Study author Ole Skov, a psychologist and PhD student in cardiac psychology at the University of Southern Denmark, Odense, Denmark said: “Medications help to control symptoms and prevent further heart problems so adherence is important. Patients with an implantable cardioverter defibrillator (ICD) who feel depressed or anxious should be encouraged to express their concerns, thoughts, and feelings and contact a health care professional who can screen them for distress to explore the best course of action. This could be referral to a psychologist or other measures.”

An ICD implantation is recommended for people at high risk of a life-threatening arrhythmia and for those who have had a sudden cardiac arrest. It is estimated that approximately one in every five patients with an ICD is affected by depression or anxiety.

Both mental health issues have been linked with an elevated risk of death in those with an ICD.

Most patients with an ICD are prescribed medication to manage their heart disease. Failure to take cardiac medications increases the risk of complications and death, making it crucial to identify patients who are more likely to stop taking their medication so that support measures can be initiated.

This study examined whether anxiety and depression at the time of ICD implantation are associated with medication adherence one year after receiving the device.

The study was a secondary analysis of the ACQUIRE-ICD randomised controlled trial of an eHealth intervention, which enrolled patients from all six implantation centres in Denmark.

Of 478 patients in the trial with an ICD or an ICD with cardiac resynchronisation therapy (CRT-D), 433 (91%) were taking at least one heart medication when their device was implanted.

These included beta-blockers, ACE inhibitors, statins and diuretics. Of the 433 patients, 322 patients (74%) completed assessments of medication adherence at both baseline (implantation) and 12 months after implantation and were included in the current analyses.

Medication adherence was measured by self-report using the Morisky Medication Adherence Scale (MMAS) with scores ranging from 0 to 8. Low, medium and high adherence were defined as scores below 6, 6 to <8, and 8, respectively. Depression and anxiety were assessed at baseline with the Patient Health Questionnaire 9 (PHQ-9; scores 0-27) and the Generalised Anxiety Disorder (GAD-7; scores 0-21) scale, with higher scores indicating more symptoms. Both were used as continuous measures, and patients were not categorized as depressed/not depressed or anxious/not anxious.

The average age of participants was 60 years and 84% were men. Medication adherence was generally medium to high at baseline (6.8% low adherence, 40.1% medium adherence, 53.1% high adherence; average MMAS score 7.31) and at 12 months (8.1% low adherence, 37.3% medium adherence, 54.6% high adherence; average MMAS score 7.33).

The researchers analysed the association between mental health scores and medication adherence after adjusting for baseline MMAS score, sex, trial intervention group, heart failure severity and implantation centre. Depression scores at baseline were negatively associated with medication adherence at 12 months (p=0.02). The association with anxiety was not statistically significant.

Skov said: “Patients with higher levels of depressive symptoms at the time of ICD implantation were less likely to be taking their heart medications one year later. The effect of depression was statistically significant but small, which is not surprising given the complexity and multitude of factors involved in medication adherence.”

He concluded: “These results highlight the importance of considering the psychological status of people receiving an ICD. Those with symptoms of depression at the time of implantation could be at risk of discontinuing their heart medications, even if they are taking them initially, and may need extra support.”