Page 99 - Cardiac abnormalities after aneurysmal subarachnoid hemorrhage

methods used in these studies and difference in study population. Brouwers et al.21 found that all patients with aSAH, monitored with serial ECG’s, had ECG abnormalities. In the same study the authors found that poor outcome in patients with aSAH was associated with fast rhythm disturbances and/or electrocardiographic signs of cardiac ischemia. Arrhythmia’s occurred in 91% of patients monitored by 24 hour ECG monitoring after the onset of aSAH26. Common ECG changes in aSAH are sinus bradycardia (50%), ST-segment changes (50%), T-wave abnormalities (48%), prominent U-wave (44%), QT interval abnormalities (39%), signs of left ventricular hypertrophy (36%), and sinus tachycardia (20%).21, 23, 27 Recent studies show that ECG changes after aSAH are correlated with echocardiographic abnormalities and biochemical markers of myocardial damage. Studies on the predictive value of ECG changes on impaired left ventricular systolic dysfunction are conflicting. Mayer et al.23, in 1995, found that the presence of T waves or QT interval prolongation on any ECG was associated with 100% sensitivity and 81% specificity for echocardiographic left ventricular dysfunction. Davies et al.22 stated 15 years earlier that ECG changes have poor relation with echocardiographic abnormalities but are related to the severity of neurological injury. The latter is confirmed in a paper of Zaroff et al.28, who also found that ECG changes have no independent predictive value for all-cause mortality. This is in accordance with a recent retrospective study of 159 patients29 where ST depression was found to be more common in patients with poor outcome, but ECG changes were not independently related to outcome. The electrophysiological mechanism of the ECG changes seen in SAH remains unclear. Serum magnesium levels have been proposed as a possible factor. Van den Bergh et al.30 found that lower serum magnesium levels are related to a long QTc interval.
In our meta-analysis which is described in Chapter 2, we found that Q waves,
ST-segment depression, and T-wave abnormalities are associated with worsened
clinical outcome. However in the multivariable analysis of the SEASAH study
(Chapter 3) we found no independent clinical association of the ECG abnormalities
with outcome, which indicated that they may be used as an indicator of cardiac 7 dysfunction only. Patients with a normal ECG did not have cardiac dysfunction
(unpublished). In conclusion, ECG changes occur frequently following aSAH, are related to a more severe neurological injury, but cannot be used as an independent predictor of outcome.
General Discussion
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