Effect of thrombolysis on acute mitral regurgitation during evolving myocardial infarction. Experience from the Thrombolysis in Myocardial Infarction (TIMI) Trial

OBJECTIVES

This study was undertaken to determine whether early successful thrombolysis can reverse infarct-associated mitral valve dysfunction.

BACKGROUND

Mitral regurgitation is a common complication of acute myocardial infarction and has been shown to adversely affect both short- and long-term prognosis. Although anecdotal reports have suggested that reperfusion of the infarct-related artery may restore normal function to the mitral valve, this theory has not been subjected to formal investigation.

METHODS

Patients with total or partial obstruction of the infarct-related artery received intravenous thrombolytic therapy with either streptokinase or recombinant tissue-type plasminogen activator within 7 h of symptom onset (mean 4.8 h) as part of the Thrombolysis in Myocardial Infarction (TIMI) Phase I trial. Repeat coronary angiography assessed arterial patency at 90 min and 10 days after attempted reperfusion. The presence and severity of mitral regurgitation were determined by contrast ventriculography both before thrombolysis and before hospital discharge.

RESULTS

Overall, 21 (16%) of the 132 study patients exhibited mitral regurgitation on either their initial or their predischarge ventriculogram. The proportion of infarct-related arteries found to be patent (TIMI flow grade 2 or 3) was statistically similar in patients with and without mitral regurgitation during each angiographic evaluation period (initial, 90 min and 10 days). Although coronary artery perfusion increased overall during sequential measurement (mean TIMI grade was 0.4 +/- 0.6 initially, 1.5 +/- 1.3 at 90 min and 2.2 +/- 1.0 at 10 days), the pattern of reperfusion observed could not predict an increase or decrease in regurgitant severity (p = NS). Early mitral regurgitation resolved in 57% of patients by 10 days, but this resolution appeared independent of the presence or absence of improved coronary perfusion (60% vs. 50%). The development of new regurgitation during the recovery period (6%) was also unrelated to improved perfusion (7% vs. 4%).

CONCLUSIONS

Acute mitral regurgitation developing during myocardial infarction shows frequent changes in its presence or severity during the 1st 10 days, appears independent of coronary artery patency both early and late after thrombolysis and cannot be reliably treated by improving arterial perfusion with thrombolytic agents.

Lumen diameter of normal human coronary arteries. Influence of age, sex, anatomic variation, and left ventricular hypertrophy or dilation

BACKGROUND

Precise knowledge of the expected "normal" lumen diameter at a given coronary anatomic location is a first step toward developing a quantitative estimate of coronary disease severity that could be more useful than the traditional "percent stenosis."

METHODS AND RESULTS

Eighty-three arteriograms were carefully selected from among 9,160 consecutive studies for their smooth lumen borders indicating freedom from atherosclerotic disease. Of these, 60 men and 10 women had no abnormalities of cardiac function, seven men had idiopathic dilated cardiomyopathy, and six men had left ventricular hypertrophy associated with significant aortic stenosis. Lumen diameter was measured at 96 points in 32 defined coronary segments or major branches. Measurements were scaled to the catheter, corrected for imaging distortion, and had a mean repeat measurement error of 0.12 mm. When sex, anatomic dominance, and branch length were accounted for, normal lumen diameter at each of the standard anatomic points could usually be specified with a population variance of +/- 0.6 mm or less (SD) and coefficient of variation of less than 0.25 (SD/mean). For example, the left main artery measured 4.5 +/- 0.5 mm, the proximal left anterior descending coronary artery (LAD) 3.7 +/- 0.4 mm, and the distal LAD 1.9 +/- 0.4 mm. For the LAD, lumen diameter was not affected by anatomic dominance (right versus left), but for the right coronary artery, proximal diameter varied between 3.9 +/- 0.6 and 2.8 +/- 0.5 mm (p less than 0.01) and for the left circumflex, between 3.4 +/- 0.5 and 4.2 +/- 0.6 mm (p less than 0.01). Women had smaller epicardial arterial diameter than men (-9%; p less than 0.001), even after normalization for body surface area (p less than 0.01). Branch artery caliber was unaffected by the anatomic dominance but increased with branch length, expressed as a fraction of the origin-to-apex distance (p less than 0.001). Lumen diameter was not affected by age or by vessel tortuosity but was significantly increased among men with left ventricular hypertrophy (+ 17%; p less than 0.001) or dilated cardiomyopathy (+ 12%; p less than 0.001).

CONCLUSIONS

This is a reference normal data set against which to compare lumen dimensions in various pathological states. It should be of particular value in the investigation of diffuse atherosclerotic disease.

Mitral regurgitation in early myocardial infarction. Incidence, clinical detection, and prognostic implications. TIMI Study Group

OBJECTIVE

To investigate mitral regurgitation occurring early in the course of acute myocardial infarction with respect to its incidence, the impact of infarct size and location, the accuracy of clinical detection, the contribution of global and regional left ventricular performance, and its influence on prognosis.

DESIGN

Prospective observational study derived from patients entering Phase I of the Thrombolysis in Myocardial Infarction (TIMI) trial.

SETTING

Multicenter trial involving 13 university-affiliated medical centers.

PATIENTS

A total of 206 patients studied within 7 hours of symptom onset during their first myocardial infarction.

MEASUREMENTS

Contrast left ventriculography was used to document mitral regurgitation.

RESULTS

Mitral regurgitation was present in 27 patients (13%). Although the presence of regurgitation correlated with the site of infarction (20 of 27 had anterior infarctions) and the number of akinetic chords, it was not statistically related to the peak creatine kinase value or to left ventricular chamber size or filling pressure. A murmur of mitral regurgitation was heard in only 2 patients (1 incorrectly). The presence of early mitral regurgitation predicted cardiovascular mortality at 1 year by univariate (relative risk, 12.2; 95% Cl, 3.5 to 42; P less than 0.0001) and multivariate (relative risk, 7.5; Cl, 2.0 to 28.6; P = 0.0008) analyses.

CONCLUSIONS

Mitral regurgitation in early myocardial infarction is generally clinically "silent," is more common in anterior infarction, is associated with regional dysfunction but not early ventricular dilation or peak enzyme release, and is an important predictor of cardiovascular mortality.

Regression of coronary artery disease as a result of intensive lipid-lowering therapy in men with high levels of apolipoprotein B

BACKGROUND AND METHODS

The effect of intensive lipid-lowering therapy on coronary atherosclerosis among men at high risk for cardiovascular events was assessed by quantitative arteriography. Of 146 men no more than 62 years of age who had apolipoprotein B levels greater than or equal to 125 mg per deciliter, documented coronary artery disease, and a family history of vascular disease, 120 completed the 2 1/2-year double-blind study, which included arteriography at base line and after treatment. Patients were given dietary counseling and were randomly assigned to one of three treatments: lovastatin (20 mg twice a day) and colestipol (10 g three times a day); niacin (1 g four times a day) and colestipol (10 g three times a day); or conventional therapy with placebo (or colestipol if the low-density lipoprotein [LDL] cholesterol level was elevated).

