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Morning preference in onset of symptomatic third-degree atrioventricular heart block
Roberto Manfredini1, Massimo Gallerani, Benedetta Boari
1Internal Medicine and Hypertension Center, Department of Clinical and Experimental Medicine, University of Ferrara Medical School, Italy. mfr@unife.it
Insights
Third-degree atrio-ventricular (AV) heart block symptoms predominantly emerge in the morning hours. This circadian pattern, observed in male patients, mirrors trends in sudden cardiac death and cardiac arrest.
Area of Science:
- Cardiology
- Chronobiology
- Internal Medicine
Background:
- Third-degree atrio-ventricular (AV) heart block is a serious cardiac condition.
- Understanding the temporal patterns of symptomatic onset is crucial for patient management and research.
Purpose of the Study:
- To investigate the 24-hour patterning of symptom onset in third-degree AV block.
- To identify any specific time-of-day predilection for symptomatic presentation.
Main Methods:
- Retrospective analysis of 227 third-degree AV block cases diagnosed between 1990-2001.
- Onset times of symptomatic events were recorded and categorized into four 6-hour intervals.
- Statistical analysis, including chi-squared tests, was used to assess temporal patterns.
Main Results:
- Symptomatic third-degree AV block onset occurred significantly more often in the morning (06:00-11:59h) (p < 0.001).
- This morning preference was particularly evident in the male subgroup (p < 0.0001).
- No significant temporal pattern was detected in the female subgroup.
Conclusions:
- A distinct circadian rhythm exists for the onset of symptomatic third-degree AV block, favoring morning hours.
- This pattern is consistent with those observed in sudden cardiac death and cardiogenic cardiac arrest.
- The underlying etiology remains unknown, potentially involving biological rhythms or environmental triggers like ischemia.
Abstract:
The aim of this study was to examine 24h patterning in the symptoms indicative of third-degree atrio-ventricular (AV) heart block. We found a total of 227 cases (126 men and 101 women) of third-degree AV block that had been diagnosed by the Emergency Medical Department of the St. Anna Hospital in Ferrara, Italy between 1990 and 2001. Determination of the hour of onset of symptomatic third-degree AV block, however, was possible and listed in the records of only 161 or 70.9% of the cases (92 men and 69 women). The onset time of every event was categorized into one of four 6h spans of the 24h: night (00:00-05:59h), morning (06:00-11:59h), afternoon (12:00-17:59h), and evening (18:00-23:59h). The onset of the symptoms of third-degree AV block in the sample of 161 cases was significantly greater in the morning between 06:00 and 11:59h than any other 6h span of the day and night (chi2-test; p < 0.001). The same phenomenon was substantiated in the subgroup of the 92 males (chi2; p < 0.0001), although it could not be detected for the smaller subgroup of 69 women. The 24h pattern, with morning preference, in the onset of symptomatic third-degree AV block is similar to the one in sudden cardiac death and cardiogenic cardiac arrest. The etiology of the 24h pattern in symptomatic AV block is unknown; it may be an expression of intrinsic biological rhythmicity within the heart tissue or its control system, and/or the timing of environmental triggers resulting in coronary ischemia.