Is Regression of Left Ventricular Hypertrophy Really a Good Thing for Patients With Hypertrophic Cardiomyopathy?: The Emerging Mavacamten Story

Mavacamten, a precision medicine for hypertrophic cardiomyopathy: From a motor protein to patients

Hypertrophic cardiomyopathy (HCM) is a primary myocardial disorder characterized by left ventricular hypertrophy, hyperdynamic contraction, and impaired relaxation of the heart. These functional derangements arise directly from altered sarcomeric function due to either mutations in genes encoding sarcomere proteins, or other defects such as abnormal energetics. Current treatment options do not directly address this causal biology but focus on surgical and extra-sarcomeric (sarcolemmal) pharmacological symptomatic relief. Mavacamten (formerly known as MYK-461), is a small molecule designed to regulate cardiac function at the sarcomere level by selectively but reversibly inhibiting the enzymatic activity of myosin, the fundamental motor of the sarcomere. This review summarizes the mechanism and translational progress of mavacamten from proteins to patients, describing how the mechanism of action and pharmacological characteristics, involving both systolic and diastolic effects, can directly target pathophysiological derangements within the cardiac sarcomere to improve cardiac structure and function in HCM. Mavacamten was approved by the Food and Drug Administration in April 2022 for the treatment of obstructive HCM and now goes by the commercial name of Camzyos. Full information about the risks, limitations, and side effects can be found at www.accessdata.fda.gov/drugsatfda_docs/label/2022/214998s000lbl.pdf.

Risk Factors for Left Ventricular Hypertrophy in Patients with Diabetic Kidney Disease: A Multi-Center Study

Objective

One of the earliest echocardiographic features of the left ventricle explored extensively was left ventricular hypertrophy (LVH). Numerous studies have identified a few risk factors for LVH, however, there are few for people with diabetic kidney disease (DKD). Therefore, we evaluated the risk factors in DKD patients with LVH by analyzing laboratory data and clinical traits.

Methods

In total, 500 DKD patients in the Baoding area from February 2016 and June 2020 were admitted and classified as an experimental group (240 cases, LVH group) and a control group (260 cases, non-LVH group). The clinical parameters and laboratory tests of the participants were collected and analyzed retrospectively.

Results

Compared with the control group, low-density lipoprotein (LDL), body mass index (BMI), intact parathyroid hormone (iPTH), systolic blood pressure, and 24-hour urine protein were higher in the experimental group (all P<0.01). Multivariable logistic regression analysis results confirmed that high BMI (OR=1.332, 95% CI 1.016-1.537, P=0.006), LDL (OR=1.279, 95% CI 1.008-1.369, P=0.014) and 24-hour urine proteins (OR=1.446, 95% CI 1.104-1.643, P=0.016) were statistically significant. The ROC analysis illustrated that the optimum cutoff value of BMI, LDL, and 24-hour urine proteins for diagnosis of LVH in patients with DKD was 27.36 kg/m², 4.18 mmol/L, and 1.42 g respectively.

Conclusion

The increase in BMI, LDL, and 24-hour urine proteins quantification are independent risk factors for LVH in patients with DKD.

Ventricular Septal Myectomy for Obstructive Hypertrophic Cardiomyopathy (Analysis Spanning 60 Years Of Practice): AJC Expert Panel

Surgical myectomy remains the time-honored primary treatment for hypertrophic cardiomyopathy patients with drug refractory limiting symptoms due to LV outflow obstruction. Based on >50 years experience, surgery reliably reverses disabling heart failure by permanently abolishing mechanical outflow impedance and mitral regurgitation, with normalization of LV pressures and preserved systolic function. A consortium of 10 international currently active myectomy centers report about 11,000 operations, increasing significantly in number over the most recent 15 years. Performed in experienced multidisciplinary institutions, perioperative mortality for myectomy has declined to 0.6%, becoming one of the safest currently performed open-heart procedures. Extended myectomy relieves symptoms in >90% of patients by ≥ 1 NYHA functional class, returning most to normal daily activity, and also with a long-term survival benefit; concomitant Cox-Maze procedure can reduce the number of atrial fibrillation episodes. Surgery, preferably performed in high volume clinical environments, continues to flourish as a guideline-based and preferred high benefit: low treatment risk option for adults and children with drug refractory disabling symptoms from obstruction, despite prior challenges: higher operative mortality/skepticism in 1960s/1970s; dual-chamber pacing in 1990s, alcohol ablation in 2000s, and now introduction of strong negative inotropic drugs potentially useful for symptom management.