Abstract

Objectives: The current article aims to identify the determinants of the baseline cardiac ejection fraction, and also the ejection fraction on dobutamine dose of 558 heart patients who underwent dobutamine stress echocardiography (DSE).

Background: Little is known about the determinants of ejection fraction with DSE.

Methods: The response ejection fraction is positive, heterogeneous, and gamma distributed, so joint generalized linear gamma model fitting is used.

Results: The baseline cardiac ejection fraction (baseEF) increases as the peak heart rate (pkhr) (P=0.0247), or systolic blood pressure (sbp) (P=0.0007), or ejection faction on dobutamine (dobEF) (P<0.001) increases. The baseEF decreases as the double product (DP) of peak heart rate and systolic blood pressure (dp) (P=0.0017), or dobutamine dose given (dose) (P=0.0255) increases. The baseEF increases of the cardiac patients with DSE who have recent angioplasty (newPTCA) (P=0.0101), or history of myocardial infraction (hxofMI) (P=0.0658), or baseline electrocardiogram diagnosis (ecg) at normal level (P=0.0555). The baseEF increases of the cardiac patients with DSE who have not resting wall motion abnormality on echocardiogram (ECDG) (restwma) (P=0.0003), or positive stress echocardiogram (posSE) (P<0.001), or history of angioplasty (hxofPTCA) (P=0.0384). On the other hand, the ejection fraction on dobutamine dose (dobEF) increases as the dp (P=0.0007), or dose (P=0.0110), or baseEF (P<0.001) increases. Also the dobEF decreases as the sbp (P=0.0012) increases. The dobEF increases of the cardiac patients with DSE who have posSE (P<0.001), or new myocardial infraction (newMI) (P=0.0054), or recent bypass surgery (newCABG) (P=0.0049). Again, the dobEF increases of the cardiac patients with DSE who have not newPTCA (P=0.0708). Also the dobEF decreases of the cardiac patients with DSE who have heavy history of smoking (hxofCig) (P=0.0261).

Conclusion: Impacts of pkhr, basal blood pressure, sbp, mbp, dobutamine dose, heart conditions, heavy smoking and others on baseEF and dobEF have been identified based on probabilistic modelling. Most of the present findings and their effects are almost new in the cardiac ejection fraction diagnosis literature.

Keywords: Cardiac ejection fraction; Cardiac parameters;Dobutamine dose; Gamma models; Heart conditions; Non-constant variance