RESULTS

The levels of LDL and high-density lipoprotein (HDL) cholesterol changed only slightly in the conventional-therapy group (mean changes, -7 and +5 percent, respectively), but more substantially among patients treated with lovastatin and colestipol (-46 and +15 percent) or niacin and colestipol (-32 and +43 percent). In the conventional-therapy group, 46 percent of the patients had definite lesion progression (and no regression) in at least one of nine proximal coronary segments; regression was the only change in 11 percent. By comparison, progression (as the only change) was less frequent among patients who received lovastatin and colestipol (21 percent) and those who received niacin and colestipol (25 percent), and regression was more frequent (lovastatin and colestipol, 32 percent; niacin and colestipol, 39 percent; P less than 0.005). Multivariate analysis indicated that a reduction in the level of apolipoprotein B (or LDL cholesterol) and in systolic blood pressure, and an increase in HDL cholesterol correlated independently with regression of coronary lesions. Clinical events (death, myocardial infarction, or revascularization for worsening symptoms) occurred in 10 of 52 patients assigned to conventional therapy, as compared with 3 of 46 assigned to receive lovastatin and colestipol and 2 of 48 assigned to receive niacin and colestipol (relative risk of an event during intensive treatment, 0.27; 95 percent confidence interval, 0.10 to 0.77).

CONCLUSIONS

In men with coronary artery disease who were at high risk for cardiovascular events, intensive lipid-lowering therapy reduced the frequency of progression of coronary lesions, increased the frequency of regression, and reduced the incidence of cardiovascular events.

Variables predictive of good functional outcome following thrombolytic therapy in the Thrombolysis in Myocardial Infarction phase II (TIMI II) pilot study

Before commencing the randomized Thrombolysis in Myocardial Infarction phase II (TIMI II) study, 370 patients were administered intravenous recombinant tissue plasminogen activator (rt-PA) within 4 hours of onset of acute myocardial infarction (AMI) and assigned to 2-hour (immediate) percutaneous transluminal angioplasty (n = 33), 18- to 48-hour (delayed) angioplasty (n = 288) or no angioplasty (n = 49) in a nonrandomized, observational pilot study. Left ventricular ejection fraction at rest and during exercise was assessed by gated equilibrium radionuclide ventriculography at hospital discharge and again at 6 weeks. At hospital discharge, ejection fraction averaged 50% at rest and 56% at peak exercise. At 6-week follow-up, ejection fraction averaged 50% at rest and 53% at peak exercise. At 6-week follow-up, resting ejection fraction average 49% in the 2-hour angioplasty group, 49% in the 18- to 48-hour angioplasty group and 55% in the no-angioplasty group. Variables independently predicting "good functional outcome" at 6-week follow-up (survival with resting ejection fraction greater than equal to 50% and no decrease with exercise) in the 18- to 48-hour angioplasty group were fewer leads with ST-segment elevation greater than or equal to 0.1 mV, younger age, rapid normalization during rt-PA infusion of ST segments or dramatic relief of chest pain, absence of arrhythmias within the first 24 hours of treatment initiation, no prior infarction and not a cigarette smoker at entry. Thus, the TIMI II pilot study demonstrates that most patients with AMI of less than or equal to 4-hour duration treated with rt-PA have good ventricular function after AMI.(ABSTRACT TRUNCATED AT 250 WORDS)

Progression of coronary atherosclerosis in patients with probable familial hypercholesterolemia. Quantitative arteriographic assessment of patients in NHLBI type II study

A computer-assisted method for quantitatively assessing progression and regression of coronary atherosclerosis has been applied, in a fully blinded fashion, to a set of 116 5-year-interval coronary arteriograms obtained between 1972 and 1981 in the National Heart, Lung, and Blood Institute (NHLBI) Type II Study. Coronary changes are described in 54 of these patients who had tendinous xanthomata and hypercholesterolemia consistent with the diagnosis of familial hypercholesterolemia. Among 468 patent lesions of all degrees of severity and among 25 total occlusions identified on the initial arteriogram, 11% progressed by the 95% confidence criterion for assessing change in percent stenosis (+/- 17%), and 1% regressed by using the same criterion. Among 54 patients, 50% had progression only, 6% had regression only, and 4% had mixed progression and regression. Because half of these patients were treated with cholestyramine, these frequencies may underestimate the natural history of their disease progression. Comparable frequencies were obtained by using the 95% confidence criterion for change in stenosis resistance (Rp ratio outside range, 0.35 to 2.9). In properly obtained arteriograms, the Rp parameter is physiologically relevant and is a sensitive index of lesion change with a high signal-to-noise ratio; we advocate its use for detection of progression and regression. Morphologic features, including luminal irregularity and ulceration, increased the likelihood of progression by 1.8- to 5-fold. Surprisingly, significant arterial flexing at the site of the lesion predicted anatomic stability. A lumen narrowed by visible thrombus was 100-fold more likely to regress than were those without it. The initial severity of stenosis correlated strongly with new total occulusion and with disease progression as assessed by Rp change. Because lesion-specific features are important determinants of lesion change, intervention trials that statistically account for the contributions of lesion morphology are likely to provide a more insightful assessment of the therapeutic benefit.

Intrathoracic spatial location of specified coronary segments on the normal human heart. Applications in quantitative arteriography, assessment of regional risk and contraction, and anatomic display

The clinically important coronary segmental anatomy has been described in a format useful for quantitative analysis and standardized display. We have determined the intrathoracic location and course of each of the 23 coronary artery segments and branches commonly used for clinical description of disease. Measurements were averaged from perpendicular angiographic view-pairs in 37 patients with normal-sized hearts. Each segment or branch is described by several points along its course; each point is specified in polar coordinates as the radial distance from the principal coronary ostium and by angles about the patient, corresponding to those describing rotation in c-arm radiographic systems. This computer-assisted measurement method is accurate to within +/- 0.2 cm (SD) and +/- 2 degrees in phantom studies. Coronary segment location among a group of normal-sized hearts can be specified to within +/- 1.0 cm (SD). For example, the left anterior descending coronary artery segment at the apex of the heart is 12.2 +/- 1.0 cm from the left coronary ostium, 32 +/- 4 degrees to the left of the anterioposterior axis, and at 46 +/- 7 degrees of caudal angulation. There are several clinically important applications of this new knowledge. First, this anatomic format provides the basis for estimating regional myocardial contraction and the relative size of the myocardial region at risk from a given arterial occlusion. Second, precise knowledge of "normal" segment location greatly simplifies the computation of dimensional correction factors for quantitative arteriography. Third, viewing angles most appropriate for videodensitometric assessment of lesion lumen area may be computed from these data. The theoretical basis and numerical values needed for most of the above estimates are provided. Finally, a computer program has been written to generate a three-dimensional tree-branch vascular model from these anatomic locations. This easily used interactive program aids in teaching coronary angiographic anatomy and, of importance, permits selection of viewing angles that "best" visualize the traditionally difficult parts of the coronary tree.

Early recovery of left ventricular function after thrombolytic therapy for acute myocardial infarction: an important determinant of survival

Thrombolytic therapy for acute myocardial infarction reduces early mortality, but full recovery of left ventricular function after reperfusion is delayed. Therefore, the relations among reperfusion, survival and the time course of left ventricular functional recovery were examined in 226 patients treated with intracoronary streptokinase; 77% (134 patients) had sustained reperfusion and 31 patients had no reperfusion or had reocclusion by day 3. Wall motion was measured from contrast ventriculograms performed in the acute period and 3 days later in the central and peripheral infarct regions and the noninfarct region by the centerline method in 165 patients. Patients with reperfusion had better survival (p less than 0.05, mean follow-up 4.5 years) and a higher ejection fraction at 3 days (52 +/- 12 versus 46 +/- 10%, p less than 0.02) attributable to a significantly different change in peripheral infarct region function between the acute and 3 day studies (0.1 +/- 1.0 versus -0.3 +/- 0.9 SD, p less than 0.05). These early functional changes were significant in patients with anterior myocardial infarction and showed similar trends in those with inferior myocardial infarction. On Cox regression analysis, function measured at 3 days was more predictive of survival than was function measured acutely (chi square for acute ejection fraction = 11.48 versus 24.59 at 3 days). Although, as previously reported, greater than 45% of total recovery of left ventricular function occurs later, the ejection fraction achieved by day 3 is already predictive of survival. Thus, the mechanism by which successful thrombolytic therapy enhances survival is improvement of regional and global left ventricular function early after acute myocardial infarction.

