BackgroundAdenosine‐assisted transthoracic Doppler‐derived coronary flow reserve (TDE‐CFR) reflects coronary vascular function. The prognostic and incremental value of left anterior descending coronary artery TDE‐CFR above myocardial perfusion scintigraphy in patients with suspected myocardial ischemia has not yet been studied.Methods and ResultsThree hundred seventy‐one patients (mean age, 62.3±8.7 years; 46.8% males) referred to myocardial perfusion scintigraphy attributed to suspected myocardial ischemia were included in the study. The TDE‐CFR result was blinded to the referring physician. Patients were followed up regarding major cardiovascular events, defined as cardiovascular death, myocardial infarction, or acute revascularization during a median follow‐up time of 4.5 years. A TDE‐CFR value of ≤2.0 was considered reduced. Major cardiovascular events occurred during follow‐up in 60 patients (16.2%). A reduced TDE‐CFR was detected in 76 patients (20.5%). Patients with reduced TDE‐CFR had an event rate of 36.8% compared to 10.8% in patients with normal TDE‐CFR (unadjusted hazard ratio, 4.63; 95% CI, 2.78–7.69; P<0.001). In a multivariate model, TDE‐CFR remained a significant independent predictor of major cardiovascular events. The major cardiovascular events rate was 7.5% in patients without myocardial perfusion scintigraphy‐detected myocardial ischemia and normal TDE‐CFR (n=200), 24.2% in patients without ischemia but with reduced TDE‐CFR (n=33), and 46.5% in patients with both myocardial perfusion scintigraphy–detected myocardial ischemia and a reduced TDE‐CFR (n=43; P<0.001).ConclusionsCoronary microvascular dysfunction, as determined by TDE‐CFR, is a strong independent predictor of cardiovascular events and adds incremental prognostic value compared with myocardial perfusion scintigraphy. The current study supports routine assessment of CFR in patients with suspected ischemic heart disease.
Autonomic function and hemodynamics were studied in nine spinal cord injured (SCI) subjects, at rest and during peripheral afferent stimulation, bladder percussion. Nine able-bodied subjects were studied for comparison during unstimulated conditions. Spontaneous baroreceptor reflex sensitivity was calculated from recordings of ECG and intraarterial blood pressure. An index of sympathetic activity was provided by measuring total body noradrenaline (NA) spillover by isotope dilution technique. Renal vascular resistance was calculated from PAH-clearance.SCI subjects had lower total body NA spillover (1011 +/- 193 vs 2261 +/- 328 pmol/min, P < 0.01), but similar baroreceptor reflex sensitivity and hemodynamics compared to able-bodied subjects at rest. In SCI group, during bladder percussion, mean arterial pressure increased (79 +/- 5 vs 113 +/- 8 mm Hg, P < 0.01), whereas heart rate was reduced during the first minute of the manoeuvre (62 +/- 2 vs 56 +/- 2 bpm, P < 0.05). Baroreceptor reflex sensitivity remained unchanged. Total body NA spillover and renal vascular resistance increased by 332 % (from 1004 +/- 218 pmol/min, P < 0.05) and 55 % (from 0.078 +/- 0.011 mmHg/ml/min, P < 0.05), respectively.SCI subjects demonstrated lower total body sympathetic outflow but normal baroreceptor reflex sensitivity at rest, suggesting a balanced autonomic output to the heart. Bladder percussion caused a substantial increase in renal vascular resistance and blood pressure, which was partly due to marked generalised sympathetic activation. This activation was counterbalanced by an increased vagal activity as evidenced by reduction of the heart rate.
We conclude that BEI, which is markedly reduced in hypertensive patients with CRF, may convey information on arterial baroreflex function that is complementary to BRS.
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