Harold G. Olson

Submaximal exercise testing after stabilization of unstable angina pectoris

To determine the prognostic value of exercise testing in patients with unstable angina pectoris, 125 hospitalized patients were prospectively evaluated soon after stabilization of their pain. Exercise testing was performed after exclusion of acute myocardial infarction and a pain-free period of at least 3 days (mean +/- SD 3.9 +/- 1.4). No complications were noted during or immediately after exercise testing. A positive test (angina or greater than or equal to 1 mm ST segment depression, or both) was noted in 60 patients (48%). During a 1 year follow-up period, 52 (87%) of these 60 patients had an unfavorable outcome (American Heart Association class III or IV angina, recurrent unstable angina, coronary artery bypass surgery, acute myocardial infarction or cardiac death) compared with 19 (29%) of the 65 patients with a negative test (p less than 0.001). The sensitivity and specificity of exercise testing in predicting outcome were 73 and 85%, respectively. The predictive value of a positive test was 87% and that of a negative test was 71%. Angina by itself during the exercise test was a reliable predictor of severe angina (class III or IV angina) at follow-up (sensitivity 92%, specificity 89%, positive predictive value 83% and negative predictive value 95%; p less than 0.001). The findings were not significantly affected by beta-adrenergic blocking agents or digitalis in the study sample. Thus, in patients with unstable angina which has been stabilized, the results of early submaximal exercise testing may be useful in predicting outcome in the first year after hospital discharge. Patients with a positive test result should be considered for further diagnostic studies.

Early exercise testing after stabilization of unstable angina: Correlation with coronary angiographic findings and subsequent cardiac events

To evaluate the safety and diagnostic use of exercise testing in patients with unstable angina, 78 patients underwent submaximal exercise testing and diagnostic cardiac catheterization early after stabilization of their pain. Thirty-six patients (46%) had a positive exercise test manifested as angina or ST segment depression of greater than or equal to 0.1 mV during or immediately after exercise. Thirty-three of 36 patients (92%) with a positive exercise test had multivessel coronary disease compared to 18 of 42 patients (43%) with a negative exercise study (p less than 0.001). Twenty-two of 36 patients (61%) with a positive exercise test had three-vessel disease compared to 12 of 42 patients (29%) with a negative test (p = 0.004). The sensitivity of exercise testing in detecting multivessel disease was 65%, specificity 89%, predictive value of a positive test 92%, predictive value of a negative test 57%, and overall accuracy 73%. When the 42 patients taking beta blockers were examined, these values were essentially unchanged. Ventricular arrhythmias during exercise testing were associated with a lower ejection fraction, 61.1 +/- 12.5%, compared to 67.9 +/- 11.1% in patients without ventricular arrhythmias (p less than 0.05). Submaximal exercise testing after stabilization of patients with unstable angina is safe and useful in evaluating patients for the presence of multivessel coronary artery disease.

A randomized controlled trial of intravenous streptokinase in evolving acute myocardial infarction

To determine the efficacy of intravenous streptokinase in acute myocardial infarction, 52 patients were randomized to intravenous streptokinase or control groups. Time from onset of infarction to randomization was similar in the streptokinase group and control group, 4.9 +/- 2.1 hours vs 5.4 +/- 2.4 hours, respectively. The 28 streptokinase patients received an intravenous infusion of 700,000 units of streptokinase followed by full-dose anticoagulation. The 24 control patients received normal saline solution followed by full-dose anticoagulation. Of 28 streptokinase patients, 12 (43%) had noninvasive evidence of reperfusion by early peaking of serum creatine kinase (peak creatine kinase less than 16 hours after onset of infarction) vs 3 of 24 control patients (13%), p less than 0.02. Two streptokinase patients (7%) had reperfusion arrhythmias during streptokinase infusion. One streptokinase patient (4%) and two control patients (8%) died during hospitalization. At angiography (16 +/- 5 days after infarction) 22 of 26 streptokinase patients (85%) had a patent infarct-related coronary artery compared to 8 of 20 control patients (40%), p less than 0.01. Comparison of radionuclide left ventricular ejection fraction assessed acutely (28 +/- 10 hours after infarction) with left ventricular ejection fraction at hospital discharge (15 +/- 3 days after infarction) showed no significant improvement in either the streptokinase or control group, 0% and +1%, respectively. At follow-up 13 +/- 7 months after infarction, total mortality rate was similar in the streptokinase group and control group, 17.8% (5 of 28 streptokinase patients) and 20.8% (5 of 24 control patients), respectively.(ABSTRACT TRUNCATED AT 250 WORDS)