Treatment of type III hyperlipoproteinemia with gemfibrozil to retard progression of coronary artery disease

Eight type III hyperlipoproteinemic (type III HLP), homozygous E 2/2 patients were enrolled in two periods of long-term diet-gemfibrozil treatment. The combined therapy resulted in highly significant decreases in their low-density lipoprotein cholesterol, very-low density lipoprotein cholesterol, very-low density lipoprotein triglycerides, and increases in their high-density lipoprotein cholesterol during the first treatment period of 24 to 28 months. Type III HLP reasserted itself following an 8-week interruption of gemfibrozil therapy. Resumption of gemfibrozil therapy again lowered the high lipid-lipoprotein concentrations of these patients toward normal. Tuboeruptive xanthomata, palmar xanthoma, and xanthoma striata palmare subsided with treatment. Follow-up coronary arteriograms performed 2.5 to 3.0 years after initiation of diet-drug treatment showed stabilization of coronary arterial lesions, which was associated with improvement in exercise tolerance.

Improved survival up to four years after early coronary thrombolysis

The long-term prognosis after thrombolytic therapy in patients with acute myocardial infarction (AMI) is unknown. This question was investigated in a 4-year follow-up study of 227 patients. According to the status of reperfusion at the end of the acute catheterization, the patients were divided into a patent (n = 171) and an occluded (n = 56) group. Both hospital and 4-year mortality rates were significantly reduced in the patent group by 13 and 14%, respectively (p less than or equal to 0.005 for both). Baseline variables known to be important for prognosis did not differ between the 2 groups. Patients with a patent infarct artery who underwent early acute coronary artery bypass grafting (CABG) had a greater survival (p less than 0.10) and better left ventricular function (p less than 0.01) than did patients with a patent infarct artery who did not undergo CABG. This difference was associated with a lower frequency of fatal reinfarction and cardiogenic shock in the CABG group. Thus, survival is improved up to 4 years after successful thrombolysis and appears to be further enhanced by early CABG.

Use of a satellite-assisted computer link for long-distance research collaboration

Research collaboration between investigators located at some distance from each other is not only possible but also feasible. By using satellite-assisted computer-to-computer links, researchers across the United States and overseas work with the staff and facilities of the Cardiovascular Research and Training Center (CVRTC) in the University of Washington, Seattle. This report presents the mechanics, advantages, and results of using such an approach to collaborate with distant colleagues.

Percutaneous transluminal coronary angioplasty and subsequent restenosis: quantitative and qualitative methodology for their assessment

Coronary arteriography is the most commonly used technique for documenting the immediate percutaneous transluminal coronary angioplasty result and for follow-up of the dilated arterial segment for restenosis within 6 months (which occurs in about 25% to 35% of cases). Acute success in dilation of the coronary lesion is likely if there is at least a resultant 1.3 mm2 minimum lumen area, equivalent to a 1.3 mm mean minimum lumen diameter, or about a 50% diameter stenosis of a typical proximal vessel. The measurement methods applied to this problem include a digital caliper, computer-assisted border recognition techniques and a video-densitometric approach to estimation of lumen area. Calipers are recommended because of their simplicity, precision and accuracy for the routine assessment of angioplasty result. Border-recognition techniques require considerable operator input to distinguish true flow channels from cul de sacs in the dissected segment. The automated scanning videodensitometry approach has theoretical appeal and has shown promise in preliminary reports; however, there is the potential for large measurement errors in the setting of dissection. Further, certain qualitative morphologic features of the dilated segment, such as longitudinal or transverse dissection or intraluminal thrombus, may effectively contribute to the prediction of acute complications and may be useful predictors of late restenosis. Because these features are best appreciated at increased arteriographic magnification, further high resolution studies will be necessary to better understand their importance.

Thrombolysis in Myocardial Infarction (TIMI) Trial, Phase I: A comparison between intravenous tissue plasminogen activator and intravenous streptokinase. Clinical findings through hospital discharge

Intravenous administration of 80 mg of recombinant tissue plasminogen activator (rt-PA, 40, 20, and 20 mg in successive hours) and streptokinase (SK, 1.5 million units over 1 hr) was compared in a double-blind, randomized trial in 290 patients with evolving acute myocardial infarction. These patients entered the trial within 7 hr of the onset of symptoms and underwent baseline coronary arteriography before thrombolytic therapy was instituted. Ninety minutes after the start of thrombolytic therapy, occluded infarct-related arteries had opened in 62% of 113 patients in the rt-PA and 31% of 119 patients in the SK group (p less than .001). Twice as many occluded infarct-related arteries opened after rt-PA compared with SK at the time of each of seven angiograms obtained during the first 90 min after commencing thrombolytic therapy. Regardless of the time from onset of symptoms to treatment, more arteries were opened after rt-PA than SK. The reduction in circulating fibrinogen and plasminogen and the increase in circulating fibrin split products at 3 and 24 hr were significantly less in patients treated with rt-PA than in those treated with SK (p less than .001). The occurrence of bleeding events, administration of blood transfusions, and reocclusion of the infarct-related artery was comparable in the two groups. Thus, in patients with acute myocardial infarction, rt-PA elicited reperfusion in twice as many occluded infarct-related arteries as compared with SK at each of seven serial observations during the first 90 min after onset of treatment.

The effect of intravenous thrombolytic therapy on left ventricular function: a report on tissue-type plasminogen activator and streptokinase from the Thrombolysis in Myocardial Infarction (TIMI Phase I) trial

In Phase I of the NHLBI trial of Thrombolysis in Myocardial Infarction (TIMI), 290 patients admitted within 7 hr after onset of acute infarction were randomly assigned to intravenous treatment with either streptokinase (SK) or recombinant tissue-type plasminogen activator (rt-PA). Left ventricular function was measured from contrast ventriculograms in 145 patients with both pretreatment and predischarge studies analyzable. Regional wall motion in the infarct site was measured by the centerline method and expressed in units of standard deviations (SDs) from the mean motion in 52 normal subjects. Patients treated with rt-PA (n = 77) achieved a significantly higher reperfusion rate after 90 min of treatment. Perfusion of the infarct-related artery improved from visual grade 0 or 1 (total occlusion or penetration without perfusion) to grade 2 or 3 (partial or full reperfusion) in 62% receiving rt-PA vs 31% receiving SK (n = 68) (p less than .001). However, the ejection fraction did not change significantly from before treatment to before discharge in either treatment group (+0.7 +/- 6.7% vs +1.0 +/- 8.3%, respectively). A small but significant increase in regional wall motion was observed in each of the two groups (+0.4 +/- 0.8 vs +0.3 +/- 0.8 SD/chord, respectively; each p less than .001 compared with baseline). This was countered by declines in the hyperkinesis of the noninfarct region (-0.3 +/- 1.0 SD/chord [p = .01] compared with baseline and -0.2 +/- 1.0 SD/chord [p = .23], respectively). Analysis of the combined groups revealed that the ejection fraction increased only in patients who achieved reperfusion by 90 min after onset of therapy or who had subtotal occlusions initially. There was greater recovery of left ventricular function in patients who achieved reperfusion earlier vs later than 4 hr after symptom onset and in patients with vs without some collateral circulation to the infarct-related artery.

