To test associations between heart rate variability (HRV), depressed mood, and positive affect in patients with suspected coronary artery disease (CAD). Depression is associated with impaired HRV post acute cardiac events, but evidence in patients with stable coronary artery disease (CAD) is inconsistent.
Seventy-six patients (52 men, 24 women; mean age = 61.1 years) being investigated for suspected CAD on the basis of symptomatology and positive noninvasive tests, completed 24-hour electrocardiograms. The Beck Depression Inventory (BDI) was administered, and positive and depressed affect was measured over the study period with the Day Reconstruction Method (DRM). A total of 46 (60.5%) patients were later found to have definite CAD. HRV was analyzed, using spectral analysis.
Typical diurnal profiles of HRV were observed, with greater normalized high frequency (HF) and lower normalized low frequency (LF) power in the night compared with the day. BDI depression scores were not consistently associated with HRV. But positive affect was associated with greater normalized HF power (p = .039) and reduced normalized LF power (p = .007) independently of age, gender, medication with β blockers, CAD status, body mass index, smoking, and habitual physical activity level. In patients with definite CAD, depressed affect assessed using the DRM was associated with reduced normalized HF power and heightened normalized LF power (p = .007) independently of covariates.
Relationships between depression and HRV in patients with CAD may depend on affective experience over the monitoring period. Enhanced parasympathetic cardiac control may be a process through which positive affect protects against cardiovascular disease.
BDI = Beck Depression Inventory;
CAD = coronary artery disease;
CHD = coronary heart disease;
DRM = Day Reconstruction Method;
ENRICHD = Enhancing Recovery in Coronary Heart Disease;
HRV = heart rate variability;
HF = high frequency;
LF = low frequency;
MI = myocardial infarction;
pNN50 = the number of pairs of adjacent NN intervals differing by >50 ms, divided by the total number of NN intervals;
RMSSD = square root of the mean of the sum of the squares of successive NN differences;
VLF = very low frequency.