Shemaila Saleem, Qazi Waheed Ullah, Syed Muhammad Imran Majeed.
Comparison of Heart Rate Variability in Patients after Acute Myocardial Infarction and Healthy Individuals.
Ann Pak Inst Med Sci Jan ;7(4):191-5.

Objective: To compare heart rate variability in patients of acute myocardial with that of healthy individuals and to establish correlation between time and frequency domain indices of heart rate variability in patients with AMI and healthy individuals. Study Design: Non-interventional descriptive study. Place and Duration: Armed Forces Institute of Cardiology (AFIC)/National Institute of Heart Diseases(NIHD), Rawalpindi over six months. Materials and Methods: We studied 45 patients of AMI and same number of age and sex matched normal healthy volunteers. Their 24-hour holter recordings within 48h of acute myocardial infarction were analyzed for HRV in time and frequency domains. Results: The time domain indices; SDNN (healthy volunteers=133±35ms vs. AMI=75±29ms), SDANN (healthy volunteers=118±34ms vs. AMI=65±28ms), SDNNi (healthy volunteers=59±18ms vs. AMI=35±14ms), rMSSD (healthy volunteers=40±17ms vs. AMI=28±13ms) and pNN50 (healthy volunteers=13±9% vs. AMI=6±11%) were significantly decreased (P less than 0.001) in patients with AMI when compared with healthy volunteers. Comparison of frequency domain indices; TP (healthy volunteers=3525±2671ms2 vs. AMI=1296±1178ms2), VLF (healthy volunteers=2485±2201ms2 vs. AMI=902±928ms2), LF (healthy volunteers=695±391ms2 vs. AMI=246±251ms2), HF (healthy volunteers=315±259ms2 vs. AMI=100±96ms2) between healthy volunteers and patients after myocardial infarction revealed a significant decline (P less than 0.001) in the parameters of patients. SDNNi was significantly correlated with power and VLF in normal healthy volunteers (power; r=0.92, VLF; r= 0.89) as well as in patients with AMI (power; r=0.85, VLF; r= 0.78). Conclusion: Time domain and frequency domain indices of HRV are significantly affected by early phase of AMI. This indicates HRV assessment after AMI may be useful in noninvasive risk stratification. It is suggested that mortality should be verified after follow-up studies of AMI. Time and frequency domain indices are significantly correlated.

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