Usefulness of recanalization to luminal diameter of 0.6 millimeter or more with intracoronary streptokinase during acute myocardial infarction in predicting "normal" perfusion status, continued arterial patency and survival at one year

To determine whether arteriographic dimensions of the acutely recanalized coronary lumen provide information about regional perfusion or clinical outcome, quantitative arteriography was used to measure minimum luminal diameter achieved with intracoronary streptokinase administration in 44 patients with acute myocardial infarction (AMI). Degree of coronary reperfusion was independently assessed visually using the criteria applied in the multicenter Thrombolysis in Myocardial Infarction study. Minimum diameter and qualitative reperfusion grade were both assessed from 172 coronary injections during thrombolysis. Partial perfusion (grade 1 or 2) was seen in 95 of 135 injections (70%) in which the minimum diameter was less than 0.6 mm and complete perfusion (grade 3) was seen in 35 of 37 injections (95%) in which it was 0.6 mm or more (p less than 0.001). Repeat cardiac catheterization was performed at 5.5 +/- 4.9 weeks after AMI (n = 20). When vessels were opened acutely to a minimum diameter of less than 0.6 mm, 5 of 12 vessels (42%) were reoccluded at the time of restudy and 8 of 29 patients (28%) died within 12 months. By contrast, 0 of 8 vessels (0%) were reoccluded when the artery was opened to a diameter of at least 0.6 mm (difference not significant), and only 1 of 15 patients (7%) died (p less than 0.05). Of the patients with grade 1 o r 2 perfusion at the end of the thrombolytic infusion, 7 of 19 (37%) died within 12 months and 2 of 4 vessels (50%) reoccluded; of the patients with grade 3 perfusion, 2 of 25 (8%) died (p less than 0.05) and 2 of 16 vessels (13%) reoccluded (difference not significant).(ABSTRACT TRUNCATED AT 250 WORDS)

Should airline pilots be eligible to resume active flight status after coronary bypass surgery?: a CASS registry study

Medical certification to return to work after coronary bypass surgery in occupations that carry a risk to public safety is controversial, particularly for airline pilots. To address this issue, 10,312 patients from the CASS registry who underwent coronary bypass surgery were studied and 2,326 men with clinical and postoperative characteristics similar to those of the average airline pilot who might apply to renew his license after surgery were selected. The 5 year probability of remaining free of an acute cardiac event, defined as acute coronary insufficiency, myocardial infarction or sudden death, was 0.92 +/- 0.01 (mean +/- SE) for the 1,207 men without previous myocardial infarction and 0.98 +/- 0.01 for the 122 men who never smoked and did not have a history of hypertension. Among the 1,119 men with a previous myocardial infarction, the probability of remaining free of acute cardiac events was 0.91 +/- 0.02 and 0.92 +/- 0.02 when left ventricular contraction score was 5 to 9 and 10 or greater, respectively. In this patient subgroup, mortality rate was similar to that of the age-matched U.S. male population when the left ventricular contraction score was 5 to 9 (4.0% versus 4.3%; p = NS) but significantly worse when the left ventricular contraction score was 10 or greater (7% versus 4.2%; p = 0.05). The data from this CASS registry study are pertinent to the question of operationally unlimited first-class medical certification of carefully selected airline pilots after coronary bypass surgery.(ABSTRACT TRUNCATED AT 250 WORDS)

Measurement of regional wall motion from biplane contrast ventriculograms: a comparison of the 30 degree right anterior oblique and 60 degree left anterior oblique projections in patients with acute myocardial infarction

The value of performing biplane vs single plane analysis of regional wall motion from contrast ventriculograms was determined in 102 patients who received thrombolytic therapy and who underwent biplane ventriculography during acute myocardial infarction (n = 67), at follow-up more than 2 weeks later (n = 80), or both (n = 45). Hypokinesis in the infarct region and hyperkinesis in the noninfarct region were measured by the centerline method in the respective artery territories, which were defined from the data of 62 patients with single-vessel disease and were expressed in units of standard deviations from the mean of 32 normal subjects. Hypokinesis was more severe and extended over a longer segment of the left ventricular contour when measured in the right anterior oblique (RAO) projection in thrombosis of the left anterior descending coronary artery (LAD) but more severe and extensive in the left anterior oblique (LAO) projection in circumflex stenosis. Hyperkinesis opposite the LAD or the circumflex was greater in the LAO projection. In patients with thrombosis of the right coronary artery, wall motion abnormalities were similar in the two projections. Thus the evaluation of hypokinesis caused by acute coronary thrombosis and of the effect of therapeutic interventions in salvaging function can be adequately evaluated from single-plane 30 degree RAO ventriculograms, except in the small minority of patients with circumflex thrombosis.

Advantages and applications of the centerline method for characterizing regional ventricular function

We sought to identify theoretical advantages and applications of the centerline method for quantitative assessment of regional ventricular function. Motion was measured along 100 chords constructed perpendicular to a centerline drawn midway between the end-diastolic and end-systolic contours, and normalized for heart size. Abnormality was expressed in units of standard deviations from the mean motion in a normal reference population to indicate both the severity and significance of the wall motion abnormality. The mean abnormality averaged over 100 chords correlated highly with the area ejection fraction (r = .97). The centerline method uses a "sliding window" to measure motion where it is abnormal, because assessment of wall motion in predefined regions of the ventricular contour underestimates abnormality. From the 100 data points, the extent (% of contour) of regional abnormalities can also be determined. The severity of hypokinesis at the site of acute myocardial infarction correlated better with infarct size estimated from creatine kinase release (r = -.78) than did the ejection fraction or the circumferential extent of hypokinesis. Because the centerline method measures motion along locally determined vectors, and requires no apex, origin, coordinate system, or geometric reference figure, it can be applied to contours as dissimilar as the 60 degree left anterior oblique projection of the left ventricle and the 75 degree left anterior oblique projection of the right ventricle.

Hyperemic myocardial perfusion imaging for noninvasive detection of coronary disease in man: comparison of treadmill exercise and intravenous dipyridamole infusion

To further understand hyperemic myocardial perfusion imaging, the effects of exercise and intravenous dipyridamole on coronary flow, coronary stenosis luminal area, stenosis flow resistance, and regional myocardial perfusion were evaluated in patients with arteriographically documented coronary artery disease. Coronary hemodynamics were assessed in 24 patients undergoing routine diagnostic catheterization. Coronary flow was measured by coronary sinus thermodilution. Computer assisted stenosis measurements were made. During isometric handgrip coronary sinus flow increased to 1.7 X baseline value, and epicardial coronary arteries constricted to increase predicted stenosis flow resistance by 40%. A 4-minute intravenous dipyridamole infusion (0.56 mg/kg) increased coronary sinus flow to 2.4 X baseline with, on average, no change in the stenotic coronary lumen diameter. During simultaneous isometric handgrip and dipyridamole infusion coronary sinus flow increased to 3.3 X baseline value and stenosis flow resistance increased an average of 36%. Regional myocardial perfusion was assessed in 33 patients by thallium201 myocardial perfusion imaging following maximal treadmill exercise and again following intravenous dipyridamole infusion. Regional thallium201 imaging effects were correlated with measurements of angiographic coronary disease. Sensitivity and specificity for detecting a greater than or equal to 50% stenosis were 85% and 64% (p less than .005), respectively, for dipyridamole and 84% and 68% (p less than .005) for exercise thallium201. In summary, coronary blood flow increases with isometric exercise and is near maximal following intravenous dipyridamole. Quantitative arteriographic techniques demonstrate isometric exercise-induced constriction of coronary stenoses and increased stenosis flow resistance. Stenosis flow resistance increases following intravenous dipyridamole only for severe (greater than or equal to 65%) lesions. Treadmill exercise and intravenous dipyridamole are comparably effective hyperemic stimuli for creating regional perfusion differences for the noninvasive detection of coronary disease.(ABSTRACT TRUNCATED AT 250 WORDS)

