The effect of left ventricular diastolic function on the secretion of B-type natriuretic peptide at rest and directly after exercise test in asymptomatic patients with diabetes or after myocardial infarction with preserved left ventricular systolic functi.

BACKGROUND

Clinical evaluation of patients with diabetes or after myocardial infarction (MI) with preserved left ventricular (LV) systolic function is not very precise in isolating patients at particularly high risk of developing manifest cardiac failure and associated cardiovascular incident. Early diagnosis of LV diastolic dysfunction is essential because implementation of the appropriate treatment can positively affect the course of the disease.

AIM

To assess the impact of LV diastolic function on B-type natriuretic peptide (BNP) concentration at rest and immediately after exercise test, and to search for the relationship between LV diastolic function and BNP secretion, tolerance, and duration of exercise in the studied groups of patients.

METHODS

Ninety-nine consecutive patients were qualified for the study: in Group 1 - patients with type 2 diabetes without a history of MI, and in Group 2 - patients after MI with preserved LV systolic function (ejection fraction ≥ 40%), without diabetes. The studied patients had echocardiography with LV systolic and diastolic function evaluation, an electrocardiographic exercise test and blood sampling for BNP determination before and immediately after exercise test.

RESULTS

The study included 99 patients aged 40-75 years (60 patients after MI and 39 patients with diabetes). The study group included 62 patients who were diagnosed with diastolic dysfunction. Diastolic dysfunction occurred in 41 (68.4%) patients in the group after MI, and in 21 (53.8%) patients in the group with diabetes, severe disorders in the form of pseudonormal and restrictive mitral valve inflow occurred in 13 (21.7%) and five (12.8%), respectively. The average BNP concentration in patients with severe diastolic dysfunction at rest was 188.3 vs. 25.2 pg/mL in patients with normal diastolic function (p < 0.001). In all patients with severe diastolic dysfunction BNP after exercise was 285.2 vs. 37.5 pg/mL in patients with normal diastolic function, and the increase in BNP during exercise was 96.9 vs. 12.4 pg/mL, respectively. Duration of exercise and exercise tolerance in patients with normal diastolic function was better in comparison with the studied patients with disturbed diastolic function, but did not reach statistical significance.

CONCLUSIONS

The BNP initial concentration and its value immediately after exercise were significantly higher in subjects with severe diastolic disorders than those in subjects with normal LV diastolic function and in subjects with impaired LV relaxation.