It may be hard to imagine that the bull run's days are numbered with the Dow locking in its 54th record close for the year.

Bessemer Trust's Rebecca Patterson senses a threat: A sudden rise in inflation.

"If inflation ticks up [and] central banks respond, then I think we have a much more volatile picture," the firm's chief investment officer said Tuesday on CNBC's "Futures Now."

The situation wouldn't be as problematic if growth were to keep up with inflation, she said, but added: "Growth is just kind of holding steady."

In a note to "Futures Now," Patterson wrote: "Credit markets are crowded and vulnerable to sharply rising rates. So too are pockets of the consumer sector. Higher rates and a resulting stronger dollar could also throw EM [emerging markets] assets into a bad place."

For now, Patterson said she's "constructive" on the stock market into 2018. But the picture gets hazier after that.

"I think we're going to get a more risky picture for equities again," Patterson said.