Incomplete lysis of thrombus in the moderate underlying atherosclerotic lesion during intracoronary infusion of streptokinase for acute myocardial infarction: quantitative angiographic observations

Thrombolytic recanalization of the obstructed coronary lumen was studied in 32 patients receiving intracoronary streptokinase for 60 to 90 min during acute myocardial infarction. The process was viewed at high arteriographic magnification and was quantified with computer-assisted measurements from repeated single-plane views. The variability of the method for this application was 0.15 to 0.18 mm on minimum diameter estimates. Structural details were seen that are not commonly appreciated at conventional magnification. The recanalized lumen appears to form along an interface between the thrombus and the vessel wall, progressively enlarging its minimum arteriographic diameter to 0.65 +/- 0.24 mm (+/- 1 SD) at the end of the short-term infusion of streptokinase reflecting a final percent stenosis of 77 +/- 10%. In nine infarct lesions found patent 5 +/- 3 weeks later, the recanalized lumen further improved an average of 0.34 mm in minimum diameter (p less than .005) and 13% stenosis (p less than .01). A thin film of contrast medium surrounding the obstructing thrombus faintly defined the boundaries of the original atherosclerotic lumen in all but two cases. The "original stenosis" measured 1.25 +/- 0.32 mm in minimum diameter and 56 +/- 14% stenosis when first visualized; it was unchanged throughout the course of infusion of streptokinase. In five patients catheterized 10 +/- 12 weeks before their infarction, the original stenosis averaged 1.15 +/- 0.22 mm in the preinfarct angiogram, as compared with 1.17 +/- 0.23 mm in its faintly defined form during thrombolytic therapy (p = NS). In 10 cases, this original lesion was less than a 50% stenosis, and in 21 cases less than 60%.(ABSTRACT TRUNCATED AT 250 WORDS)

Intravenous recombinant tissue-type plasminogen activator in patients with acute myocardial infarction: a report from the NHLBI thrombolysis in myocardial infarction trial

The efficacy and safety of a 3 hr, 80 mg intravenous infusion of recombinant tissue-type plasminogen activator (rt-PA) were investigated in 47 patients with acute myocardial infarction. Coronary angiography, performed before the administration of rt-PA and for 90 min thereafter, demonstrated that 37 patients had total coronary occlusion before therapy. After 90 min of rt-PA (50 mg), reperfusion of the infarct-related artery was observed in 25 patients (68%). Continuous infusions of heparin for anticoagulation were administered for 8 to 10 days. Of 36 patients who underwent follow-up coronary cineangiography, 21 had initially presented with total occlusion and had experienced reperfusion at 90 min. Sustained perfusion of the infarct-related artery was observed in 14 (67%) of these 21 initially reperfused patients. Late angiography was performed in nine patients who initially demonstrated subtotal occlusion of the infarct-related artery; sustained perfusion was observed in eight (89%). Significant bleeding was observed in 15 patients (32%). A hematoma at the site of the acute catheterization accounted for most instances of significant bleeding (11/15, 73%). Administration of rt-PA resulted in a significant decline in fibrinogen and plasminogen while amounts of fibrin(ogen) degradation products rose. In no patient, however, did fibrinogen levels decline to less than 140 mg/dl. Thus, rt-PA, administered as a brief 80 mg intravenous infusion, is capable of restoring blood flow in a high proportion of patients with acute myocardial infarction due to total coronary obstruction. Declines in plasma fibrinogen and plasminogen are observed. If combined with heparin anticoagulation and invasive vascular procedures, significant bleeding is a common complication.(ABSTRACT TRUNCATED AT 250 WORDS)

Usefulness of coronary artery bypass graft surgery or percutaneous transluminal angioplasty after thrombolytic therapy

Intracoronary streptokinase (STK) was given to 52 patients and 2 million U of intravenous urokinase was given to 15 patients with acute myocardial infarction less than 3 hr from onset of symptoms. Wall motion in the infarct region improved in 20 patients receiving STK alone (-2.5 +/- 1 to 2.1 +/- 1.1 SD/chord) and in 22 patients receiving STK and undergoing coronary bypass surgery within 24 hr (-2.5 +/- 1 to -1.5 +/- 1.0 SD/chord). Wall motion was unchanged in 10 patients not successfully reperfused with STK (-2.9 +/- 0.7 to -3.1 +/- 0.7 SD/chord). Regional wall motion improved at least 1.0 SD/chord in 71% of 14 patients treated within 2 hr of onset of symptoms, but in only 29% of 34 treated after 2 hr. Mean coronary artery stenosis after thrombolysis was 77 +/- 9%. Rethrombosis was associated with a stenotic cross-sectional area of less than 0.4 mm2. Ventricular function did not improve, with a residual stenosis of 0.4 mm or less in diameter. The Western Washington randomized trial reported a 1 year mortality of 2.5% in 80 successfully reperfused patients, but a mortality of 23% in 13 in whom reperfusion was partial and of 14.6% in 41 in whom reperfusion failed. The improved survival with successful reperfusion and improved ventricular performance with early and more complete reperfusion has stimulated interest in the need for angioplasty and coronary artery bypass grafting after thrombolytic therapy.

High dose intravenous streptokinase for acute myocardial infarction: preliminary results of a multicenter trial

To assess the efficacy of intravenous streptokinase in patients with acute myocardial infarction, 40 patients (30 men and 10 women, mean age 54 years) with acute myocardial infarction were given 1.5 million U of streptokinase intravenously in 1 hour, and coronary arteriography was performed repeatedly to assess reperfusion. Streptokinase treatment was begun 270 +/- 86 (mean +/- SD) minutes after the onset of chest pain. Of the 40 patients, 34 had total or near total coronary occlusion before streptokinase administration. In 14 (41%) of these 34 patients, some reperfusion occurred during the 90 minutes after the administration of streptokinase, but in only 11 of the 14 was reperfusion present at 90 minutes. After streptokinase administration, all patients received heparin for 8 to 10 days; they were subsequently administered aspirin and dipyridamole. Clinical evidence of reocclusion during the first 24 hours of heparin therapy occurred in one patient. Thus, when given to patients with acute myocardial infarction and total coronary occlusion an average of 4 1/2 hours after the onset of chest pain, high dose intravenous streptokinase achieves reperfusion in only about 40% and results in sustained reperfusion in only about 30%.

