[Comparison of Holter electrocardiography and thallium 201 scintigraphy in the detection of myocardial ischemia].

OBJECTIVE OF THE STUDY

To compare ischemic changes (I) detected by Holter ECG (H ECG) to the myocardial perfusion defects found in 201 TI myocardial perfusion scintigraphy.

DESIGN

201 TI exercise test was made during the performance of a 24 hours H ECG. The validation of ST segment changes detected by H ECG during the exercise test was made on basis of reversible myocardial perfusion defects (RPD) detected on 201 TL and a relation between ST segment changes detected during the remaining 24 hours recording period and 201 TI (TI) RPD was established.

SETTING

The patients (pt) included in the study have come from Cardiology and Heart Surgery Clinics of a Central teaching hospital.

MATERIAL AND METHODS

20 pt with a high coronary artery disease prevalence have been submitted to a two lead (V5 and aVF) 24 hour H ECG during which they have performed a symptom limited bicycle exercise test followed by an injection of 201 TI with acquisition 5 minutes later. Ischemic episodes detected on H ECG were quantified and their relation with heart rate and symptoms was established. As far as 201 TI studies are concerned the fixed and reversible perfusion defects as well as their location were evaluated.

RESULTS

1. H ECG: 6 pt (30%) presented ST changes on H ECG during the exercise test and a total of 9 pt (45%) had ST changes during exercise and during the remaining period of H ECG. 2. TI: 19 pt presented perfusion defects images (fixed in 7, reversible in 14, both kinds of defects in 7). 3. H ECG validation: H ECG during exercise presented I in 6 out of 14 pt with RPD on TI (sensitivity = 43%). Six of these 8 pt, with negative H and positive TI, had a chronic myocardial infarction. All the 6 pt with negative TI had negative H ECG (specificity = 100%). 4. H ECG TI comparison: 7 (50%) of the 14 pt with RPD had ST changes on 24 hrs H ECG. Seven of 11 pt with negative H ECG had RPD in TI. Two pt with negative TI had positive H ECG. These 2 pt had during H ECG a higher heart rate (HR) than the HR recorded during the exercise test.

CONCLUSIONS

1. In pt with known CAD, TI has a high sensitivity and specificity to show perfusion defects. 2. Considering TI as gold standard, H ECG showed to be a useful method to detect I in the studied population (sens. = 43%; spec. = 100%). 3. H ECG revealed to be an important diagnostic tool in detecting additional I episodes beyond the ones recorded during TI exercise test.