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A nursing school clinic in the US.
133 patients (73% men) who had survived “out of hospital” ventricular fibrillation or asystole (confirmed by electrocardiography). Exclusion criteria included coronary artery bypass surgery or other vascular procedures in the previous 6 months, diabetes, moderate to severe anoxic encephalopathy, and other life threatening comorbid conditions. More than 96% of patients completed the treatment period, and the mortality status of 97% of patients was known at 2 years.
After stratification by sex, patients were allocated to 11 individual 90 minute sessions of psychosocial therapy (n=67) or usual care (n=66). Psychosocial therapy was given by 1 of 2 cardiovascular nurses and consisted of (1) physiological relaxation with computerised feedback training focused on altering autonomic tone; (2) cognitive behavioural therapy for improving self management and coping strategies for depression, anxiety, and anger; and (3) health education about cardiovascular risk factors. The usual care group also received a health education class about cardiovascular risk factor modification.
Main outcome measures
Cardiovascular mortality (death from arrhythmia, stroke, myocardial infarction, or congestive heart failure). Secondary outcomes included all cause mortality.
By 2 years, 3 patients in the psychosocial group had died (1 cardiovascular death) and 8 in the usual care group died (7 cardiovascular deaths). The risk of cardiovascular death was lower in the psychosocial therapy group than in the usual care group (p=0.03) (table⇓). The risk reduction remained statistically significant after adjusting for other predictors of mortality: depression, hypertension, previous myocardial infarction, low heart rate variability, congestive heart failure, and ventricular ectopic beats (>10 beats/h on Holter monitor). The groups did not differ for all cause mortality at 2 years.
In patients who had survived “out of hospital” sudden cardiac arrest, psychosocial therapy reduced the risk of cardiovascular death at 2 years.
Psychosocial therapy has long been considered to be a potentially valuable tool in providing quality care to patients with coronary artery disease (CAD) in the aftermath of a myocardial infarction. The study by Cowan et al provides further evidence of this value, one that persists 2 years after an “out of hospital” sudden cardiac arrest. Although previous study findings suggest the benefits of cognitive behavioural therapies in reducing cardiovascular death,1 this study is noteworthy in reporting an 86% risk reduction in 129 patients, a reduction that persisted after controlling for important confounders.
It is unclear, however, why psychosocial therapy is so effective in reducing cardiovascular death in these patients. The overwhelming evidence is that such patients often experience depression, anxiety, and anger. Although negative mood may seem an inevitable consequence of CAD, it may also precipitate sudden cardiac arrest. The authors also make a good case for the use of biofeedback to restore autonomic nervous function and increase heart rate variability (HRV).
This study fails to indicate, however, which of the 3 components, if any, contributed to the success of this intervention. No statistically significant changes were observed in HRV (except in patients with low baseline levels) or mood (except for a marginal effect on depression). The reduction in breathing rate disappeared at 6 months. Hence, no clear evidence exists of a causal mechanism involving either physiological relaxation or cognitive behavioural therapy.
Perhaps the answer lies in the increased attention given to the 67 patients in the intervention group of this study. These patients attended 11 individual sessions over a 5–6 week period, each session lasting 90 minutes. In contrast, no information is provided on the content of the “conventional treatment” of the 66 control patients and whether this treatment included a comparable level of attention or involvement with healthcare personnel. The increased interaction between patients and nursing staff may have contributed more to the dramatic reduction in cardiovascular death than the context of this interaction (ie, the psychosocial therapy), a phenomenon known as the Hawthorne Effect.
Further details about the psychosocial therapy intervention
This component had 4 strategies for training patients to cognitively change autonomic nervous system responses:
Deep abdominal breathing
Progressive muscle relaxation
Each strategy included computerised biofeedback training with the recording of continuous breathing, heart rate, blood pressure, and trapezius electromyograph. A detailed description of the protocol and measurement of heart rate variability was previously published.
Cognitive behavioural therapy
Cognitive behavioural therapy was based on standard practices for self management of depression, anxiety, and anger (using Beck Cognitive Therapy and Lazarus theory of stress appraisal and coping).
Health education consisted of a 90 minute class on cardiovascular risk factor modification, and this component was given to both groups.
(1) Cowan MJ, Kogan H, Burr R, et al. Power spectral analysis of heart rate variability after biofeedback training. J Electrocardiol 1990;23(suppl):85�94.
(2) Cowan MJ, Pike K, Burr RL. Effects of gender and age on heart rate variability in healthy individuals and in persons after sudden cardiac arrest. J Electrocardiol 1994;27(Suppl):1�9.
(3) US Department of Health and Human Services. Depression in primary care: treatment of major depression. Washington, DC: US Department of Health and Human Services, 1993. AHCPR Pub No 93-0551. http://text.nlm.nih.gov/ahcpr/dep/www/dep1ctxt.html
(4) Beck AT. Cognitive therapy and the emotional disorders. New York: International Universities Press, 1976.
(5) Lazarus RS, Folkman S. Stress, appraisal, and coping. New York: Springer Publishing, 1984.
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