Bradycardia, also known as bradyarrhythmia, is a slow heart rate, namely, a resting heart rate of under 60 beats per minute (BPM) in adults.It is a type of cardiac arrhythmia. It seldom results in symptoms until the rate drops below 50 BPM.
Bradycardia can cause dizziness, weakness, lack of energy or fainting spells.If bradycardia is caused by a medical illness, there will be additional symptoms that are specific to that illness. For example, people whose bradycardia is due to severe hypothyroidism also can have constipation, muscle cramps, weight gain (often despite poor appetite), very dry skin, hair that is thin and dry, an abnormal sensitivity to cold temperatures and other symptoms related to low levels of thyroid hormones.
An additional analysis was performed using the newer revised clinical guidelines for tachycardia (RPR greater than 90 beats/min) and bradycardia (RPR less than 50 beats/ min). By these criteria, the estimated prevalence of tachycardia among men in the normative sample is 5.2% (95% CI = 4.6–5.9), while the prevalence of bradycardia is 1.6% (95% CI = 1.2–2.0). Among adult females, the overall prevalence of tachycardia is 8.4% (95% CI = 7.6–9.2) and the prevalence of bradycardia is 0.3% (95% CI = 0.1–0.5). Overall, comparing males with females and adjusting for the effect of age, males have significantly higher odds (that is, 6.38; 95% CI = 3.05–13.36; p < 0.05) of having bradycardia and lower odds (that is, 0.59; 95% = CI 0.52–0.68; p < 0.05) of having tachycardia. Using the revised clinical criteria, a more detailed analysis of the prevalence of bradycardia and tachycardia was performed for the four adult age groups (20–39, 40–59, 60–79, and 80 and over). Among males, there are no statistically significant differences in the prevalence rates for either bradycardia or tachycardia across the four adult age groups. In contrast, there are statistically significantly differences in frequency of tachycardia across the four adult age groups for females (Satterthwaiteadjusted chi-square = p < 0.0001). The highest frequency of tachycardia is seen among females aged 20–39 (9.7%; 95% CI = 8.6–11.0), and the lowest rate is seen among females aged 60–79 (7.1%; 95% CI = 5.5–9.1). Similar to adult males, there are no statistically significant differences in the prevalence rates for bradycardia in females across the four adult age groups