"Anxiety may lead to fear of another cardiac event and stop people from being active," said study author Angela Rao, from the University of Technology Sydney in Australia. "Depression and anxiety can also impair the ability to retain new information needed to make health-related behavior changes."
Rao's team followed nearly 4,800 patients undergoing cardiac rehabilitation at two Sydney hospitals between 2006 and 2017.
A mental health assessment showed that 18% 28% and 13% of the patients had moderate to extremely severe depression, anxiety or stress, respectively.
Patients with moderate depression were much more likely to drop out of cardiac rehabilitation (24%) than those with no or mild symptoms (13%). This was also seen in patients with anxiety (32% vs. 23%) and stress (18% vs. 10%).
About half of the patients with moderate depression or anxiety who actually completed cardiac rehabilitation did not have significant improvements in their mental health conditions.
The study was published recently in the European Journal of Preventive Cardiology.
"Heart patients living with depression are more likely to feel despondent and hopeless, which reduces their ability to manage their symptoms," Rao said in a journal news release.
"They may minimize successes and exaggerate failures, thereby reducing their motivation to exercise and complete a cardiac rehabilitation program," she explained.
Heart attack survivors should receive support to quit smoking, get physically active, improve their eating habits, reduce stress, and control blood pressure and cholesterol, all of which can be accomplished through cardiac rehabilitation, the study authors noted.
"Depression can dampen positive intentions to exercise even when receiving support from health professionals and being aware of the benefits," Rao said. "People with anxiety may underestimate their abilities -- for example, to walk on a treadmill during a rehabilitation class."
Doctors should screen for depression and anxiety at the start and end of cardiac rehabilitation in order to identify patients who extra help, she suggested.