Results:
Baseline characteristics and predictors of hypertensive response:Tables 1 and 2 summarize the baseline patient characteristics of all
patients and as a function of presence or absence of a hypertensive
response to dobutamine. The mean age was 59+ 12 years, 45% were
women, 71% had diabetes mellitus. Of the 249 patients 53 (21%) had a
hypertensive response.
As shown in table 2, hypertensive response was predicted principally by
higher baseline systolic blood pressure (p<0.0001). They also
had higher estimated left atrial pressure (p=0.02) with similar
prevalence of right atrial hypertension by size of inferior vena cava as
well as by physical examination. They were more likely to be on
angiotensin converting enzyme inhibitor or receptor blocker (p=0.01) and
had a trend towards larger number of anti-hypertensive medications
(p=0.06). Left atrial enlargement and LV hypertrophy were more frequent
in the hypertensive group (p=0.006 and p=0.01 respectively). On
multivariable analysis, only pre-stress systolic blood pressure was a
predictor of hypertensive response (p<0.0001). A graded
relationship between pre-stress systolic blood pressure and hypertensive
response was observed (table 3). A pre-stress systolic blood pressure of
160 or more was highly predictive of hypertensive response during
dobutamine stress (Table 3). Pre-stress diastolic blood pressure was not
predictive of stress induced hypertensive response.
Stress test positivity and their angiographic correlates:Hypertensive response resulted in far more peak stress wall motion
abnormalities than normotensive group patients (OR 2.75, 95% CI
1.44-5.24, P = 0.002). As shown in figure 1, 25 (47%) of the 53
patients with hypertensive response had stress induced wall motion
abnormalities; of these 22 patients underwent coronary angiography and
12 (54%) were abnormal. Additionally, 12 of the 28 patients from
hypertensive group without systolic wall motion abnormalities were also
referred for coronary angiography and 7 (58%) were positive for
significant coronary artery disease. Even though some patients had
normal dobutamine stress echo, they underwent coronary angiography
because of request by the transplant committee.
In the normotensive response group (n= 196), only 48 (24%) patients had
stress induced wall motion abnormalities; of these 42 underwent coronary
angiography and 18 (43%) had significant CAD. In addition, 75 patients
from normotensive group without stress induced wall motion abnormalities
also received coronary angiography on the request of the transplant
committee and 22 (29%) had significant CAD. Thus, the sensitivity of
dobutamine stress test in normotensive group was 46% and specificity
was 66% (table 4).
Prognostic implications: Hypertensive response during stress test
was not predictive of mortality over the duration of follow-up (Figure
2). Stress induced wall motion abnormalities were predictive of higher
mortality in the normotensive group (p=0.03), but not in the
hypertensive group (Figure 3).