Aim of the study: Assessment of safety and diagnostic value of stress echocardiography protocol based on rapid pacing in patients with implanted permanent pacemakers operating in AAI/DDD and VVI modes.
Material and methods: 88 rapid pacing stress echo tests were performed in 60 patients (39M, 21F, aged 47-79, mean 64 +/- 9 years), utilizing permanent pacemakers. Left ventricular segmental contractility was assessed at rest and during 100/min and 85% of predicted maximal heart rate. Each pacing stage lasted for 3minutes. The test was performed with the use of AAI/DDD or VVI pacing mode and then repeated with WV mode in pts with DDD pacemaker. Coronary stenosis of at least 50% was considered significant. Mean duration of the test was 9.9 +/- 1.7 min, including 6.7 +/- 1.4 min of pacing.
Results: No severe adverse effects were observed. Among 88 tests performed, AAI/DDD modes were used in 41 and VVI mode in 47 were as significant increase of the heart rate comparing to baseline was achieved - 68 vs 129/min; p<0.0001, including patients treated with beta-blockers - 69 vs 128/min; p < 0.0001. No significant differences in systolic blood pressure were found between rest and stress (126 vs 126 mm Hg). In 58 patients (66%) the test was considered positive for ischemia, in 29 (33%), negative and in 1 (1%) nondiagnostic. Sensitivity, specificity, accuracy, positive and negative predictive values were respectively: 92%, 66%, 79%, 78% i 86%. For AAI/ DDD modes the above values calculated for the entire group were: 95%, 75%, 85%, 79%, 94%, while for VVI mode they were: 90%, 56%, 73%, 76%, 77% (NS). In the presence of left ventricular hypertrophy the accuracy was 79% for AAI/DDD and 71% for VVI mode, and in patients without hypertrophy 92% and 74% respectively.
Conclusions: A stress echo protocol using permanent pacemaker for rapid pacing is a brief and safe diagnostic technique. Accuracy of the test is similar regardless of the pacing mode used. The test can be utilized as a technique of choice for noninvasive diagnostics of coronary disease in patients with permanent pacemakers.