduit function (passive EF, passive strain [εe], peak early negative strain rate [SRe]) and booster function (booster EF, active strain [εa], late peak negative strain rate [SRa]). Eighty-six healthy participants were collected for comparison. Univariate and multivariate linear regression identified variables associated with the rate of change of εa.

RESULTS

Compared with preoperative parameters, LA reservoir function (total EF, εs, SRs), booster function (booster EF, εa, SRa), and SRe were significantly improved after myectomy (all P < 0.05), while no significant differences were observed in passive EF and εe. Postoperative patients with HOCM still had larger LA and worse LA function than healthy controls (all P < 0.05). After analyzing the rates of change in LA parameters, LA boost function, especially εa, showed the most dramatic improvement beyond the improvements in reservoir function, conduit function, and volume. In multivariable regression analysis, minimum LA volume index (adjusted β = - 0.39, P < 0.001) and Δleft ventricular outflow tract (LVOT) pressure gradient (adjusted β = - 0.29, P = 0.003) were significantly related to the rate of change of εa.

CONCLUSIONS

Patients with HOCM after septal myectomy showed LA reverse remodeling with a reduction in LA size and restoration in LA reservoir and booster function but unchanged LA conduit function. Among volumetric and functional changes, booster function had the greatest improvement postoperatively. Besides, preoperative LAVmin index and ΔLVOT might be potential factors associated with the degree of improvement in εa.

Left atrial function analysis in patients in sinus rhythm, normal left ventricular function and indeterminate diastolic function

Assessment of diastolic function by echocardiography may be indeterminate as demonstrated in previous studies where diastolic measurement is a discrepant. We aimed to assess whether left atrial (LA) function may contribute to left ventricle filling evaluation in patients with indeterminate diastolic function (IndtDFx). This retrospective study included 3 groups of patients based on diastolic function: normal diastolic function (NDFx), definite diastolic dysfunction (DDFx) and IndtDFx. All patients had sinus rhythm with left ventricular ejection fraction ≥ 45%. Diastolic function was determined according to the following echocardiographic parameters: mitral E', mitral E/E' ratio, LA maximal volume index, and pulmonary pressure. NDFx was defined as having less than 2 abnormal parameters, DDFx as more than 2 abnormal parameters, and IndtDFx as 2 abnormal parameters. LA function analysis was performed in all patients using echocardiographic 2D speckle tracking. Sixty seven patients were included in strain analysis. The DDFx group (n = 21) and IndtDFx (n = 19) were significantly different from NDFx (27) in some demographics, cardiovascular risk factors, presentation and echocardiographic parameters. Some of the phasic LA function (phasic LA volumes and strains) parameters in the IndtDFx group were similar to DDFx and significantly different from the NDFx group, while other parameters fell in between the two groups. Phasic LA minimal volume index was found to be associated with heart failure symptoms. The IndtDFx group is a heterogeneous group demonstrating clinical and echocardiographic profiles that closely resemble that of DDFx group. LA phasic function analysis may help in re-classification of patients with IndtDFx as actual DDFx or as NDFx.

ICE-Derived Left Atrial and Left Ventricular Endocardial and Myocardial Speckle Tracking Strain Patterns in Atrial Fibrillation at the Time of Radiofrequency Ablation

Objectives

Intracardiac echocardiography(ICE) has excellent imaging resolution and border recognition which increase strain measurement accuracy. We hypothesized that left atrial(LA) substrate and functional impairment can be detected by measuring LA strain deformation in patients with persistent and paroxysmal atrial fibrillation(AF), as compared to those with no AF. Strain deformation changes in LA and left ventricle(LV) can also be assessed post-ablation to determine its effect.

Methods

ICE-derived speckle tracking strain(STS) was prospectively performed in 96 patients, including 62 patients with AF(31 persistent and 31 paroxysmal AF) pre-/post-ablation, and 34 patients with no AF. We measured major strain parameters including longitudinal segmental(endo/myocardial) "average peak overall strain of all segments"(PkAll), peak strain rate(SR),and different time-to-peak strain in LA and LV images.

Results

At baseline, persistent AF patients had significantly lower(p<0.01) LA endocardial(4.3±2.5 vs. 20.3±8.9 and 25.5±12.9 %) and myocardial PkAll(4.4±2.6 vs. 15.7±7.2 and 20.9±9.2 %), endocardial(0.9±0.4 vs. 1.8±0.7 and 2.2±0.6 1/s) and myocardial peak SR(0.7±0.4 vs. 1.5±0.6 and 1.9±0.5 1/s), as compared to paroxysmal AF and no AF patients. After successful ablation, endo-/myocardial LA PkAll and peak SR were significantly improved, most dramatically in patients with persistent AF. LV endocardial/myocardial strain and SR also improved in AF patients post-ablation.

Conclusion

LA longitudinal strain(%)/SR(1/s) parameters in AF patients are more abnormal than those with no AF, suggesting LA substrate/functional damage. AF ablation improved LA strains/SR but with values in paroxysmal > persistent AF suggesting background LA damage in persistent AF.