Characteristics of Heart Rate Variability in War Veterans with Post-Traumatic Stress Disorder after Myocardial Infarction

Military Medicine, Nov 2007 by Lakusic, Nenad, Fuckar, Krunoslav, Mahovic, Darija, Cerovec, Dusko, Majsec, Marcel, Stancin, Nevenka

Objective: The goal of the study was to evaluate differences in heart rate variability (HRV) among post-myocardial infarction (MI) patients, depending on their participation in the Croatian war and on established diagnoses of post-traumatic stress disorder (PTSD). Methods: The study included 34 male war veterans with diagnosed PTSD who had suffered a first MI and 34 age-matched post-MI patients without PTSD. Cardiac autonomic balance was evaluated through HRV analysis. Results: There were no differences in the mean R-R interval or overall HRV between the analyzed groups. Post-MI patients with PTSD had lower values for the square root of the mean of squared successive differences in R-R intervals (p = 0.02), the percentage of R-R intervals that were ≥50 milliseconds different from the previous interval (p = 0.03), and the high-frequency component (p = 0.03) but had higher values for the low-frequency component (p = 0.01) and the low-frequency/high-frequency ratio (p = 0.02), compared with post-MI patients without PTSD. Conclusion: Post-MI patients with PTSD have higher sympathetic and lower parasympathetic heart rate modulation activity, compared with patients with MI and no PTSD.

Introduction

During the war years in Croatia, the incidence of myocardial infarction (MI) was significantiy higher than in the years preceding the war. The majority of patients were male patients of younger age, compared with the prewar years.1 The effects of exposure to war stress on physical and mental health have been extensively examined and well documented. Post-traumatic stress disorder (PTSD) has been identified as the most frequent psychopathological consequence of exposure to stressors related to combat.2 PTSD as a diagnostic entity is characterized by four groups of symptoms. It is the only psychiatric diagnostic category in which a person has been exposed to extreme stress and felt helpless, terrified, or frightened (group A symptoms). Group B consists of symptoms associated with continued reexperience of the traumatic event. Group C and D symptoms include a few symptoms of avoidance and increased arousal.3 Among Croatian war veterans, depression is one of the most prevalent diagnoses and the most common disorder comorbid with PTSD.4

Heart rate variability (HRV) is recognized as an indicator of autonomic nervous system activity, and changes in HRV reflect a level of vagosympathetic imbalance. Autonomic imbalance (i.e., predomination of sympathetic activity over vagal activity) leads to lowering of HRV. There are various conditions that can lower HRV, such as acute MI, stroke, and cardiac failure.56 Decreased HRV is found to be a risk factor for the onset of malignant arrhythmias and sudden death, for all-cause cardiac death, and even for allcause death.7 A previous study found lower HRV in patients with PTSD, compared with control subjects..8 The goal of this study was to evaluate differences in HRV among patients who had suffered from MI, depending on their participation in the Croatian war and an established diagnosis of PTSD.

Methods

This prospective study included 34 consecutive male patients who were Croatian war veterans with an established diagnosis of PTSD and had suffered a first MI within 3 months after the acute phase of the disease (group 1; mean age, 49 ± 8years) and 34 age-matched male subjects who had suffered a MI but did not actively participate in the war operations in Croatia and had no PTSD (group 2). All patients participated in the second phase of a cardiac rehabilitation program in the period of 2002-2005. Exclusion criteria were an unstable phase of PTSD (i.e., exacerbation of symptoms that would demand active psychiatric treatment), atrial fibrillation, sick sinus syndrome, second- or thirddegree atrioventricular block, previous MI, coronary artery bypass grafting, diabetes mellitus, heart failure, cardiopulmonary resuscitation during the acute phase of the MI, or some other acute disease.

There were no significant differences between the groups with respect to risk factors for coronary artery disease, anatomical localization, or treatment options for MI during the acute phase of the disease (Table I). Furthermore, there were no significant differences between the groups with respect to medications received during rehabilitation (Table II). The only exception was a higher rate of anxiolytic or antidepressant agent intake in group 1, compared with group 2 (p

Cardiac autonomic balance was evaluated through HRV analysis. All HRV variables were measured through a 22.6-hour period (range, 21-24 hours). Ambulatory electrocardiographic recordings were made with three-channel Medilog FD3 digital Holter recorders (Oxford Instruments, Abingdon, U.K.) with 1,024-Hz resolution. HRV was analyzed by computer and proofread manually. A commercial system (Oxford Instruments; with Medilog Holter Management System Excel 2 software, version 7.1) was used. Algorithms for arrhythmia analysis gave a label to each QRS complex. The operator cleaned all recordings to be artifact-free, reviewed beats, and modified them if needed, under cardiologist supervision. Only recordings with