GW24-e2110 Analysis of Holter changes at acute and convalescence stage of myocardial infarction

Objectives Acute myocardial infarction can cause various arrhythmias. It is postulated that activation of autonomic nervous system induced arrhythmias. The developments of dynamic electrocardiogram provide some methods to evaluate the alternations of autonomic nervous system. In the present work, we sought to observe the changes of dynamic electrocardiogram at acute and convalescence stage of myocardial infarction. Methods Between May 2012 and December 2012, 64 patients including STEMI and NSTEMI were involved, 49 males and 15 females, mean age 64.3 + 10.6. Each participant underwent dynamic electrocardiogram recording during acute (5 to 7 days) andconvalescence stage (5–6 months) of myocardial infarction. For heart rate variability (HRV) analysis, SDNN, SDANN, PVV50 and HRV triangular index (HRVTI) were measured. For heart rate turbulence (HRT) analysis, Tubulence onset (TO), tubulence slope (TS) and tubulence dynamics (TD) were measured. Microvolt TWA (MTWA) was determined during the period of maximal heart rate and around 8:00 am in 30 couples of Twave of sinus rhythm. Results The recording time was comparable between acute and convalescence stage in each patient. Acute stage has significantly increased heart rate compared with convalescence stage, in terms of mean heart rate (76.15 ± 8.85 bpm vs. 69.23 ± 6.26 bpm, P < 0.01), maximal heart rate (139.1 ± 17.93 bpm vs. 124.8 ± 13.09 bpm, P < 0.01) and minimal heart rate (48.67 ± 10.50 bpm vs. 43.04 ± 5.75 bpm, P < 0.01). Acute stage also has higher frequency of atrial (80.57 ± 6.36 beats vs. 24.07 ± 11.61 beats, P < 0.01)and ventricular premature beats (823.47 ± 64.42 beats vs. 79.45 ± 41.82 beats, P < 0.01) compared with convalescence stage. The parameters concerning HRV analysis were all decreased in acute stage compared to convalescence stage, in terms of SDNN (170.32 ms ± 57.13 ms vs. 199.86 ms ± 44.60 ms, P < 0.05), SDANN (166.79 ms ± 58.63 ms vs. 187.43 ms ± 39.66 ms, P < 0.05), PNN50 (6.19% ± 1.51% vs. 11.92% ± 3.53%, P < 0.05) and HRVTI (29.63 ± 10.83 vs. 39.65 ± 9.42, P < 0.01). The HRT analysis revealed that acute stage has significantly decreased TO (170.32% ± 57.13% vs. 199.86% ± 344.60%, P < 0.05), TS (166.79 ms/R-R ± 58.63 ms/R-R vs. 187.43 ms/R-R ± 39.66ms/R-R, ms/R-R,P < 0.05) and TD (6.19 ± 15.1 vs. 11.92 ± 3.53, P < 0.05). The TWA analysis showed that acute stage has lower degree of MTWA around 8:00 am (105.31 ± 6.23 vs. 205.63 ± 7.40, P < 0.05) and during maximal heart rate (135.63 ± 6.14 vs. 167.72 ± 8.30, P < 0.05) recordings. Conclusions The present work provides direct evidence indicating an increased trend for atrial and ventricular arrhythmias during acute stage of myocardial infarction. These abnormalities of cardiac electrophysiological properties may be related to an altered balance between sympathetic and parasympathetic nerve functions, especially an diminished parasympathetic response during acute stage.