Key result
Adrenergic stimulation via insulin infusion caused a significantly greater increase in the LF/HF ratio in vasospastic angina patients with ST depression compared to those without (34% vs 4%, p<0.05).
Why the study?
Does insulin-induced sympathetic stimulation trigger coronary vasospasm and alter autonomic nervous system activity in patients with vasospastic angina?
Observational (n=30)
Does insulin-induced sympathetic stimulation trigger coronary vasospasm and alter autonomic nervous system activity in patients with vasospastic angina?
Absolute Event Rate: 34% vs 4%
p-value: p=< 0.05
Increased vagal tone and hyperreactivity to adrenergic stimulation trigger coronary vasospasm in patients with vasospastic angina.
May indicate heightened sympathetic reactivity in vasospastic angina with ST depression; hypothesis-generating and should not yet change practice.
The relationship between autonomic nervous system activity (ANA) and coronary vasoreactivity during transient myocardial ischemia was determined in patients with vasospastic angina (VA). ANA was measured by power spectral analysis of heart rate variability and humoral factors following intravenous infusion of insulin in 24 patients with VA and 6 control patients. Nine (38%) of the VA patients had significant ST segment depression (STD), and 4 of these patients had symptomatic STD. The frequency of anginal episodes in the 9 patients with VA and STD was significantly greater than that in the 15 VA patients without STD (3.4 +/- 3.1 vs 0.5 +/- 0.8 episodes/week, p < 0.05). The increase in the LF/HF ratio 30 min after insulin injection in patients with STD was significantly greater than that in patients without STD (34 +/- 31% vs 4 +/- 34%, p < 0.05). All of the patients with VA and STD had significant coronary vasospasm in response to the infusion of < or = 20 micrograms of acetylcholine, higher levels of nocturnal parasympathetic activity, and greater norepinephrine production in response to insulin stimulation than the VA patients without STD. These findings suggest that increased vagal tone and hyperreactivity to adrenergic stimulation may trigger vasospasm in patients with VA.
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Saitoh et al. (1998) conducted an observational in Vasospastic angina (n=30). Intravenous infusion of insulin vs. Patients without ST segment depression was evaluated on Increase in the LF/HF ratio 30 min after insulin injection (p=< 0.05). Adrenergic stimulation via insulin infusion caused a significantly greater increase in the LF/HF ratio in vasospastic angina patients with ST depression compared to those without (34% vs 4%, p<0.05).
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