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Patients with early diabetic heart disease demonstrate a normal myocardial response to dobutamine
Zhi You Fang1, Ofelia Najos-Valencia, Rodel Leano
1University of Queensland, Brisbane, Australia.
Insights
Diabetic cardiomyopathy shows subtle left ventricular (LV) dysfunction, but the response to stress is normal. This suggests ischemia from small-vessel disease is unlikely in early diabetic heart muscle disease.
Area of Science:
- Cardiology
- Diabetology
- Myocardial Physiology
Background:
- Diabetic cardiomyopathy is a recognized clinical and experimental condition.
- The underlying causes of diabetic cardiomyopathy remain incompletely understood.
- Investigating early signs of cardiac dysfunction in diabetes is crucial.
Purpose of the Study:
- To assess regional left ventricular (LV) response to stress using quantitative markers.
- To determine if diabetic cardiomyopathy is associated with myocardial ischemia.
- To investigate subtle LV dysfunction in diabetic patients without overt cardiac disease.
Main Methods:
- Studied 41 diabetic patients and 41 controls with normal resting LV function.
- Utilized dobutamine echocardiography to assess myocardial velocities.
- Measured peak myocardial systolic velocity (Sm) and early diastolic velocity (Em) at rest and during stress.
Main Results:
- Diabetic patients exhibited significantly lower baseline Sm compared to controls.
- Early diastolic velocity (Em) was significantly lower in diabetic patients across all stress levels.
- Both groups showed similar absolute and relative increases in Sm and Em from rest to peak stress.
Conclusions:
- Subtle left ventricular (LV) dysfunction is present in diabetic patients without apparent cardiac disease.
- The preserved response to dobutamine stress suggests ischemia is not a primary driver of early diabetic heart muscle disease.
- Further research is needed to elucidate the mechanisms of diabetic cardiomyopathy.
Objectives:
We sought to use quantitative markers of the regional left ventricular (LV) response to stress to infer whether diabetic cardiomyopathy is associated with ischemia.
Background:
Diabetic cardiomyopathy has been identified in clinical and experimental studies, but its cause remains unclear.
Methods:
We studied 41 diabetic patients with normal resting LV function and a normal dobutamine echo and 41 control subjects with a low probability of coronary disease. Peak myocardial systolic velocity (Sm) and early diastolic velocity (Em) in each segment were averaged, and mean Sm and Em were compared between diabetic patients and controls and among different stages of dobutamine stress.
Results:
Both Sm and Em progressively increased from rest to peak dobutamine stress. In the diabetic group, Sm was significantly lower than in control subjects at baseline (4.2 +/- 0.9 cm/s vs. 4.7 +/- 0.9 cm/s, p = 0.012). However, Sm at a low dose (6.0 +/- 1.3), before peak (8.4 +/- 1.8), and at peak stress (8.9 +/- 1.8) in diabetic patients was not significantly different from that of controls (6.3 +/- 1.4, 8.9 +/- 1.6, and 9.6 +/- 2.1 cm/s, respectively). The Em (cm/s) in the diabetic group (rest: 4.2 +/- 1.2; low dose: 5.0 +/- 1.4; pre-peak: 5.3 +/- 1.1; peak: 5.9 +/- 1.5) was significantly lower than that of controls (rest: 5.8 +/- 1.5; low dose: 6.6 +/- 1.5; pre-peak: 6.9 +/- 1.3; peak: 7.3 +/- 1.7; all p < 0.001). However, the absolute and relative increases in Sm or Em from rest to peak stress were similar in diabetic and control groups.
Conclusions:
Subtle LV dysfunction is present in diabetic patients without overt cardiac disease. The normal response to stress suggests that ischemia due to small-vessel disease may not be important in early diabetic heart muscle disease.