Optimisation of therapeutic strategies for ST-segment elevation acute myocardial infarction: the impact of a territorial network on reperfusion therapy and mortality.

OBJECTIVE: To assess the clinical impact of a regional network for the treatment of ST-segment elevation myocardial infarction (STEMI). METHODS: All patients with STEMI (n = 1823) admitted to any of the hospitals of an area with one million inhabitants during the year 2002 (n = 858)-that is, before the network was implemented, and in 2004 (n = 965), the year of full implementation of the network, were enrolled in this study. The primary evaluation was in-hospital mortality. Secondary outcomes included the incidence of major adverse cardiac and cerebrovascular events (MACCE), defined as death, myocardial infarction, stroke and coronary revascularisation procedures over 1-year follow-up. RESULTS: Between 2002 and 2004, there was a major change in reperfusion strategy: primary angioplasty increased from 20.2% to 65.6% (p<0.001), fibrinolytic therapy decreased from 38.2% to 10.7% (p<0.001) and the rate of patients not undergoing reperfusion was reduced from 41.6% to 23.7% (p<0.001). In-hospital mortality decreased from 17.0% to 12.3% (p = 0.005), and this reduction was sustained at 1-year follow-up (23.9% in 2002 and 18.8% in 2004, p = 0.009). Similarly, the 1-year incidence of all MACCE was reduced from 39.5% in 2002 to 34.3% in 2004 (p = 0.01). CONCLUSIONS: Organisation of a territorial network for STEMI is associated with increased rates of reperfusion therapy and reduction of in-hospital and 1-year mortality.

Transient sympathovagal imbalance triggers "ischemic" sudden death in patients undergoing electrocardiographic Holter monitoring.

OBJECTIVES: The aim of this study was to investigate the relation between "ischemic" sudden death (arrhythmic death preceded by ST segment shift) and autonomic nervous system activity. Background. Mechanisms precipitating sudden death are poorly known despite the importance of detecting functional factors that may contribute to such a fatal event. METHODS: We analyzed the tapes of eight patients (seven men and one woman with a mean age of 66 +/- 8 years) who had ischemic sudden death during ambulatory electrocardiographic (Holter) monitoring. Four patients had unstable and four had stable angina; none was taking antiarrhythmic drugs. Twenty patients with angina and transient myocardial ischemia during Holter monitoring served as control subjects. Arrhythmias, ST segment changes and heart rate variability were analyzed by a computerized interactive Holter system. RESULTS: Five patients had ventricular tachyarrhythmias (ventricular fibrillation in three, ventricular tachycardia in two), and three had bradyarrhythmias (atrioventricular block in two, sinus arrest in one) as the terminal event; all eight patients showed ST segment shift (maximal change 0.46 +/- 0.16 mV; with ST elevation in two) that occurred 41 +/- 34 min (mean +/- SD) before sudden death. The standard deviation of normal RR intervals (SDNN) was 89 +/- 33 ms during the 10 +/- 6 h of Holter monitoring; 5 min before the onset of the fatal ST shift, SDNN measurements were significantly lower than during the initial 5-min period (48 +/- 10 vs. 29 +/- 9 ms; p=0.002). In control patients, the SDNN was 102 +/- 39 ms during Holter monitoring, whereas it measured 56 +/- 30 ms 5 min before the most significant episode of ST shift (p<0.01 vs. 29 +/- 9 ms [corrected] in the group with sudden death). CONCLUSIONS: Autonomic dysfunction, as detected by a marked decrease in heart rate variability, is present in the period (5 min) immediately preceding the onset of the ST shift precipitating ischemic sudden death. These data suggest that sympathovagal imbalance may trigger fatal arrhythmias during acute myocardial ischemia, thus resulting in sudden death.

[A transient decrease in heart rate variability in patients with sudden "ischemic" death during Holter monitoring]. / Riduzione transitoria della variabilità della frequenza cardiaca in pazienti con morte improvvisa "ischemica" durante Holter.

BACKGROUND: Mechanisms precipitating sudden death are poorly known, in spite of the importance to detect functional factors which may contribute to such fatal event. Aim of the study was to investigate the relationship between "ischemic" sudden death (ISD: arrhythmic death preceded by acute myocardial ischemia) and autonomic nervous system activity. METHODS: We analysed the tapes of 6 patients (pts) (5 males; 67 +/- 12 yrs) suffering ISD during Holter monitoring (HM). One pt had recent onset angina, 2 had unstable and 3 stable angina; none was taking antiarrhythmic drugs. Arrhythmias, ST segment and heart rate variability (HRV) were analysed by a computerized interactive HM system, in order to obtain data on transient ischemia and sympatho-vagal balance. RESULTS: Five pts showed ventricular tachyarrhythmias (2 VF, 3 VT), and 1 had a bradyarrhythmia (advanced A-V block) as the terminal event; all pts showed ST shift (max: 0.37 +/- 0.28 mV; 1 with ST elevation; 4 with anginal pain) 53 +/- 35 min before ISD. SD of normal R-R intervals (SDNN) was 112 +/- 26 msec in the 11 +/- 8 hrs of HM, whereas it was 97 +/- 48 msec in the initial hour and 59 +/- 21 msec in the initial 5 min segment. Measurements of SDNN showed a marked decrease 5 min before the onset of fatal ischemic ST shift: 32 +/- 14 msec (p = 0.003). Also, pNN50 (percent of adjacent R-R differing > 50 msec: marker of vagal activity) was significantly reduced before ISD, when compared to the initial 5 min segment (from 10 +/- 5 to 7 +/- 4%; p < 0.03). Such changes were not observed before uncomplicated (that is not associated with malignant arrhythmias) ST shift episodes during HM. CONCLUSIONS: Autonomic dysfunction, as detected by a marked decrease of HRV, is present in the period (5 min) immediately preceding the onset of ST shift precipitating ISD; simultaneous measurements of vagal signals showed similar changes. These data suggest that sympatho-vagal unbalance may trigger fatal arrhythmias during acute myocardial ischemia, hence resulting in ISD.