v3.26.3
Segment Reporting - Summary of Segment Loss Including Significant Segment Expenses (Details) - USD ($)
$ in Thousands
 3 Months Ended 9 Months Ended
Sep. 30, 2026
Sep. 30, 2025
Sep. 30, 2026
Sep. 30, 2025
Segment Reporting [Line Items]        
Research and development compensation and benefits [1] $ 23,816 $ 13,293 $ 56,109 $ 35,743
Research and development - other 13,499 11,949 34,596 24,986
Total Research and development expense 64,359 49,139 165,791 103,752
General and administrative expense compensation and benefits [1] 17,019 5,346 38,439 26,295
General and administrative expense - other 5,226 4,589 16,316 12,230
Total general and administrative expense 22,245 9,935 54,755 38,525
Change in fair value of contingent milestone liabilities (21,789) 0 21,740 0
Operating Expenses 64,815 59,074 242,286 142,277
Other income/expense [2] (6,247) 1,082 (11,411) (2,490)
Loss before income taxes 58,568 60,156 230,875 139,787
Danicamtiv        
Segment Reporting [Line Items]        
Program expenses 11,739 7,532 35,294 8,416
Ataciguat        
Segment Reporting [Line Items]        
Program expenses 10,898 7,453 27,515 17,287
Tonlamarsen        
Segment Reporting [Line Items]        
Program expenses $ 4,407 $ 8,912 $ 12,277 $ 17,320
[1] Includes stock-based compensation expense
[2] Other income (expense) for the three and nine months ended September 30, 2026 primarily includes interest income. Other income (expense) for the three and nine months ended September 30, 2025 primarily includes bargain purchase gain, warrant issuance expense, change in fair value of Series A Preferred Stock tranche obligations and interest income.