Is silent ischemia painless because it is mild?

[Prognosis of patients with angina pectoris or silent ischemia: exercise 99mTC-MIBI SPECT]

INTRODUCTION AND OBJECTIVES

Although different reports have compared the extent of the myocardial ischemia in patients with or without angina during exercise test, there have been few publications which have studied their prognosis. The aim of this study is to analyze the prognostic value of the presence of angina during 99mTc-MIBI SPECT in patients with proven coronary artery disease without previous myocardial infarction.

PATIENTS AND METHODS

We studied 82 patients prospectively with at least one coronary stenosis > 70% and with reversible perfusion defects in 99mTc-MIBI SPECT (long protocol). Twenty two of these patients had angina during exercise test. The extension of ischemia was quantified on SPECT and the severity of coronary stenoses on coronary angiography. The mean follow-up period was 3.2 years.

RESULTS

The angina patients showed a significantly lower coronary reserve (exercise duration: 6.3 min vs 8 min; p = 0.03), a lower maximal O2 consumption (5.8 METs vs 6.2 METs; p = 0.04), a higher rate of ST depression > 1 mm (64% vs 19%; p = 0.006) and a higher degree of ST depression (0.9 mm vs 0.4 mm; p = 0.01) than those patients without angina. There were no significant differences in the extent of ischemia in SPECT or in the angiographic severity of coronary disease between either groups. During the follow-up period the presence of severe complications (myocardial infarction or death) tended to be higher (27% vs 17%; NS) in patients with angina and the indication of surgical revascularization was also significantly higher (50% vs 17%; p = 0.002) in this group.

CONCLUSIONS

Presence of angina during 99mTc-MIBI SPECT portends a higher risk of medium and long term complications, mainly due to surgical revascularization.

The Psychophysiological Investigations of Myocardial Ischemia (PIMI) study: objective, methods, and variability of measures

OBJECTIVE

This study evaluated physiological, neuroendocrine, and psychological status and functioning of patients with coronary artery disease in order to clarify their role in the expression of symptoms during myocardial ischemia (MI), and to establish repeatability of responses to mental stress. Design and methods of the study are presented.

METHODS

One hundred ninety-six coronary artery disease patients were examined during physical and mental stress tests in four hospitals. Eligibility criteria included narrowing of at least 50% in the diameter of at least one major coronary artery or verified history of myocardial infarction, and evidence of ischemia on an exercise treadmill test. Psychological, biochemical, and autonomic function data were obtained before, during, and after exposure to mental and exercise stressors during 2 or 3 half-days of testing. Ventricular function was assessed by radionuclide ventriculography, and daily ischemia by ambulatory electrocardiography. Sixty patients returned for a short-term mental stress repeatability study. Twenty-nine individuals presumed to be free of coronary disease were also examined to establish reference values for cardiac responses to mental stress.

RESULTS

Study participants were 41 to 80 years of age; 83 (42%) had a history of MI, 6 (3%) of congestive heart failure, and 163 (83%) of chest pain; 170 (87%) were men; and 90 (46%) had ischemia accompanied by angina during exercise treadmill testing. Ischemia during ambulatory monitoring was found in 35 of 90 (39%) patients with and 48 of 106 (45%) patients without angina during exercise-provoked ischemia. Intraobserver variability of ejection fraction changes during bicycle exercise and two mental stress tests (Speech and Stroop) was good (kappa = 1.0, .90, and .76, respectively; percent agreement = 100, 97.5, and 93.8%, respectively). Variability of assessed wall motion abnormalities during bicycle exercise was better (kappa, agreement = 85%) than during Speech or Stroop kappa and .57, percent agreement = 70% and 82.5%, respectively).

CONCLUSIONS

Study design, quality control data, and baseline characteristics of patients enrolled for a clinical study of symptomatic and asymptomatic myocardial ischemia are described. Lower repeatability of reading wall motion abnormalities during mental stress than during exercise may be due to smaller effects on wall motion and lack of an indicator for peak mental stress.

Course of pain sensitivity in aging: pathogenetical aspects of silent cardiopathy

Aging is often considered a risk factor for silent ischemic cardiopathy. Using endermic electric stimuli, we assessed the course of pain threshold and pain tolerance in 23 male subjects affected by silent myocardial ischaemia, and in 20 male subjects with symptomatic cardiopathy; we also attempted to define the role played by age. Values of pain threshold were assessed using the same method in a group of 40 healthy subjects, five for each age decade, between 10 and 90 years. Our data show a significant difference in pain threshold and tolerance between subjects with silent and symptomatic cardiopathies (34.7 +/- 12.6 mA versus 25.2 +/- 12.5 mA: P < 0.001 for the threshold and 68.5 +/- 21.2 mA versus 46.0 +/- 22.3: P < 0.001 for tolerance). The fact that the significance of our results is superior to that of other studies may be due to the particular method of stimulation used and to the uniformity of the sample studied (sex, age, exclusion of subjects with anxiety-depressive symptoms). No difference was found in pain threshold as regards age. It seems probable that the difference found between subjects with silent and symptomatic cardiopathies is due to the different modulation of the perception of pain at a central level, independently of the age factor.

Ischemic burden in silent and painful myocardial ischemia: a quantitative exercise sestamibi tomographic study

OBJECTIVES

We sought to determine whether the amount of myocardial ischemic burden differs in patients with painful or silent myocardial hypoperfusion during exercise testing.

BACKGROUND

Whether a lack of symptoms during ischemia reflects an alteration in pain perception or less myocardium in jeopardy remains a controversial issue.

METHODS

We studied 300 consecutive patients with a well established history of ischemic heart disease and reversible hypoperfusion on exercise sestamibi tomography. Rest and stress sestamibi defects were quantitatively assessed and indexes of exercise left ventricular dilation derived.

RESULTS

Painful and silent reversible ischemia was observed in 97 (32%) and 203 (68%) patients, respectively. Patients with painful ischemia had lower values for work load, exercise time and peak rate-pressure product (p < 0.01) and more frequently showed significant ST segment depression during exercise than did patients with silent ischemia (69% vs. 40%, p < 0.001). On sestamibi tomography, patients with painful ischemia had more reversible hypoperfusion than did patients with silent ischemia (mean +/- SD 16 +/- 10% vs. 11 +/- 7%, p < 0.001), despite a comparable extent of stress hypoperfusion (22 +/- 12% vs. 22 +/- 13%); they also had a higher endocardial dilation index (1.32 +/- 0.32 vs. 1.10 +/- 0.26, p < 0.001). By multivariate logistic analysis, the most powerful correlate of painful ischemia was a history of effort angina; the extent of reversible perfusion defect was the sole independent scintigraphic correlate of painful ischemia.

CONCLUSIONS

To our knowledge, this is the largest study comparing the degree of hypoperfusion and the presence of symptoms during exercise stress testing in a consecutive cohort of patients with ischemic heart disease and reversible hypoperfusion. The results suggest that the ischemic burden is greater in painful than in silent ischemia.