Sudden death in competitive athletes: does a circadian variation in occurrence exist?
05:59 PM; and evening, 06:00-11:59 PM). Group A was analyzed applying partial Fourier series, by means of a chronobiologic software that selects the harmonic(s) best explaining the variance of the data [14]. The percentage of rhythm (PR: percentage of the overall variability of data about the arithmetic mean) and the F test statistic are used to test the hypothesis of zero amplitude null hypothesis (absence of periodicity). The software also calculates the acrophase (peak) of each single harmonic and the peak and trough times of the overall best fitted curve. Significance was assumed for P b .05. Group B was analyzed by means of ?2 test goodness of fit [15].
Thirty-seven athletes with SD were included in group A (Table), and a total of 63 were included in group B (age, 18-37 years; mean, 26.6 +- 4.8 years). As for group A, chronobiologic analysis yielded a significant Circadian variation, characterized by a bimodal frequency peak. The main circadian peak (periodicity, 24 hours; PR, 52.5%; P b .001) was registered at 04:58 PM (95% confidence limits [CL], 15:32-18:24 PM), and a smaller accessory peak (periodicity, 12 hours; PR, 14.7%; P =
.029) was found at 08:29 AM/PM (96% CL, 06:34-09:18).
Overall, the circadian rhythm (peak at 07:00 PM, trough at 2:56 AM) was highly significant (PR, 67.3%; P b
.001) (Fig. 1). For group B, ?2 test showed a statistically significant difference (?2, 10.0; P = .024), with highest frequency of cases in the evening (n = 25, 39.7%) and lowest during night time (n = 7, 11.1%) (Fig. 2).
This preliminary study shows that also in athletes, SD exhibits a circadian pattern of onset, characterized by 2 frequency peaks. Muller et al [6] first revealed a prominent circadian morning incidence of SCD, with low nocturnal incidence [6], remarkably similar to that reported for nonfatal MI [4]. After adjustment for individual wake time, the onset of events was higher during the first 3 hours after awakening [16]. A same pattern was confirmed also for cardiac arrests [17-19], and further studies revealed the existence of a second peak in the afternoon-evening hours, maybe attri- butable to arrhythmias. Arrhythmic events exhibit circadian rhythm, also in apparently healthy subjects [20]. Arntz et al
[21] reported a marked circadian variation in the occurrence of SD with a primary morning peak and a secondary afternoon peak. The subgroup of patients with ventricular
Age |
Hour |
Sport discipline |
Date |
Country |
||
1 |
24 |
5:45 |
PM |
Soccer |
05/10/2000 |
Romania |
2 |
24 |
11:50 |
AM |
Boxing |
25/10/2000 |
USA |
3 |
33 |
2:37 |
PM |
Baseball |
02/06/2002 |
USA |
4 |
28 |
7:41 |
PM |
Soccer |
26/06/2003 |
Cameroon |
5 |
24 |
10:30 |
PM |
Soccer |
25/01/2004 |
Hungary |
6 |
30 |
10:14 |
PM |
Soccer |
27/10/2004 |
Brasil |
7 |
24 |
9:00 |
AM |
Soccer |
28/11/2004 |
Argentina |
8 |
28 |
3:30 |
PM |
Soccer |
12/04/2005 |
UK |
9 |
37 |
4:15 |
PM |
Cycling |
15/06/2005 |
Italy |
10 |
25 |
9:15 |
PM |
Boxing |
01/04/2007 |
Philippines |
11 |
22 |
8:30 |
PM |
Soccer |
25/08/2007 |
Spain |
12 |
28 |
8:46 |
AM |
Marathon |
03/11/2007 |
USA |
13 |
35 |
5:18 |
PM |
Soccer |
29/12/2007 |
UK |
14 |
27 |
0:00 |
AM |
Cycling |
11/03/2008 |
Portugal |
15 |
24 |
11:51 |
AM |
Soccer |
03/04/2008 |
Croatia |
16 |
33 |
9:00 |
PM |
Soccer |
07/07/2008 |
Romania |
17 |
19 |
5:03 |
PM |
Hockey |
13/10/2008 |
Russia |
18 |
21 |
5:30 |
PM |
Cycling |
05/02/2009 |
Belgium |
19 |
36 |
9:30 |
AM |
Marathon |
20/08/2009 |
USA |
20 |
26 |
10:30 |
AM |
Marathon |
20/08/2009 |
USA |
21 |
19 |
11:30 |
PM |
Soccer |
22/10/2009 |
Italy |
22 |
24 |
5:10 |
PM |
Basketball |
26/10/2009 |
Portugal |
23 |
25 |
12:13 |
PM |
Soccer |
15/11/2009 |
