Dose-Blinded Myosin Inhibition in Patients With Obstructive Hypertrophic Cardiomyopathy Referred for Septal Reduction Therapy: Outcomes Through 32 Weeks

BACKGROUND

Septal reduction therapy (SRT) in patients with intractable symptoms from obstructive hypertrophic cardiomyopathy (oHCM) is associated with variable morbidity and mortality. The VALOR-HCM trial (A Study to Evaluate Mavacamten in Adults with Symptomatic Obstructive Hypertrophic Cardiomyopathy Who Are Eligible for Septal Reduction Therapy) examined the effect of mavacamten on the need for SRT through week 32 in oHCM.

METHODS

A double-blind randomized placebo-controlled multicenter trial at 19 US sites included patients with oHCM on maximal tolerated medical therapy referred for SRT with left ventricular outflow tract gradient ≥50 mm Hg at rest or provocation (enrollment, July 2020-October 2021). The group initially randomized to mavacamten continued the drug for 32 weeks, and the placebo group crossed over to dose-blinded mavacamten from week 16 to week 32. Dose titrations were based on investigator-blinded echocardiographic assessment of left ventricular outflow tract gradient and left ventricular ejection fraction. The principal end point was the proportion of patients proceeding with SRT or remaining guideline eligible at 32 weeks in both treatment groups.

RESULTS

From the 112 randomized patients with oHCM, 108 (mean age, 60.3 years; 50% men; 94% in New York Heart Association class III/IV) qualified for week 32 evaluation (56 in the original mavacamten group and 52 in the placebo cross-over group). After 32 weeks, 6 of 56 patients (10.7%) in the original mavacamten group and 7 of 52 patients (13.5%) in the placebo cross-over group met SRT guideline criteria or elected to undergo SRT. After 32 weeks, a sustained reduction in resting left ventricular outflow tract gradient (-33.0 mm Hg [95% CI, -41.1 to -24.9]) and Valsalva left ventricular outflow tract gradient (-43.0 mm Hg [95% CI, -52.1 to -33.9]) was observed in the original mavacamten group. A similar reduction in resting (-33.7 mm Hg [95% CI, -42.2 to -25.2]) and Valsalva (-52.9 mm Hg [95% CI, -63.2 to -42.6]) gradients was quantified in the cross-over group after 16 weeks of mavacamten. After 32 weeks, improvement by ≥1 New York Heart Association class was observed in 48 of 53 patients (90.6%) in the original mavacamten group and 35 of 50 patients (70%) after 16 weeks in the cross-over group.

CONCLUSIONS

In severely symptomatic patients with oHCM, 32 weeks of mavacamten treatment showed sustained reduction in the proportion proceeding to SRT or remaining guideline eligible, with similar effects observed in patients who crossed over from placebo after 16 weeks.

REGISTRATION

URL: https://www.

CLINICALTRIALS

gov; Unique identifier: NCT04349072.

Intramyocardial ventricular septal hematoma. Unexpected complication

Any step in cardiac surgery may have potentially catastrophic consequences. All treatment options need to be carefully evaluated because the most aggressive is not always the best one. We present the case of a 63-year-old man who suffered an interventricular septum hematoma causing left ventricular tract obstruction, secondary to a left ventricular vent. The lesion could be repaired by closing the entry point.

Aneurysm of the sinus of Valsalva dissecting into the intraventricular septum

Aneurysm of the sinus of Valsalva is an uncommon entity and especially rare when it dissects into the intraventricular septum. This uncommon clinical manifestation often takes a drastic clinical course with life-threatening arrhythmia, coronary ischemia, rupture, and heart failure. We present the case of a 36-year-old man with an aneurysm of the sinus of Valsalva dissecting into the intraventricular septum, which induced severe aortic insufficiency and heart block.

Giant right atrial lipoma mimicking tamponade

Cardiac lipomas are rarely encountered. They are mostly asymptomatic and may be discovered incidentally. We describe the case of a 56 year-old man with a presentation similar to tamponade. He had decreased heart sounds, global cardiomegaly, and oligemic lung fields. Echocardiography showed a 110 × 75-mm mass attached to the interatrial septum, almost completely occupying the right atrium. Chest computed tomography showed a large homogeneous low-attenuation mass with thin septa, originating from interatrial septum and filling the right atrium, consistent with lipoma. The patient underwent surgery for resection of the tumor. Pathologic examination was consistent with cardiac lipoma.

Posterior ventricular septal defect in presence of cardiogenic shock: early implantation of the impella recover LP 5.0 as a bridge to surgery

Urgent repair (within 48 hr after diagnosis) of posterior ventricular septal defect in the presence of cardiogenic shock, consequent to acute myocardial infarction, is associated with a very high mortality rate. The use of left ventricular mechanical support devices has the potential to impart hemodynamic stability and to delay surgical treatment until such time as scar tissue forms around the defect, sufficient to hold a suture patch.From May 2004 through July 2007, 5 patients who were in cardiogenic shock as a consequence of acute posterior ventricular septal defect underwent early implantation of a transfemoral microaxial Impella® Recover® LP 5.0 Support System as mechanical support (bridge to surgery).The mean duration of support by the left ventricular assist device was 14.4 ± 6 days. No one died during assistance. The device reduced left-to-right shunting, systolic pulmonary artery pressure, central venous pressure, and pulmonary capillary wedge pressure. Liver, kidney, and lung function improved, and the 30-day mortality rate was 40%.Although this is a retrospective study of a very small patient population, without benefit of a control group, it is the first report of its kind. This initial experience using the Impella Recover 5.0 in cases of cardiogenic shock due to posterior ventricular septal defect suggests that this conservative approach is a feasible and safe way to improve hemodynamic conditions and delay surgery. Further clinical experience is needed to confirm these early results.

The "1st septal unit" in hypertrophic obstructive cardiomyopathy: a newly recognized anatomo-functional entity, identified during recent alcohol septal ablation experience

In hypertrophic obstructive cardiomyopathy, selective and asymmetric hypertrophy results in a stenotic subaortic channel, which is further narrowed by a Venturi effect (suctioning of the anterior leaflet, manifested by systolic anterior motion of the mitral valve). Better understanding of these essential pathophysiologic mechanisms has led to the definition of a new anatomo-functional entity, the 1st septal unit, which consists of the basal interventricular septal hypertrophy and its related septal arterial branches. As an alternative to surgical myomectomy, alcohol septal ablation is an effective method of reducing subaortic stenosis and improving mitral valve function. After alcohol ablation, global negative remodeling of the hypertrophied left ventricle eventually ensues. This review presents specific anatomic and functional features of a newly identified pathophysiologic entity (the 1st septal unit) in relation to the clinical manifestations and natural history of hypertrophic obstructive cardiomyopathy. This relationship is also relevant during the performance of alcohol septal ablation interventions: related operative suggestions are provided for optimizing subaortic stenosis relief during septal ablation and for preventing complications.