ABC | Volume 112, Nº1, January 2019

Original Article Eyuboglu & Akdeniz Prehypertension and fragmented QRS Arq Bras Cardiol. 2019; 112(1):59-64 1. Chobanian AV, Bakris GL, Black HR, Cushman WC, Green LA, Izzo JL Jr, et al. Seventh report of the joint national committee on prevention, detection, evaluation, and treatment of high blood pressure. Hypertension. 2003;42(6):1206–52. 2. Wang S, Wu H, Zhang Q, Xu J, Fan Y. Impact of baseline prehypertension on cardiovascular events and all-cause mortality in the general population: a meta-analysis of prospective cohort studies. Int J Cardiol 2013;168(5):4857–60 3. Verdecchia P. Prognostic value of ambulatory blood pressure : current evidence and clinical implications. Hypertension. 2000;35(3):844-51. 4. O’Brien E, Parati G, Stergiou G, Asmar R, Beilin L, Bilo G, et al. European Society of Hypertension Working Group on Blood Pressure Monitoring. European Society of Hypertension position paper on ambulatory blood pressure monitoring. J Hypertens. 2013;31(9):1731–68. 5. Das MK, Saha C, El Masry H, Peng J, Dandamudi G, Mahenthiran J, et al. Fragmented QRS on a 12-lead ECG: a predictor of mortality and cardiac events in patients with coronary artery disease. Heart Rhythm. 2007;4(11):1385-92. 6. Jain R, Singh R, Yamini S, Das MK. Fragmented ECG as a risk marker in cardiovascular diseases. Curr Cardiol Rev. 2014;10(3):277-86. References hypertensive patients. Since the presence of fQRS on ECG is an important predictor of fibrosis and fibrotic burden within myocardium, the results of our study indicate a higher fibrotic burden in prehypertensive non-dippers compared to normotensives. The possible underlying mechanism for the association between fQRS and non‑dipper blood pressure pattern in prehypertensives might be similar in hypertensive patients. Autonomic dysfunction-related increased sympathetic activity during nighttime, and chronic-continuous pressure overload related collagen fibers and connective tissue matrix accumulation within the myocardium might play the key roles for higher fibrotic burden and fibrosis in these patients. 17-19 Non-dipping hypertension is a prognostic factor, and increased nighttime blood pressure levels indicate worse adverse cardiovascular outcomes compared to dipper patterns. 4,20 Hence, definition of non-dippers is clinically important. In addition to being the precursor of hypertension, prehypertension includes a variety of patients who are at high risk for adverse cardiovascular events. Therefore, our results suggest that fQRS may be useful in defining the deteriorated circadian blood pressure variability which indicates high-risk prehypertensives. Another aspect of our study is the importance of using 24‑hour ABPM for detailed evaluation of blood pressure and final blood pressure pattern diagnosis. It is known that blood pressure patterns vary between ABPM and office records. 4,21 Similarly, our study revealed that an important proportion of prehypertensive patients were not prehypertensive after 24-hour ABPM results. Since 24‑hour ABPM is the gold standard for evaluation and diagnosis of hypertension, our study includes real prehypertensives. Our study has some limitations. First, the study sample size is relatively small; however, the detection of prehypertensive patients is not an easy procedure in clinical practice. Second, our study included only newly diagnosed prehypertensive patients. Third, definition of prehypertension based on ABPM records is not clear. Hence, we designated patients with non-hypertensive elevated blood pressure as prehypertensives. Finally, lack of data regarding confirmation of fibrosis within myocardium by magnetic resonance imaging is another limitation. Conclusions Fibrosis within myocardium is an important predictor of adverse cardiovascular events in patients with elevated blood pressure. fQRS is a simple and easily detectable ECG finding that indicates fibrosis within myocardium. This study revealed an important relationship between fQRS and non-dipper status in prehypertensive patients. We found that non-dipper prehypertensives have significantly higher frequency of fQRS compared to normotensives, and fQRS is an independent predictor of non-dipping in prehypertension. Our results suggest that fQRS may be useful in identifying high-risk prehypertensive patients before the development of hypertension. This identification may be helpful in terms of adequate prevention for future cardiovascular events. Future studies are necessary to demonstrate the prognostic value of fQRS in prehypertensive patients and to understand whether a more aggressive prehypertension treatment could normalize the ECG findings. Author contributions Conception and design of the research: Eyuboglu M; acquisition of data, analysis and interpretation of the data and critical revision of the manuscript for intellectual content: Eyuboglu M, Akdeniz B; statistical analysis: Eyuboglu M; writing of the manuscript: Eyuboglu M. Potential Conflict of Interest No potential conflict of interest relevant to this article was reported. Sources of Funding There were no external funding sources for this study. Study Association This study is not associatedwith any thesis or dissertationwork. Ethics approval and consent to participate This article does not contain any studies with human participants or animals performed by any of the authors. 63