New onset third degree or complete heart block (CHB) is a medical emergency and usually requires permanent pacemaker. CHB can be caused by cardiac ischemia or non-ischemic conditions such as infiltrative diseases or fibrosis. The purpose of this study was to analyze the clinical characteristics associated with ischemic versus non ischemic causes of complete heart block.
Methods:
For this analysis, Institutional Review Broad approval was granted by the Cleveland Clinic Health System. 216 patients with CHB presenting to Fairview Hospital between January 2014 and June 2016 were initially identified using the International Classification of Disease (ICD) codes at discharge. Only the patients with a new diagnosis of complete heart block (CHB) were included. This led to the exclusion of 153 patients. Patients were characterized as non-ischemic and ischemic groups based on cardiac marker elevation, EKG changes and/or cardiac catheterization findings. In all the patients data was collected including demographics such as age, gender, ethnicity and body mass index; pre-existing co-morbidities such as hypertension, chronic kidney disease, diabetes mellitus, previous coronary artery disease, history of cancer; use of nodal blocking agents, electrolyte abnormalities on admission, echocardiographic parameters such as ejection fraction (EF), right ventricular systolic pressure (RVSP), left ventricular end diastolic and systolic volumes (LVEDV and LVESV, respectively). Categorical variables were analyzed using chi-square and continuous variables using ANOVA.
Results:
Out of 63 patients (n=63), 49 had non-ischemic and 14 had ischemic CHB. There was no statistically significant difference between the two groups in terms of gender, pre-existing comorbidities, or smoking status. The mean age was 67 years (95% CI, 60.55-74.73) in the ischemic CHB and 75 years (95% CI, 71.52- 78.80) in the non-ischemic heart block, p = 0.53. Patients with Ischemic CHB had a lower mean EF of 49.6% (95% CI, 42.04%-57.23%) compared to 57.42% in non-ischemic CHB patients (95% CI, 53.97%-60.87%), p= 0.048. RVSP was 33.12 (95% CI, 21.7-44.54) in ischemic CHB versus 41.72 (95% CI, 36.48-46.97) in non-ischemic CHB (p= 0.172).
Conclusions:
The clinical characteristics of ischemic and non-ischemic CHB patients did not vary significantly with the exception of ejection fraction. Also patients with non-ischemic CHB were relatively older. Further studies are required to understand the long term outcomes of patients with CHB.