ST-T alternans was observed in 35% of patients with Prinzmetal's variant angina who experienced ventricular arrhythmias during ischaemia, compared to 0% in those without arrhythmias.
Observational (n=86)
Is ST-T alternans a reliable marker for ventricular arrhythmias during myocardial ischaemia in patients with Prinzmetal's variant angina, and which drugs prevent these arrhythmias?
ST-T alternans is a reliable marker for ventricular arrhythmias during myocardial ischaemia in Prinzmetal's variant angina, and calcium antagonists like diltiazem may be effective in preventing them.
Absolute Event Rate: 35% vs 0%
Malignant ventricular arrhythmias appearing during acute myocardial ischaemia, are the most frequent mechanism of sudden death. ST-T alternans is the result of an intraischaemic conduction delay and is frequently associated with those potentially lethal arrhythmias. In fact, such a phenomenon was seen in 35% of 46/86 patients with Prinzmetal's variant angina who showed ventricular arrhythmias during ischaemia, while it was never observed in the remaining 40 patients without arrhythmias during ischaemia. Therefore ST-segment alternans should be considered a reliable marker of the possible occurrence of ventricular arrhythmias during myocardial ischaemia. ST-T-segment alternans is associated with R alternans, as clearly demonstrated by thoracic maps, and this phenomenon is due to a 2:1 intraischaemic block. The patients with Prinzmetal's variant angina who present ventricular arrhythmias during ischaemia, show a more prominent increase of the positive area of the QRS (411.75 +/- 102.5 vs 294.05 +/- 80.3 mu volts ms), that is, a more relevant intraischaemic conduction delay. The effects of different pretreatments (lidocaine, propranolol and diltiazem) on arrhythmias related to vasospastic myocardial ischaemia induced by ergonovine maleate, were evaluated in four patients with Prinzmetal's variant angina. As in experimental observations, neither a 'pure' antiarrhythmic agent like lidocaine, nor a betablocking agent like propranolol, prevented acute ischaemic ventricular arrhythmias. Only the calcium antagonist, diltiazem, seemed to prevent such arrhythmias. However, these findings necessitate further confirmation.
M.F. Oliver (Wed,) conducted a observational in Prinzmetal's variant angina (n=86). Ventricular arrhythmias during ischaemia vs. No ventricular arrhythmias during ischaemia was evaluated on ST-T alternans. ST-T alternans was observed in 35% of patients with Prinzmetal's variant angina who experienced ventricular arrhythmias during ischaemia, compared to 0% in those without arrhythmias.