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Aim and Introduction
TIMI frame count was first described by Gibson et al., in order to generate a standardized method to measure the coronary blood flow. Substantial number of studies demonstrated that TIMI frame count is associated with endothelial dysfunction and coronary slow flow. Arterial blood pressure (BP) normally shows physiological diurnal fluctuations. Normally more than 10 % decrease is expected in nocturnal blood pressure. If the decline is > 10 % it is called dipper and if it's < 10 % it's called as non-dipper hypertension. The aim of this study was to evaluate the differences in TIMI frame counts between patients with non-dipper and dipper hypertension, which have normal coronary angiograms.
Thirty dipper and thirty non-dipper hypertension patients with angiographically documented normal coronary arteries were recruited for this study. Socio-demographic and clinical data were collected in addition to the body mass index. TIMI frame counts were calculated by the Gibson et al. method. A series of independent-t tests and chi-square were conducted in order to analyse group differences.
Accordingly, there were no differences between the groups in terms of gender, age, smoking and alcohol consumption. TIMI frame counts of the three coronary arteries and the average TIMI frame counts were found significantly lower in the dipper hypertension group as compared to non-dipper group (See table 1). BMI of the non-dipper hypertension patient group (25.47±2.92) was significantly (p=0.027) higher than the dipper hypertension group (23.79±2.81). Lastly, non-dipper hypertension group exerted significantly higher heart rate (72.70±4.86; p=0.001) as opposed to the dipper hypertension group (66.57±4.92).
To the best of our knowledge, this is the first study comparing the differences in TIMI frame counts between dipper and non-dipper hypertension patients with normal coronary angiograms. The main finding of this study is that, the average TIMI frame count and TIMI frame counts of the three coronary arteries is higher in the group with non-dipper hypertension compared to the group with dipper hypertension. Considering the well-replicated findings on the endotelial dysfunction and coronary slow flow presented in non-dipper hypertensive patients, utilizing TIMI frame counts in the clinical practice could be an efficient, objective and repeatable method to indirectly evaluate the microvascular dysfunction in these patients.
|Dipper Group||Non-Dipper Group||p|
|RCA TIMI frame count||16.83±3.70||21.63±3.44||<0.001|
|Cx TIMI frame count||21.28±3.52||25.65±3.61||<0.001|
|LAD TIMI frame count||34.20±2.80||37.05±3.30||0.001|
|LAD Adjusted TIMI frame count||20.05±1.63||21.74±1.95||0.001|
|Mean TIMI frame count||19.31±2.31||22.94±2.61||<0.001|
RCA: Right coronary artery, Cx: Circumflex artery, LAD: Left anterior descending artery