Prognostic significance of modern tools for stratification of sudden cardiac death risk (case study of highly-skilled footballers)

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Candidate S.F. Zadvoryev1, 2
PhD, Associate Professor L.V. Lyuik3
Dr.Med., Professor O.B. Krysyu2, 4
Dr.Med., Professor A.G. Obrezan2, 4
1City diversified hospital № 2, St. Petersburg.
2St. Petersburg State University, St. Petersburg
3St. Petersburg Polytechnic University named after Peter the Great, St. Petersburg
4International Medical Center "Sogaz", St. Petersburg

Keywords: sports cardiology, sudden cardiac death, electrocardiogram, arrhythmia, cardiac conduction disorders.

Background. The prevalence of sudden cardiac death among athletes is 0.1-5 people per 100,000 athletes per year [5, 6, 11], which is 2.5 times higher than the general population one, and increases in proportion to the load intensity [11]. The registry-based studies have demonstrated that cardiovascular screenings help reduce the risk of sudden cardiac death by 89% [9]. The increase in the efficiency of the screening programs is accompanied by an increase in their cost [2, 4, 8], which results in the attempts to optimize them through simple methods such as electrocardiography (ECG) [3, 9, 12]. Today, the 12-lead ECG is the main screening tool in sports [1, 3]. To increase the specificity and efficiency of screening, several ECG analysis criteria have been established to diagnose the high-risk conditions in the athletic population. Most screening algorithms have the highest sensitivity at low specificity: the percentage of false-positive screening results is high, the percentage of false-negative results is low [4, 7]. As follows from the literature analysis, to date, there are no data on the long-term monitoring of sports results demonstrated by athletes at high risk of sudden cardiac death.

Objective of the study was to assess the prevalence of significant electrocardiogram abnormalities and the prognostic value of the existing risk of sudden death in highly-skilled football players.

Methods and structure of the study. We carried out a prospective cohort study to determine the incidence of the electrocardiogram patterns of high risk of sudden cardiac death based on the data obtained in the Russian highly-skilled athletes, members of the men's professional football teams (n=65, mean age - 23.3±6.4 years). Before the start of the season, we examined the athletes using the 12-lead ECG. Any deviation from the ECG standard was evaluated in accordance with the ACCF recommendations for the standardization and interpretation of ECG, 2009. The ESC criteria [7], "Stanford criteria" and "Refined criteria" [12] were used to separate the detected changes into physiological and pathological ones. During the survey, we determined the incidence of significant and insignificant heart rate and cardiac conductivity disorders according to the electrocardiogram data, as well as the dynamics of sports career during the 3-year follow-up period. The statistical data processing was made using the methods of descriptive statistics, non-parametric McNemar test, Mann-Whitney U-test, and Kolmogorov-Smirnov test of normal distribution. The analysis was carried out using the SPSS 17.0 software package (IBM Inc., USA).

Result and discussion. Changes in ECG were detected in 80% of cases and were presented mainly by non-pathological conditions: physiological changes in ECG were detected in 73% of athletes, or in 59% of all examined highly-skilled athletes (see Table 1).

Table 1. Frequency of various diseases, pathological signs and peculiarities of ECG in examined group of athletes

Sign

Abnormalities

Prevalence, %

I degree AV block

 

6.1

RHBBB

No

34.4

EVRS

No

35.4

ECG signs of LVH

Yes

9.2

Sinus brady-arrhythmia

No

18.8

Events of wandering of atrial pacemaker

Yes

3.2

LAE

Yes

1.6

SVA

Yes

9.6

VPB

Yes

3.2

Positive ECG results under the ESC criteria

 

21.5

Positive ECG results under the Stanford criteria

 

15.4

Positive ECG results under the Refined criteria

 

15.4


Note. AV block – atrioventricular block; RHBBB – right His bundle branch block; EVRS – early ventricular repolarization syndrome; LVH – left ventricular hypertrophy; ECG – electrocardiogram; LAE – left atrial enlargement; SVA – supraventricular arrythmia; VPB – ventricular premature beats; ESC – European Society of Cardiology.

According to the table, the more advanced and selective criteria of risk of sudden cardiac death provided a more specific diagnosis of ECG abnormalities (RR=0.72, p=0.046). It was observed that the presence of an abnormal ECG under the "Refined criteria" was associated with the increase of sports qualification: in the group of athletes with abnormal ECG, the improvement of sports skills was noted in 60% of athletes, and their skill development reduction - in 20% of athletes, while in the athletes with normal ECG - 20% and 48%, respectively (p=0.042 for the probability of improvement of the sports qualification). No cases of sudden cardiac death were identified during the study.

The data obtained indicate that screening with the use of different criteria of sudden cardiac death risk shows a different prevalence of high-risk conditions. The "Refined criteria" and "Stanford criteria" define a 28% narrower group of athletes at high risk as opposed to the ESC criteria. The prevalence of ECG abnormalities in our study was higher than that in the large population register, which is consistent with the increasing frequency of changes occurring with the growth of athletes' sports skills [3, 10]. A similar effect was previously observed in amateur athletes [10, 12]. The prospective observation data showed that the football players' high-risk status was associated with the long-term trainings to improve their athletic performance, which thus actualizes the dilemma of the relationship between high athletic potential and risk of fatal arrhythmias. There is a need to further conduct long-term prospective studies of the relationship between the risk of sudden cardiac death and tolerance to physical loads.

Conclusions. In highly-skilled football players, the electrocardiogram pattern of high risk of sudden cardiac death can be due to the growth of their sports skills. According to the European Heart Rhythm Association, the sudden cardiac death risk criteria are 28% less accurate than the refined and Stanford criteria due to the lower specificity, which should be taken into account when designing programs of screening the risk of sudden cardiac death in team sports.

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Corresponding author: piskun@imop.ru

Abstract

Objective of the study was to assess the prevalence of significant electrocardiogram abnormalities and the prognostic value of the existing risk of sudden death in highly-skilled football players.

Methods and structure of the study. We carried out a prospective cohort study to determine the incidence of the electrocardiogram patterns of high risk of sudden cardiac death based on the data obtained in the Russian highly-skilled athletes, members of the men's professional football teams (n=65, mean age - 23.3±6.4 years). During the survey, we determined the incidence of significant and insignificant heart rate and cardiac conductivity disorders according to the electrocardiogram data, as well as the dynamics of sports career during the 3-year follow-up period.

Study results and conclusions. The electrocardiogram changes (when analyzed on ACCF 2009 recommendations) were found in 80% of the subjects (52 athletes), while 74% of them (59% of the total number, or 38 athletes) were regarded as non-pathological according to all the risk criteria of sudden cardiac death. The total prevalence of abnormal electrocardiogram equaled 21% for ESC and 15% for Stanford criteria and their derivatives - "Refined criteria" (TP=0.72, p=0.046). Abnormal electrocardiogram changes were associated with the transition to a sports club of a higher skill level (from a duplicate team to the main or from a lower division team to a higher one) for 3 years of prospective study. The rate of skill improvement in the patients with abnormal electrocardiogram was 60%, in those with normal electrocardiogram - 20% (p=0.042). There were no reported sudden deaths during 3 years of prospective study.

In highly-skilled football players, the electrocardiogram pattern of high risk of sudden cardiac death can be due to the growth of their sports skills. According to the European Heart Rhythm Association, the sudden cardiac death risk criteria are 28% less accurate than the refined and Stanford criteria due to the lower specificity, which should be taken into account when designing programs of screening the risk of sudden cardiac death in team sports.