Effect of coffee on exercise-induced angina pectoris due to coronary artery disease in habitual coffee drinkers

The acute effects of coffee on exercise-induced angina were studied in 17 men with coronary artery disease using a double-blind treadmill protocol. Ingestion of either 1 or 2 cups of caffeinated coffee increased the exercise duration until onset of angina (8 and 12%, respectively, p less than 0.05), whereas decaffeinated coffee had no effect. The extent of ST-segment depression and the heart rate-blood pressure product at angina were similar after drinking caffeinated and decaffeinated coffee. Exercise duration until 0.1 mV of ST-segment depression, as well as the heart rate, blood pressure and double product at angina and at 0.1 mV of ST-segment depression were similar after drinking caffeinated or decaffeinated coffee. The mean serum caffeine levels (+/- standard deviation) after ingestion of 1 and 2 cups of caffeinated coffee were 1.97 +/- 1.0 and 3.89 +/- 1.6 micrograms/ml, respectively. The acute ingestion of 1 to 2 cups of caffeinated coffee had no deleterious effect on exercise-induced angina pectoris in patients with coronary artery disease.

Prognostic implications of complicated ventricular arrhythmias early after hospital discharge in acute myocardial infarction: A serial ambulatory electrocardiography study

To assess the prevalence and prognostic implications of complicated ventricular ectopic depolarizations (VEDs) after hospital discharge in patients with acute myocardial infarction (AMI), we obtained serial 24-hour Holter recordings in 85 patients during the first 6 weeks after AMI. Recordings were obtained during two coronary care unit time intervals, two hospital ward time intervals, and during four weekly time intervals after discharge. Complicated VEDs were defined as unifocal VEDs greater than or equal to 10/1000 beats for 24 hours, multiform VEDs, pairs, or ventricular tachycardia. At 1 year follow-up, there were nine cardiac deaths (six sudden deaths and three deaths from recurrent AMI). The mean left ventricular ejection fraction at discharge in the cardiac death patients was 29 +/- 12% (sudden death patients 24 +/- 11% and AMI death patients 40 +/- 6%) compared to 49 +/- 13% in the survivors (p less than 0.001). Patients with complicated VEDs at discharge (2 weeks after AMI) or during the first 4 weeks after discharge (3 to 6 weeks after AMI) were significantly more likely to have sudden death at follow-up compared to patients without complicated VEDs. Of the six sudden death patients, four (66%) had complicated VEDs at discharge compared to 18 of 68 survivors (26%) (p less than 0.05). One of three patients who died of recurrent AMI had complicated VEDs. No Holter data were obtained at hospital discharge in eight of the survivors.(ABSTRACT TRUNCATED AT 250 WORDS)

Pyrophosphate myocardial imaging

Technetium-99m pyrophosphate myocardial scintigraphy is a sensitive indicator of acute myocardial infarction (AMI). Over 90% of acute myocardial infarctions will result in an abnormal scintigram. The sensitivity is highest for transmural myocardial infarction, reaching levels of 95% or better. The positivity rate for subendocardial infarction ranges from 40% to 88% depending on the criteria used for interpreting the study. The threshold for positivity may be established using the intensity level present within the myocardium, on the presence or absence of localization within a specific wall of the myocardium, or a combination of both. The more stringent the criteria and the higher the threshold for positivity, the greater will be the specificity for acute infarction. The high specificity will, however, be at the expense of a lower sensitivity. Several other pathologic conditions can yield a positive myocardial scintiphotogram. Most commonly these are other forms of coronary artery disease in which frank myocardial infarction is not occurring. The cause of positive scintiphotograms in the absence of acute myocardial infarction is not known. It may be that with ischemia there are small focal areas of necrosis or that pyrophosphate concentration occurs purely on the basis of the ischemia. In the absence of infarction, the pattern of positivity is usually diffuse rather than localized in a specific wall. There are exceptions to this, most notably with ventricular aneurysms; however, the presence of a localized abnormality generally increases the specificity of a positive scintiphotogram for AMI. A positive scintigram in the absence of acute infarction has prognostic value in coronary artery disease for some conditions. A persistently positive study following a remote infarction is associated with an increased morbidity and mortality. Likewise, a positive scintiphotogram before coronary artery bypass surgery portends a higher surgical risk. Other indications for the examination include the diagnosis of perioperative infarction and right ventricular infarction. Less common entities such as metastasis to the myocardium, myocardial trauma, radiation therapy, or any other entity leading to significant myocardial injury or cellular death may result in an abnormal scintiphotogram.

