Signaling prodromes of sudden cardiac death
The new criteria in detection of ARVC/D produced more subtle noninvasive parameters that raised sensitivity in diagnosis. Since heart rate dynamics have prognostic significance for the progression of a disease and for mortality, the main objective was to explore its value in disclosing risk for serious arrhythmias.
Out of 100 ARVC/D patients, 35 with normal ECG Holter recordings (PVC<ioo) and no medical treatment (either antiarrhythmic or proar-rhythmic drugs) were analyzed according to severity of ARVC/D (Group 1/mild, n=23 and Group 2/overt, n=12) and regarding positive late potentials (noise interval between 0.1-0.3 μV). Severity of ARVC/D is defined: group 1 with no clinical recognizable signs and group 2 with clinical readily recognizable signs. Group 3 (control) consisted of 35 randomly assigned healthy subjects. The differences between the 3 groups were assessed by ANOVA followed by Bonferronbs post hoc multiple-range tests.
NLD methods, as opposed to linear time and frequency, show very significant differences between investigated groups vs. control. NLD methods by mean of the standard deviations of all NN intervals of sinus beats for all 5-minute segments (SDNN index) showed prevalence of parasympathetic activity as opposed to control. This was even more obvious through interpolation of data as % of deviation of Mean NN interval in function % frequency (p<0.005).
NLD methods describe complex rhythm fluctuations in ARVC/D patients that put insight at proarrhythmic potential of affected subjects. Furthermore, in combination with late potentials they improve recognizing hidden risks for serious arrhythmias.