** William Blair initiates coverage of AI diagnostics firm Heartflow HTFL.O with an "outperform" rating, citing growth potential from its AI-enabled, non-invasive cardiac diagnostics platform

** Brokerage says the platform provides actionable clinical information without invasive tests, helping guide diagnosis and management of coronary artery disease

** Says the technology is backed by extensive clinical data, adds HTFL is already executing on trials to more than double its total addressable market with the estimated $6 billion opportunity in asymptomatic screening

** Points to a software-like business model, with a pay-per-use structure and 80%-plus gross margins, allowing scalability with limited incremental costs

** As of last close, HTFL down 1.7% YTD