Technetium-99m stannous pyrophosphate myocardial scintigrams in pericardial disease.

Technetium-99m stannous pyrophosphate (99mTc-PYP) myocardial scintigrams were obtained in 35 acute pericarditis and in three chronic constrictive pericarditis patients. Thirteen of 35 acute pericarditis patients (37%) and one of three chronic constrictive pericarditis patients (33%) had abnormal scintigrams (a diffuse pattern in eight patients and a regional pattern in six patients). Of the 17 acute pericarditis patients with classic ST-segment changes of acute pericarditis, 10 (56%) had abnormal scintigrams compared to three of 17 patients (18%) without these ECG changes (P less than 0.02). These data indicate that pericardial disease may cause an abnormal scintigram. Therefore, one must rule out pericardial disease before concluding that a positive scintigram is due to acute myocardial infarction.

Hemodynamic effects of verapamil in left ventricular valvular volume overload

The hemodynamic consequences of aortic and mitral insufficiency may be influenced by the high systemic vascular resistance often seen in these patients. Since the calcium antagonists have been shown to reduce systemic vascular resistance, we evaluated the effects of intravenous verapamil in 23 patients. In 11 patients with aortic insufficiency, verapamil resulted in a 20% increase in cardiac index (p less than 0.001), 18% increase in forward stroke volume index (p less than 0.001), and a 24% decrease in regurgitant fraction (p less than 0.005). In the 12 patients with mitral insufficiency, verapamil resulted in a 19% increase in both cardiac index (p = 0.004), and forward stroke volume index (p less than 0.001), while there was a 19% decrease in regurgitant fraction (p less than 0.02). Left ventricular end-systolic stress decreased significantly in both groups as did end-diastolic stress in the mitral insufficiency group. There was no significant change in several measures of contractile performance, though the end-systolic stress-to-volume index ratio fell significantly (p less than 0.04) in the mitral insufficiency group. Our findings suggest that the vasodilatory effects of intravenous verapamil predominate over the negative inotropic effects in patients with aortic and mitral insufficiency. Verapamil may be of use in patients intolerant to other vasodilators, patients with concomitant ischemic heart disease, or those with supraventricular arrhythmias.

Persistence of an Abnormal Pattern on 99mTc Pyrophosphate Myocardial Scintigraphy Following Acute Myocardial Infarction

Seventy patients, 69 males and one female, were studied by 99mTc pyrophosphate myocardial scintig-raphy more than six weeks after a documented myocardial infarction. History, physical examination, ECG, and serum enzyme measurements were obtained at the time of scintigraphy. All 70 patients were outpatients with no evidence of recurrent infarction since their myocardial infarction. Sixty-four of the 70 patients had angina pectoris or congestive heart failure. The scintigrams were interpreted by two observers. Images were scored on a scale of 1 + to 3 + for intensity of myocardial activity and were either diffuse or regional in distribution. Activity of 2 + or greater was considered positive. Of the 70 patients, 36 (51%) had myocardial scintigrams which were interpreted as positive for acute myocardial infarction and 34 (49%) as negative for acute myocardial infarction. Correlation of the clinical status with the scintigram revealed the following: all six asymptomatic patients had negative scintigrams; of the 32 patients with Class II angina, 15 were positive and 17 were negative; 10 of 14 patients with Class III angina were positive; 8 of 11 with angina and congestive heart failure (CHF) were positive; and 3 of 7 with CHF alone had positive scintigrams. In 54 of the patients who had previous scintigraphy at the time of acute infarction, the followup scintigram showed definite improvement in 48 patients and was the same or worse in 6 patients. Of these 6 patients, 2 showed scintigraphic evidence of reinfarction with a focal abnormality involving a different wall than on the original study. Furthermore, these were the only 2 among the 70 patients where the myocardial activity was graded at 3 +. Therefore, patients who have had previous myocardial infarctions with no clinical evidence of recurrent infarction may have persistent abnormalities on repeat myocardial scintigraphy. Meaningful interpretation is possible, however, by correlation with the clinical status and comparison with previous scintigraphy.