Italy |
24 |
31 |
3:30 |
AM |
Soccer |
16/11/2009 |
Mexico |
25 |
26 |
7:20 |
PM |
Hockey |
08/12/2009 |
Sweden |
26 |
26 |
8:21 |
AM |
Football |
17/01/2010 |
USA |
27 |
25 |
8:53 |
PM |
Soccer |
06/03/2010 |
Nigeria |
28 |
32 |
6:05 |
PM |
Soccer |
06/05/2010 |
Croatia |
29 |
26 |
7:00 |
PM |
Soccer |
08/05/2010 |
Brasil |
30 |
31 |
1:15 |
PM |
Soccer |
27/10/2010 |
Spain |
31 |
23 |
10:45 |
PM |
Football |
27/04/2011 |
USA |
32 |
34 |
1:06 |
PM |
Soccer |
04/08/2011 |
Japan |
33 |
30 |
4:10 |
PM |
Soccer |
13/11/2011 |
Belgium |
34 |
27 |
2:43 |
PM |
Soccer |
15/03/2012 |
India |
35 |
23 |
7:11 |
PM |
Soccer |
17/03/2012 |
UK |
36 |
20 |
3:50 |
PM |
Soccer |
18/03/2012 |
Italy |
37 |
37 |
10:00 |
PM |
Volleyball |
24/03/2012 |
Italy |
fibrillation as initially documented arrhythmia showed a
Table Cases of sudden death of competitive athletes with precise time of death
similar circadian variation, whereas patients with asystole or 5
pulseless bradyarrhythmias were more evenly distributed
during the daytime. Moreover, patients older than 65 years 4
had a monophasic distribution, whereas younger patients
had morning and afternoon peaks. Two peaks, approxi- 3
mately of the same size (8-11 AM, 4-7 PM) were confirmed
N
in a large cohort, out-of-hospital cardiac arrests [22]. The 2
evening peak was attributed primarily to the patients found
in ventricular fibrillation, whereas arrests with other 1
arrhythmias exhibited mainly a morning peak. Because
previous studies could be exposed to the selection bias 0
of excluding nocturnal unwitnessed deaths, Tofter et al
TIME (hours)
[23] studied patients with implanted cardioverter/defibrilla- tor and confirmed that a higher proportion of Ventricular tachyarrhythmias began in the late morning. Again, Behrens
Fig. 1 circadian distribution of cases of sudden death in competitive athletes during competition with precise (+- 30 minutes) time of death (n = 37). Superimposed is the best fitting curve.
18
16
14
12
10
N
8
6
4
2
0
NIGHT
MORNING
AFTERNOON EVENING
Anna Maria Malagoni MD, PhD
Fabio Manfredini, MD Vascular Diseases Center University of Ferrara
Italy E-mail addresses: [email protected]
Roberto Manfredini MD
Clinica Medica University of Ferrara
Italy E-mail address: [email protected]
Fig. 2 Circadian distribution of cases of sudden death in
competitive athletes during competition with both precise and
probable (within 6-hour period) time of death (n = 63).
et al [24] found that shock episodes terminating potentially life-threatening ventricular tachyarrythmias exhibited a primary morning peak and a secondary one, much smaller, between 4 and 8 PM. Regular exercise reduces the incidence of CHD and MI [25], but vigorous activity may enhance the risk of MI and SD among patients with occult or overt CHD [26,27]. Although with the limitations of small sample size and the possible conditioning effect of competition time schedule, it is interesting that the circadian pattern of SD onset in athletes resembles that of common people, with evening and morning peaks. It is possible that, in addition to vigorous exercise during competition, temporally related physiologic changes deter- mining electrical myocardial vulnerability may also play a triggering role. Further studies on larger databases will test these preliminary data and provide useful insights for prevention.
Alfredo De Giorgi MD
Clinica Medica University of Ferrara
Italy E-mail address: [email protected]
Federica Achilli La Nuova Ferrara Ferrara, Italy
E-mail address: [email protected]
Fabio Fabbian MD Marco Pala MD
Clinica Medica University of Ferrara
Italy E-mail addresses: [email protected]
[email protected] [email protected]
doi:10.1016/j.ajem.2012.04.027
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