Coronary artery dilation and hemodynamic responses after isosorbide dinitrate therapy in patients with coronary artery disease

The response to sublingual isosorbide dinitrate (ISDN) was studied in 10 men with suspected coronary artery disease undergoing coronary arteriography. A Swan-Ganz catheter was placed in the pulmonary artery to record hemodynamic response. Diseased coronary segments were identified during routine Judkins selective coronary angiograms. Sublingual isosorbide dinitrate (ISDN) (5 or 10 mg) was then given with the catheters in place. Multiple sequential single-view coronary angiograms and pulmonary and systemic hemodynamic responses were recorded over 30 minutes after drug administration. At 30 minutes, there was a 53% reduction (p less than 0.01) in pulmonary capillary wedge pressure and a 15% decrease (p less than 0.05) in systemic and pulmonary vascular resistance, with a net 13% decrease (p less than 0.01) in cardiac output and 20% decrease (p less than 0.01) in mean arterial pressure. Quantitative arteriography demonstrated substantial dilation of luminal cross-sectional area in both normal and diseased coronary arterial segments. Normal epicardial segments were grouped according to luminal area (1 to 4, 4 to 8 and more than 8 mm2) and demonstrated maximal area dilation at 10 minutes of 55% (p less than 0.01), 29% (p less than 0.01) and 16% (p less than 0.05), respectively. Diseased epicardial segments (stenosis 50% or greater) dilated 51% (p less than 0.01) at 10 minutes. Calculated stenosis resistance decreased 40% (p less than 0.01). Diseased segments in small and middle-sized arteries (1 to 8 mm2) are 4 times more reactive than those in larger arteries (more than 8 mm2), with peak dilation of 77 vs 21% (p less than 0.01) at 30 minutes.(ABSTRACT TRUNCATED AT 250 WORDS)

Time from onset of symptoms to thrombolytic therapy: a major determinant of myocardial salvage in patients with acute transmural infarction

To determine whether myocardial salvage after successful intracoronary or intravenous thrombolysis is time dependent, the relation between left ventricular wall motion and the time to treatment was studied in 69 patients admitted less than 3 hours after onset of acute transmural myocardial infarction (42 patients with reperfusion by intracoronary streptokinase, 27 by intravenous urokinase). A similar significant relation between the time to treatment and the severity of regional hypokinesia at follow-up was found in the intracoronary and intravenous groups. To better define this relation, particularly during the early phase of infarction, the groups were combined. In patients in whom thrombolytic treatment was initiated within 2 hours after symptom onset, wall motion at follow-up was within 2 standard deviations of the normal mean in 82% (14 of 17 patients). If treatment was started 2 to 5 hours after symptom onset, the probability of improved wall motion decreased to 46% (24 of 52 patients, p less than 0.025). The time/wall motion relation appeared to be independent of infarct location, angiographically visible collateral vessels and the presence of subtotal coronary artery occlusion. The severity of hypokinesia at follow-up study correlated with the magnitude of peak serum creatine kinase (r = -0.71), indicating that thrombolytic therapy initiated within 2 hours after the onset of symptoms improves regional left ventricular function and reduces infarct size more than later therapy does.

Factors that determine recovery of left ventricular function after thrombolysis in patients with acute myocardial infarction

The coronary and ventricular angiograms of 47 patients with acute myocardial infarction in whom reperfusion was achieved by intracoronary streptokinase were quantitatively analyzed to determine the factors that affect recovery of regional left ventricular function after reperfusion. Hypokinesis in the infarct region was measured by the centerline method and expressed in terms of standard deviations (SDs) from normal. Severity of coronary artery stenosis was measured quantitatively. Hypokinesis showed more significant improvement after thrombolysis in patients with minimum stenosis diameter of greater than 0.4 mm than in those with severe residual stenosis, i.e., stenosis producing a minimum diameter of 0.4 mm or less (1.0 +/- 1.3 SD/chord, n = 31, vs 0.0 +/- 0.9 SD/chord, n = 7; p less than .05). Improvement in hypokinesis was greater in patients who received thrombolytic therapy within 2 hr than in those treated later (2.1 +/- 1.1, n = 8, vs 0.7 +/- 1.0 SD/chord, n = 28; p less than .001). These results indicate that angiographic reperfusion alone may not be sufficient: reperfusion must provide adequate flow and be achieved early to salvage myocardial function.

Intravenous urokinase in acute myocardial infarction

To achieve reperfusion early, an intravenous bolus of 2 million units of urokinase was administered in 50 patients with transmural acute myocardial infarction (AMI) 1.8 +/- 2.5 hours after the onset of symptoms. Coronary angiography performed 1.1 +/- 0.6 hours after urokinase therapy revealed patent coronary arteries in 30 patients (60%), with no significant difference between those with anterior and those with inferior AMI. Reocclusion occurred in only 1 of 24 patients restudied. Failure to achieve reperfusion was not related to the degree of systemic fibrinolytic activity, which was equally high in patients who did and those who did not achieve reperfusion, as evident from serially obtained fibrinogen measurements (77 +/- 52 vs 84 +/- 24 mg/dl, difference not significant). Plasmin activity, measured serially from 15 minutes to 24 hours after urokinase in 7 patients, was maximal at 15 minutes and undetectable after 3 hours. Wall motion at the infarct site measured from contrast ventriculograms was significantly better at follow-up only in patients in whom reperfusion was achieved and who received urokinase within 2 hours after the onset of symptoms as compared with patients in whom reperfusion was not achieved (-1.2 +/- 1.4 vs -2.4 +/- 0.9 standard deviations from normal, p less than 0.05). Peak serum creatine kinase level was significantly lower in patients in whom reperfusion was achieved than in those in whom it was not or those who had rethrombosis (802 +/- 763 vs 1,973 +/- 1,071 U/liter, p less than 0.005).(ABSTRACT TRUNCATED AT 250 WORDS)

Dynamic mechanisms in human coronary stenosis

At the clinical level, coronary stenoses frequently behave as though the obstruction to flow were variable and not as rigidly fixed as previously imagined. Pressure (energy) lost in flow through a stenosis is the primary determinant of its hemodynamic impact. Ischemic episodes occur when pressure distal to the stenosis falls below that needed to perfuse the subendocardium. Three important properties of the stenosis contribute to variation in its pressure loss. First, loss is proportional to the square of stenosis flow. Thus proper distribution of perfusion is doubly vulnerable to conditions such as exercise, anemia, or pharmacologic vasodilation, which ordinarily increase myocardial blood flow. Second, pressure loss is proportional to the inverse fourth power of minimum lumen diameter. As a result, seemingly small changes in diameter are amplified to large changes in stenosis resistance. Third, a compliant arc of normal arterial wall borders part of the lumen in the majority of coronary lesions. This extremely important morphologic feature of stenoses permits transient variation in stenosis lumen diameter in response to drugs or to variation in endogenous vasomotor activity or intraluminal pressure. Although our understanding is incomplete, many of the clinical features of coronary disease and its pharmacologic responses are explained in terms of these stenosis properties and their interaction.

Diltiazem-induced blockade of sympathetically mediated constriction of normal and diseased coronary arteries: lack of epicardial coronary dilatory effect in humans

To determine mechanisms of benefit from diltiazem, 13 patients with coronary disease performed sustained isometric handgrip exercise and repeated the procedure during intravenous infusion of diltiazem (0.25 mg/kg bolus followed by 0.003 mg/kg/min). Cardiovascular responses to handgrip, diltiazem, their combination, and nitroglycerin were assessed by hemodynamic and electrocardiographic measurements and by computer-assisted measurements of normal and diseased segments of epicardial coronary arteries. Handgrip produced increases in heart rate (12%; p less than .001), pulmonary arterial pressure (19%; p less than .005), and pulmonary wedge pressure (33%; p less than .005). Diltiazem produced significant reductions in heart rate (7%; p less than .05) and aortic pressure (14%; p less than .001). Pulmonary arterial pressure and pulmonary wedge pressure were unchanged by diltiazem. Diltiazem did not prevent the increase in heart rate or in aortic or wedge pressure associated with handgrip. Diltiazem prolonged atrioventricular conduction from 0.18 +/- 0.03 to 0.20 +/- 0.03 sec (p less than .001). Compared with control values, nitroglycerin reduced aortic pressure (14%; p less than .005), pulmonary arterial pressure (38%; p less than .001), and pulmonary wedge pressure (42%; p less than .005). Heart rate was unchanged. The constriction (20%) in lumen area of normal coronary arterial segments during handgrip was effectively prevented by infusion of diltiazem (1%; p less than .001). Nitroglycerin produced a significantly greater increase (20%) in diameter of normal coronary arterial segments than diltiazem (3%; p less than .001) and tended to have a more favorable effect than diltiazem on stenosis minimum area and flow resistance.(ABSTRACT TRUNCATED AT 250 WORDS)

