Methods and progress in the study.
A population study was selected among the study participant's Coronary Heart Disease Study, in which from 1966 to 1972 was included 10,957 persons aged 30 to 59 years from different regions of Finland. All participants, in addition to clinical examination, performed the measurement of body mass index, blood cholesterol was determined and recorded by standard ECG. All participants completed a questionnaire about lifestyle, established disease and taking medications. All ECGs were re-analyzed for SRRZH. Not subject to interpretation found only 93 ECGs.
Analysis of the ECG recorded at 50 mm / s, conducted by five doctors. Diagnosis SRRZH in the lower (II, III, aVF) and lateral (I, aVL, V4-V6) leads placed during the second revision of the ECG by a consensus of researchers. SRRZH divided by the degree of recovery points of J (≥ 0,1 mV or> 0. 2mV )and form connections of the QRS complex with segment ST (in the form of notches on the knee of S-wave, or a smooth transition). In addition, the criteria Sokolov - Lyons determined left ventricular hypertrophy (LVH), according to the formula Bazetta - corrected interval QT. In some individuals to re-register the ECG was carried out in 1973-1976 years. The primary end point of the study was death from cardiac causes, secondary endpoints - death from any cause and death from arrhythmia before the end of 2007, deaths and its cause is established according to national statistical databases. Death from arrhythmia approved by an independent committee of cardiologists, un informed about ECG data, the analysis of death certificates and hospital medical records. Relationship between SRRZH and clinical outcome was determined in the proportional hazard's model of Cox with correction for sex, age, systolic blood pressure, body mass index, heart rate (HR), smoking, left ventricular hypertrophy and signs of coronary heart disease (CHD) on the ECG with Minnesota code. Results. Study population was 10 864 people (average age - 44 ±8 years, men - 52,4%). SRRZH of them was found in 630 subjects (5.8%). In the lower leads SRRZH detected in 3.5%of cases (384participants, men - 70%)in the lateral leads - in 2, 4% of cases (262 participants, men - 58%)in the lower and lateral leads - to 01% of cases (16 participants). Elevation point t J> 0,2 mV were observed in 36 participants (0.3%) in the bottom leads and have 31participants (0.3%) in lateral ECG leads. Of 542 subjects with SRRZH on the initial electrocardiogram during repeated ECG recording (on average- after 5years) it was preserved in 443 (81,7%).
Participants with lower SRRZH leads in comparison with persons without SRRZH were more often men; smokers had a lower heart rate and body mass index, a shorter interval QT, but most of QRS duration and more frequent signs of CHD. In the presence of SRRZH in lateral leads more often showed signs of LVH.
During the observation period (30 ± 11 years) died 6133 study participants (56.5%). Deaths from cardiac causes accounted for 32.1% of all deaths. Of these, 40.4% of cases were considered sudden death from arrhythmia. In multivariate analysis of a person with a lower SRRZH lead had an increased risk of death from cardiac causes (corrected relative risk [RR] - 1.28, 95% CI 1,04-1,59, p = 0.03) and from arrhythmia ( RR - 1.43; 1,06-1,94, p = 0.03) but not total mortality (RR - 1.10; 0,97-1,26, p = 0.15). Among participants with elevation point J> 0, 2mV in the lower leads marked increase in risk of death from any cause (RR- 1.54, p = 0.03), from cardiac causes (RR- 2.98, p <0,001) and of arrhythmia (OR - 2.92, p = 0.01). Survival curves of these parties and people without SRRZH began to separate after about 15 years and continued to diverge in the future. Almost half (47.2%) participants with the elevation point of J> 0, 2mV in the lower leads died from cardiac causes, while this cause of death was noted only one in five subjects (17.2%) without SRRZH.
Prognostic value SRRZH in lateral leads was at the border level of statistical significance for mortality from heart failure and any cause, but was unreliable for predicting death from arrhythmia. A secondary analysis of the risk of death from cardiac causes was higher in patients with long intervals of QT ≥ 440 ms in men and≥ 460 ms in women (RR - 1.20, p = 0.03) and signs of LVH (RR- 1.16; p = 0, 004).
Conclusions. The results of this population-based study showed that the presence SRRZH in the bottom leads increases the risk of death from cardiac and arrhythmic causes. How SRRZH increases the risk of adverse outcomes is not established. According to the experimental data, the elevation of the point J is a marker of increased transmural in homogeneity of ventricular repolarization and may reflect a predisposition to ventricular tachyarrhythmias. "Future clinical and experimental studies should focus on clarifying the exact causes and mechanisms of development SRRZH and, ultimately, to develop strategies to prevent premature death from cardiac causes in patients with this disorder EKG" - the authors conclude the publication.
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