For me, panic attacks were scariest when I had no idea what they were or while I was (or am) still uncertain that they're panic attacks. The fear that they're something worse drove the feedback loop.
Being able to identify them as anxiety (focusing quite acutely on constellations of familiar symptoms and reasoning about how they might or might not be anxiety-related) made me ride all subsequent ones out successfully, and they also grew milder and more short-lived.
If a mobile device acting as crappy medical equipment told me I was having heart problems, though, my anxiety would definitely increase.
Being able to identify them as anxiety (focusing quite acutely on constellations of familiar symptoms and reasoning about how they might or might not be anxiety-related) made me ride all subsequent ones out successfully, and they also grew milder and more short-lived.
If a mobile device acting as crappy medical equipment told me I was having heart problems, though, my anxiety would definitely increase.