Reflex constriction of significant coronary stenosis as a mechanism contributing to ischemic left ventricular dysfunction during isometric exercise

To study the mechanisms of myocardial ischemia during isometric exercise, handgrip was sustained, for 4.5 min at 25% of maximum by 11 patients with at least one significant coronary stenosis each, during cardiac catheterization. After recovery, the handgrip that was repeated with simultaneous infusion of nitroglycerin (50 micrograms over 4 min) directly into the diseased vessel. The cardiovascular response was assessed by hemodynamic and by computer-assisted measurements of stenosis. During the first handgrip test pulmonary capillary wedge pressure rose 56% (15 to 23 mm Hg; p less than .001), the heart rate-systolic pressure product rose 33% (p less than .01), and the diseased epicardial arteries constricted. Luminal area in the stenotic segment was reduced by 35% (p less than .01), resulting in a 243% increase in estimated stenotic flow resistance (30 to 103 mm Hg/ml/sec; p less than .001). During handgrip with intracoronary nitroglycerin, the pressure-rate product again increased 33%, but relative to resting control, capillary wedge pressure fell 4 mm Hg in association with a 32% increase in luminal area of the stenosis and a 28% reduction in flow resistance (all significantly different from the response to handgrip alone: p less than .001, .01, and .005, respectively). Thus, coronary vasoconstriction, not increased pressure-rate product, is the dominant mechanism for ischemic left ventricular dysfunction during isometric exercise in patients with significant coronary stenoses.

A new digital electronic caliper for measurement of coronary arterial stenosis: comparison with visual estimates and computer-assisted measurements

Visual analysis of the severity of coronary stenosis is limited by observer variability. However, more complex techniques of proved accuracy are tedious and costly. Therefore, a new digital electronic caliper (DEC) was evaluated as a potentially more accurate, rapid and less costly alternative for measuring stenosis severity. Stenosis minimum diameter (Dmin) and percent diameter reduction (% S) were measured from the screen of the cine projector using a DEC. These measurements were compared with visual estimates (VIS) by 4 experienced angiographers and with measurements made by a computer-assisted method (QCA) of proved accuracy. In routine cineangiograms from 7 patients, 10 lesions were significant (greater than 50% S) and 8 were mild (less than 50% S). Variability, the standard deviation of multiple estimates of Dmin and % S, averaged 0.09 mm and 3.1% for QCA; 0.18 mm and 5.9% for DEC; and 0.26 mm and 7.4% for VIS. Compared with QCA, the visual determination of % S significantly underestimates (-5%; p less than 0.02) mild and overestimates (+11%; p less than 0.002) significant stenosis. VIS underestimates Dmin in significant lesions by 20% (p less than 0.04). In contrast, the mean error for DEC measurement of Dmin and % S was not significantly different from 0 in either lesion group. For the entire group of lesions, and particularly in significant lesions, the mean error for measurement of these 2 indexes of disease was significantly less with DEC than with VIS. Thus, variability and error with DEC are acceptably low for clinical use.(ABSTRACT TRUNCATED AT 250 WORDS)

Value of partial ejection fraction, volume increment, and regional wall motion in identifying patients with clinically significant coronary artery disease

Recent studies suggest that the partial ejection fraction (EF) in early systole is a more sensitive index of left ventricular (LV) dysfunction than the holosystolic EF. We examined LV volume, partial EF, and volume increment at each of 12 time points in systole to determine which parameter best distinguishes normal subjects from patients with coronary artery disease (CAD). Contrast ventriculograms, obtained either in the right anterior oblique projection (60 frames/sec) or in the biplane projection (30 frames/sec), of 58 normal subjects and 68 patients with CAD were studied. The endocardial contour in each frame of a sinus beat was traced to derive a volume curve. At each twelfth of systole, LV volume was extrapolated from the curve and the partial EF was calculated. The increment in volume between successive time points was also calculated. Both partial EF and LV volume in patients with CAD became progressively more abnormal with time; peak abnormality occurred at end-systole. In a subgroup of patients with CAD who had normal holosystolic EF, both partial EF and volume were normal throughout systole. The increment in volume with each twelfth of systole in patients with CAD deviated less than 1 SD from normal throughout systole. Thus, maximum abnormality in partial EF and volume occurs at end-systole. Of the parameters of global LV function tested, holosystolic EF best distinguishes patients with CAD from normal subjects. However, regional wall motion measured in the area of interest is more sensitive to localized abnormality, the severity of which may be overestimated or underestimated by the EF due to hyperkinesis or hypokinesis in other regions of the left ventricle.

Variability in the measurement of regional left ventricular wall motion from contrast angiograms

Four types of variability affecting quantification of regional wall motion from contrast left ventriculograms (LVgrams) were studied. These included beat-to-beat variability in 24 LVgrams, intraobserver and interobserver variability in 20 LVgrams, and study-to-study variability in serial LVgrams of 21 patients with stable coronary artery disease. Motion was measured at 100 equidistant chords perpendicular to a center line drawn midway between the end-diastolic and end-systolic contours and normalized for heart size. Variability was computed as the absolute difference between observations. Beat-to-beat, intraobserver, and interobserver variability at the 100 chords were similar, averaging 14%, 14%, and 17%, respectively, of the mean motion in 64 patients with normal ventriculograms. Study-to-study variability was significantly higher, averaging 30% of mean normal motion, but was reduced when regional motion was calculated as the mean motion of chords within a region of interest. Variability peaked at the apex. Realignment to correct for cardiac rotation significantly increased variability. Investigators whose methods of wall motion analysis rely on identification of the apex as a landmark should be aware of this source of potential variability and error.

Effect of interventions in salvaging left ventricular function in acute myocardial infarction: a study of intracoronary streptokinase

The ability of intracoronary streptokinase (STK) infused early in acute myocardial infarction (MI) to salvage left ventricular (LV) function was studied in 52 patients who underwent contrast angiography immediately after STK and 6 +/- 7 weeks later. Ten nonrevascularized patients had no lysis or reocclusion. Of 42 patients with thrombolysis, 22 with optimal reperfusion underwent coronary artery bypass grafting (CABG) to prevent rethrombosis (STK + CABG group) and 20 did not (STK group). Motion was measured at 100 chords around the left ventricle and expressed in standard deviations (SD) from the normal mean. Hypokinesia was computed as the mean motion of chords in the infarct artery territory and hyperkinesia on the opposite wall was similarly computed. Hypokinesia improved greater than or equal to 1 SD/chord in 9 STK + CABG patients (41%), 8 STK patients (30%) (p = not significant versus STK + CABG) and 0 nonrevascularized patients. However, the ejection fraction did not change because it was normal in acute MI despite severe hypokinesia due to hyperkinesia on the opposite wall, and a subsequent decrease in hyperkinesia masked significant improvement in hypokinesia. It is concluded that regional wall motion must be measured to adequately assess the effect of therapeutic interventions on LV function. Early thrombolysis in acute MI results in improved LV function. The main benefit of CABG is to prevent rethrombosis.

Prognostic and predictive value of exertional hypotension in suspected coronary heart disease

The prognostic and predictive value of exertional hypotension was assessed in 1,241 patients having treadmill maximal exercise testing, coronary arteriography, and follow-up averaging 5.4 years. Medically treated patients with coronary artery disease (CAD) with exertional hypotension had poorer survival than did those without such hypotension; however, maximum systolic pressure during exercise was a more powerful predictor of survival. Patients with exertional hypotension had more extensive CAD and more left ventricular (LV) dysfunction than did patients who had an increase in blood pressure with exertion; these findings probably account for the impaired survival. However, exertional hypotension, was an insensitive indicator of significant left main coronary artery stenosis, 3-vessel disease, or severe resting LV dysfunction.

