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Prolonged electrical systole and QT greater than QS2 secondary to coronary artery disease
Insights
Left ventricular aneurysm significantly increases the risk of abnormal heart rhythms (long QT) in coronary artery disease patients. This suggests dyssynchronous electrical activity within the aneurysm contributes to these dangerous findings.
Area of Science:
- Cardiology
- Electrophysiology
- Cardiac Imaging
Background:
- Dyssynchronous depolarization-repolarization in the left ventricle (LV) can lead to QT prolongation.
- Left ventricular aneurysm is a known complication of coronary artery disease (CAD) and acute myocardial infarction (AMI).
Purpose of the Study:
- To investigate the incidence of abnormal QT intervals (QT > QS2 or long QT) in patients with CAD.
- To compare these findings in patients with and without LV aneurysm, and with or without a history of AMI.
- To assess the impact of digitalis therapy on QT intervals in patients with prior AMI.
Main Methods:
- Simultaneous measurement of QT and QS2 intervals in 41 patients with CAD and LV aneurysm, 46 with CAD and prior AMI (no aneurysm), and 52 with CAD only.
- Exclusion of patients on class I antiarrhythmic drugs.
- Analysis of QT intervals corrected for heart rate and QT > QS2 incidence.
Main Results:
- Incidence of QT > QS2 was significantly higher in LV aneurysm patients (71%) vs. prior AMI (22%) and CAD only (20%) (p<0.001).
- Incidence of long QT was significantly higher in LV aneurysm patients (54%) vs. prior AMI (7%) and CAD only (6%) (p<0.0001).
- Digitalis therapy in prior AMI patients increased QT > QS2 incidence (65% vs. 22%, p<0.001).
Conclusions:
- LV aneurysm is strongly associated with increased risk of abnormal QT intervals, likely due to myocardial dyssynchrony.
- Abnormalities in QT intervals were not significantly different between patients with prior AMI and those with CAD only.
- Digitalis may exacerbate QT prolongation in patients with prior AMI and LV dysfunction.
Abstract:
Dyssynchronous depolarization-repolarization in the left ventricular (LV) myocardium may produce QT greater than QS2 or long QT. In 41 patients with coronary artery disease (CAD) and LV aneurysm, 46 patients with CAD and a history of acute myocardial infarction (AMI) but no LV aneurysm, and 52 patients with CAD without previous AMI, QT and QS2 were measured simultaneously at a speed of 100 mm/s within 48 hours of cardiac catheterization. Patients receiving class I antiarrhythmic drugs were excluded. The incidence of QT greater than QS2 was significantly greater in patients with LV aneurysm (71%) than in those with previous AMI (22%) and those with CAD but no previous AMI (20%) (p less than 0.001). Likewise, the incidence of long QT corrected for heart rate was significantly greater in patients with LV aneurysm (54%) than in those with previous AMI (7%) and those with CAD and no previous AMI (6%) (p less than 0.0001). The incidence of QT greater than QS2 in another 19 patients with previous AMI who were receiving digitalis therapy was significantly greater (65%) than in those with previous AMI but not receiving digitalis therapy (22%) (p less than 0.001). The incidence of long QT corrected for heart rate and QT greater than QS2 was not statistically different between patients with previous AMI and those with CAD but no previous AMI. The QT greater than QS2 or long QT in patients with aneurysm is probably a result of dyssynchronous depolarization or repolarization within or in the border zone of the LV aneurysm.(ABSTRACT TRUNCATED AT 250 WORDS)