Relation Between the Ratio of Recovery to Peak Exercise Systolic Blood Pressure and the Presence and Extent of Myocardial Perfusion Abnormalities During Stress Reinjection TI-201 Scintigraphy

A delay in the decline of systolic blood pressure response after exercise is considered as an abnormal response. We studied the relation between the ratio of recovery systolic blood pressure to peak exercise systolic blood pressure (SBPR) and the presence and extent of myocardial perfusion abnormalities in 265 consecutive patients using stress-redistribution-reinjection Tl-201 scintigraphy. SBPR was measured as the systolic blood pressure 3 minutes after exercise divided by peak exercise blood pressure. According to Tl-20 1 results, cases were divided int o 4 groups: Group I consisted of normal scans (n=98), group II of patients with only reversible defects (n=90), group III of patients with only nonviable fixed defects (n=32), group IV of reversible and viable or nonviable fixed defects (mixed group, n=45). The mean SBPR was found as 0.84±0.13, 0.92±0.12, 0.91±0.12 and 0.93±0.17 in groups I-IV, respectively. There was a significant difference between normal subjects and patient groups, whereas the 3 patient groups did not show a significant difference among them. Using a cut-off value of ?0.90 identified from the receiver operating characteristic curve as the SBPR value which indicated an increased risk of perfusion abnormalities, SPBR had a sensitivity of 59 %, specificity of 63% and accuracy of 61% whereas exercise-induced ST depression had a sensitivity of 64%, specificity of 73% and accuracy of 68% (p=NS; p<0.05). The mean SBPR was 0.95±0.13 in patients with ?5 abnormal scan segments compared to 0.90 ± 0.14 in patients with 1-4 abnormal scan segments (p=0.007). However, a mild-moderate correlation was found between the number of segments and SBPR values with linear regression analysis (r=0.34). In conclusion, abnonnal SBPR may be related to either myocardial necrosis or ischemia and has a limited diagnostic accuracy for detecting the presence and extent of perfusion abnormalities.