Effect of coronary artery bypass grafting on subsequent hospitalization

The rates of hospitalization during follow-up for a matched pair cohort of medically and surgically treated patients from the Angiography Registry of Seattle Heart Watch were compared. Medically and surgically treated patients were matched according to extent of disease, left ventricular ejection fraction, age, and 3 other survival rate-related characteristics. There was a 26% reduction in cardiovascular hospitalizations in the surgically treated patients (19%/year) compared with the medically treated patients (26%/year). This was due to a significant reduction in hospitalization rate for myocardial infarction (surgically treated patients 1.1%/year, medically treated patients 2.6%/year), and for other cardiovascular reasons (surgically treated patients 12.5%/year, medically treated patients 15.7%/year). No significant (p = 0.146) reduction occurred in hospitalization rate for chest pain not due to myocardial infarction (surgically treated patients 5.6%/year, medically treated patients 7.7%/year). When the perioperative infarctions are included for the surgical cohort, the overall myocardial infarction rate is not significantly different (p = 0.173) between the 2 treatment groups (surgically treated patients 1.9%/year, medically treated patients 2.6%/year). Acute myocardial infarction was an uncommon reason for hospitalization, accounting for only 8% (55 of 685) of all cardiovascular hospitalizations, and was not related to the number of stenotic vessels in medically treated patients.

Quantitative contrast angiography for assessment of ventricular performance in heart disease

Contrast angiography provides much information about ventricular and valvular size and function. This review describes the calculation of left ventricular chamber volume and wall thickness and the derivation of ejection fraction, cardiac output, mass and wall tension and stress. In patients with valvular regurgitation, valve orifice area can be calculated by using the angiographic output and regurgitant flow determined by comparing the angiographic output with the cardiac output measured using Fick or indicator-dilution techniques. By analyzing ventricular volume in conjunction with pressure, it is possible to assess pressure-volume work, compliance and contractility. Regional wall motion can be measured from the change in ventricular contour with time. When applied clinically, these methods and measurements have been used to determine the hemodynamic characteristics of the compensated and decompensated left ventricle in valvular and coronary heart disease. The information derived from quantifying information in angiographic images contributes to patient diagnosis, assessment of prognosis and evaluation of therapy, and has added to our knowledge concerning the pathophysiology of heart disease.

Effect of perioperative myocardial infarction on late survival in patients undergoing coronary artery bypass surgery

From the Seattle Heart Watch angiography registry, the baseline characteristics and late survival of 77 patients who sustained operative infarction (new Q waves) with myocardial revascularization were compared with 1790 patients who underwent coronary artery bypass without perioperative infarction. With the exception of coronary collateral vessels, which were less frequently seen in the patients with perioperative infarction, no baseline or operative characteristic distinguished between the two groups. Late survival was clearly adversely affected by perioperative infarction. Five-year survival was 76% in patients with perioperative infarction, compared with 90% in those with no perioperative infarction.

Arteriographic assessment of coronary atherosclerosis. Review of current methods, their limitations, and clinical applications

Coronary arteriography is presently the definitive procedure for characterizing the location and severity of coronary atherosclerosis; and despite certain reported limitations, we believe that the properly performed coronary arteriogram provides a true picture of the arterial lumen in life. Yet this widely-used clinical tool is currently limited by imprecise and, to a certain extent, inappropriate subjective methods of interpretation. More objective methods for analysis of the arteriographic information content have been described. These include caliper- and vernier- based systems for measuring relative arterial narrowing, computer-assisted methods for making accurate measurements of absolute stenosis dimensions, and photodensitometric methods for extracting three-dimensional information from a planar image of the stenosis. The availability of these objective techniques has resulted in a considerable increase in our understanding of pathogenic mechanisms in coronary disease. Advances include an expanded understanding of the mechanisms of action of nitroglycerin and verapamil and of the coronary artery constriction induced by drugs of isometric stress. Stenosis measurements have served as the basis for evaluation of certain noninvasive techniques used to detect coronary disease. An analytical approach has been developed to characterize the progression (and regression) of coronary disease from serial arteriograms. We believe clinical investigations based on these techniques hold considerable promise for further advances in the understanding of human coronary pathophysiology.

Intravenous dipyridamole combined with isometric handgrip for near maximal acute increase in coronary flow in patients with coronary artery disease

Twenty-four patients with coronary artery disease were studied during cardiac catheterization to determine the effects of sustained isometric handgrip exercise and intravenous dipyridamole and their combination on coronary and systemic hemodynamics and measured coronary luminal caliber. During 4 to 5 minutes of 25 percent maximal handgrip, blood pressure and heart rate increased 24 and 19 percent, respectively, coronary sinus flow increased to 1.7 x baseline value, and epicardial coronary arteries constricted to increase predicted flow resistance by 40 percent in 36 diseased arterial segments. After a 4 minute intravenous infusion of dipyridamole (0.56 mg/kg body weight), systemic pressure decreased 8 percent, heart rate increased 23 percent, coronary sinus flow increased to 2.4 x baseline value and coronary luminal caliber was unchanged. During isometric handgrip initiated 6 minutes after the infusion of dipyridamole, systemic pressure and heart rate increased to 14 and 31 percent, respectively, above control values, coronary sinus flow increased to 3.3 x baseline value (3.8 x baseline value in patients with normal anterior perfusion) and stenotic flow resistance increased by 36 percent. The response of coronary flow to the combined stresses was 68 percent greater than the response to dipyridamole alone (p less than 0.02); these flow levels exceed values previously reported for the human coronary circulation. Aminophylline plus nitroglycerin appears to assure patient safety.

The mechanisms of nitroglycerin action: stenosis vasodilatation as a major component of the drug response

The effect of sublingual or intracoronary nitroglycerin (NTG) on luminal caliber in normal and diseased portions of epicardial coronary arteries was determined in 85 lesions from 57 typical patients with ischemic heart disease. Measurements were made from coronary angiograms, using a computer-assisted method and a carefully blinded protocol for analysis of the pre- and post- NTG angiograms. Luminal area in the "normal" portion of the diseased segment and at its maximum constriction and an estimate of flow resistance in the stenosis were computed. Luminal area increased 1.27 mm2 (p less than 0.001) in the "normal" regions, an average increase of 18% over the control area. Dilation with NTG depended strongly on vessel size; area increased 35% in normal vessels of 1.6-2.3 mm luminal diameter and only 9% in vessels 4.0-5.0 mm in diameter. Lesions were grouped into four levels of severity by percent stenosis. Minimum luminal area increased 0.35 mm2 (p less than 0.01) at the narrowest point in moderate lesions, a 22% area increase, and 0.14 mm2 (p less than 0.001) in severe lesions, a 36% area increase. Stenosis dilation resulted in an average 25% reduction (p less than 0.01) in estimated stenosis flow resistance in moderate lesions and a 38% reduction (p less than 0.001) in severe lesions. A statistically significant resistance reduction of greater than 20% occurred in 15 to 20 severe stenoses; only two of 20 showed no measurable dilation. We reviewed recent literature on hemodynamic responses to NTG and determined that changes of this magnitude are among the largest reported. We conclude that vasodilation of epicardial coronary stenosis is usually a major component of the beneficial response to NTG. We support that conclusion by demonstrating a striking improvement in ischemic left ventricular compliance abnormalities after low-dose intracoronary NTG.