The purpose of this 2-group randomized clinical trial is to: 1) examine the feasibility and acceptability of a 3-month positive-emotion focused therapy (Quality of Life Therapy) modified specifically for patients with implantable cardioverter defibrillator (ICD); and 2) obtain estimates of effect size for QOLT compared to Heart Healthy Education on the changes in arrhythmia frequency and biomarkers of autonomic function, as well as changes in emotion, mood, and well-being across time (baseline, 3 & 9-months). It is hypothesized that the QOLT will promote improvements in autonomic function, reduced arrhythmia frequency, and improved psychological well-being.

Inclusion Criteria:

1. Adult men and women (≥18 years of age) who have received an ICD for primary or secondary prevention of sudden cardiac death. All patients will have systolic left ventricular dysfunction due to coronary disease or nonischemic cardiomyopathy. There is no requirement for time since implant;
2. Score ≥5 on the Hospital Anxiety and Depression Scale (HADS) anxiety or depression scales;
3. Able to read and write English
4. Able to commit to the 3-month QOLT/HHE program and 3 assessments over a 9-month duration.

Exclusion Criteria:

1. >5% atrial or ventricular pacing;
2. Sinus node dysfunction;
3. Persistent and permanent atrial fibrillation (AF) (h/o of paroxysmal AF will be allowed).
4. Long QT syndrome; and other channelopathies such as Brugada syndrome;
5. Hypertrophic cardiomyopathy;
6. Neurocognitive or cognitive impairments;
7. Severe psychopathology that warrants intensive treatment;
8. Participation in another research trial; and
9. Currently in psychological or psychiatric treatment.
10. Current psychotropic and cardiac medication prescriptions and usage need to be stable (i.e., no change in type or dosage) for 3-months prior to study enrollment.