Inclusion Criteria:

- For MYH7 and TTN cohorts, must have diagnosis of primary DCM (dilated cardiomyopathy),
clinically stable and due to probably disease-causing variant of MYH7 or TTN

- Has adequate acoustic windows for echocardiography

- Maximum of 3 family members with same variant can be enrolled

- For the cohort of primary DCM due to causalities other than MYH7 and TTN, participant
must have diagnosis of primary DCM with a cause not related to MYH7 or TTN variants

Exclusion Criteria:

- Significant structural cardiac abnormalities including valvar dysfunction on Screening
transthoracic echo(s)

- Routinely scheduled outpatient intravenous (IV) infusions for heart failure (e.g.,
inotropes, afterload reduction, or diuretics)

- Presence of protocol specified laboratory abnormalities at Screening

- Recent acute coronary syndrome or angina pectoris (<90 days)

- Recent hospitalization for heart failure (<90 days)

-History of advanced heart failure therapy (ie, a heart transplant or left ventricular assisted device, LVAD therapy)

Note: Other protocol defined Inclusion/Exclusion Criteria may apply.

Eligibility last updated 2/6/2024. Questions regarding updates should be directed to the study team contact.