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Myocardial Infarction and Functional Outcome Assessment in Pigs
Published on: April 25, 2014
Relationships between heart rate variability, functional capacity, and left ventricular function following myocardial
J V Monmeneu1, F J Chorro, V Bodí
1Cardiology Service, University Clinic Hospital, Valencia, Spain.
Insights
Heart rate variability decreases after myocardial infarction, linked to reduced functional capacity and ejection fraction. However, HRV recovers in most survivors within six months, especially those with lower initial ejection fraction.
Area of Science:
- Cardiology
- Physiology
- Medical Research
Background:
- Heart rate (HR) variability's prognostic significance post-myocardial infarction (MI) is not fully understood.
- Key prognostic markers like ejection fraction (EF) and functional capacity require further investigation in relation to HR variability.
Purpose of the Study:
- To prospectively assess early post-MI changes in HR variability.
- To evaluate the evolution of HR variability over six months.
- To determine relationships between HR variability, functional capacity, left ventricular function, and infarct-related artery status.
Main Methods:
- Prospective study of 42 anterior MI patients.
- Analysis of HR variability using the complex demodulation method.
- Assessment of functional capacity via exercise testing and left ventricular function via cardiac catheterization.
Main Results:
- Early HR variability correlated with functional capacity (METS, %deltaHR, HR range) and EF.
- HR variability parameters showed significant recovery at six months post-MI.
- Recovery of HR variability was more pronounced in patients with lower baseline EF.
Conclusions:
- Reduced HR variability post-MI is associated with diminished functional capacity and altered EF.
- HR variability demonstrates recovery in surviving patients within six months.
- HR variability is a dynamic marker of recovery after myocardial infarction.
Background:
Relationships between heart rate (HR) variability and different prognostic markers such as ejection fraction, functional capacity, and patency of the infarct-related artery, as well as the comparison of their time courses are not fully elucidated.
Hypothesis:
The aim of study was to assess prospectively the early postinfarction changes in HR variability and its evolution over a period of 6 months: the relationships between HR variability and functional capacity in exercise testing; left ventricular function in cardiac catheterization: status of the infarct-related artery; and the comparison of their time courses.
Methods:
In 42 patients with anterior myocardial infarction, a study was made of the early changes in HR variability analyzed by the complex demodulation method, its evolution over a period of 6 months. and the relationships between HR variability and (1) functional capacity in exercise testing, (2) left ventricular function in cardiac catheterization, and (3) status of the infarct-related artery.
Results:
At 1 week HR variability parameters correlated directly with functional capacity indicators such as METS, percent change in HR from rest to peak exercise (%deltaHR), difference between initial and peak HR (HR range), percent peak theoretical HR (% peak HR), left ventricular ejection fraction (EF), and, inversely, with end-systolic volume (ESV). Stepwise multiple regression analysis to establish HR variability parameters (recorded at 1 week) as related to functional capacity and left ventricular function at 1 week and 6 months postinfarction established the following variables: (1) At 1 week: standard deviation (SD) of the RR cycles in relation to %deltaHR (r = 0.60, p <0.0001), HR range (r = 0.43, p < 0.01), and EF (r = 0.79, p < 0.0001). (2) At 6 months, the sole accepted HR variability parameter was the SD in relation to %deltaHR (r = 0.38, p < 0.05) and HR range (r = 0.45, p < 0.01). No variability parameter was accepted in relation to METS, % peak HR, or ESV. Relationship between EF or ESV and HR variability parameters was not significant when both were evaluated at 6 months. At that time, there was a significant increase in all HR variability parameters among all surviving patients (n = 39), with the exception of the LF/HF ratio and mean RR cycle. The percent increase in HR variability between the first week and 6 months was greater among those patients with the lowest basal EF. No relation was established between HR variability and patency of the infarct-related artery.
Conclusion:
The decrease in HR variability observed following myocardial infarction is associated with a diminished functional capacity and an increased alteration of the EF. This does not affect the recovery of HR variability, which was observed in all surviving patients.
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