Association between PTSD and Impedance Cardiogram‐based contractility metrics during trauma recall: A controlled twin study

Abstract

Post-traumatic stress disorder (PTSD) is an independent risk factor for incident heart failure, but the underlying cardiac mechanisms remained elusive.Impedance cardiography (ICG), especially when measured during stress, can help understand the underlying psychophysiological pathways linking PTSD with heart failure. We investigated the association between PTSD and ICG-based contractility metrics (pre-ejection period (PEP) and Heather index (HI)) using a controlled twin study design with a laboratory-based traumatic reminder stressor.PTSD status was assessed using structured clinical interviews. We acquired synchronized electrocardiograms and ICG data while playing personalized-trauma scripts. Using linear mixed-effects models, we examined twins as individuals and within PTSD-discordant pairs. We studied 137 male veterans (48 pairs, 41 unpaired singles) from Vietnam War Era with a mean (standard deviation) age of 68.5(2.5) years. HI during trauma stress was lower in the PTSD vs. non-PTSD individuals (7.2 vs. 9.3 [ohm/s 2 ], p = .003). PEP reactivity (trauma minus neutral) was also more negative in PTSD vs. non-PTSD individuals (−7.4 vs. −2.0 [ms], p = .009). The HI and PEP associations with PTSD persisted for adjusted models during trauma and reactivity, respectively. For within-pair analysis of eight PTSD-discordant twin pairs (out of 48 pairs), PTSD was associated with lower HI in neutral, trauma, and reactivity, whereas no association was found between PTSD and PEP. PTSD was associated with reduced HI and PEP, especially with

Impedance cardiogram based exploration of cardiac mechanisms in post‐traumatic stress disorder during trauma recall

“…Adding this category of features slightly changed the selected features. These results are in line with our earlier findings, where a robust association was found between PTSD and trauma HI or reactivity PEP in presence of confounding SDMP factors (Sheikh et al., 2023).…”

“…Figure 7 middle right panel indicates that the VIs of PTSD participants were typically less than that of non‐PTSD participants indicating a lower blood velocity and a weakened left ventricular contractile force for the trauma phase. PEP: The reactivity PEP with feature scores of 1.0 and 0.91, respectively with and without the SDMP feature set, was identified as an essential parameter for PTSD versus non‐PTSD identification. These results confirm our earlier findings that we showed a robust association between PEP and PTSD using linear mixed‐effect models (Sheikh et al., 2023). It is well‐known that PEP is inversely related to myocardial contractility and has been validated as an index of cardiac sympathetic beta‐adrenergic activity (Cacioppo et al., 1994; Mezzacappa et al., 1999; Newlin & Levenson, 1979).…”

“…However, one should note that an increased sympathetic activation, as indicated by decrease in PEP, would normally increase the left ventricular contractility (Gordan et al., 2015). HI: The trauma HI with feature scores of 0.94 and 0.97, respectively, with and without the SDMP feature set, was identified as a differentiating factor for PTSD from non‐PTSD cases, confirming our earlier findings regarding the robust association between HI and PTSD using linear mixed‐effect models (Sheikh et al., 2023). HI is an alternate parameter for measuring blood acceleration through the aorta.…”

“…To the best of our knowledge, our earlier work is the only ICG-based study in which we showed a robust association between two parameters (i.e., PEP and Heather index (HI)) and PTSD during trauma recall using linear mixed-effects models (Sheikh et al, 2023). A linear mixed-effects model is a linear statistical model that is equipped for the analysis of both fixed and random effects in the data.…”

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“…Researchers are now investigating candidate mechanisms. In one recent study, individuals diagnosed with PTSD were found to exhibit decreased cardiac contractility despite concurrently increased sympathetic tone as indexed by preejection period 13 . In rats exposed to predator stress, Rorabaugh and colleagues observed hypersensitivity to cardiac ischemia [14][15][16][17][18] .…”