Relation between exertional ischemia and prognosis in mildly symptomatic patients with single or double vessel coronary artery disease and left ventricular dysfunction at rest

The randomized multicenter trials indicate that survival in patients with coronary artery disease and left ventricular dysfunction is enhanced by surgical therapy compared with medical therapy. This beneficial effect of coronary bypass surgery was demonstrated in patients with either three vessel or left main coronary artery disease, but not in those with one or two vessel disease. To determine whether subgroups of mildly symptomatic patients with one or two vessel coronary artery disease and left ventricular dysfunction have an increased risk of death or cardiac events during medical therapy, 53 consecutive patients with angiographically defined one or two vessel disease and impaired left ventricular function (ejection fraction 20% to 40%) were studied by exercise electrocardiography (ECG) and rest and exercise radionuclide angiography. All but two patients had previous myocardial infarction, and all were asymptomatic or only mildly symptomatic during medical therapy. By univariate life table analysis, mortality during medical therapy was associated significantly with the ST segment response to exercise (p less than 0.05) and with both the exercise ejection fraction (p less than 0.05) and the magnitude of change in ejection fraction with exercise (p less than 0.005). In patients with an exercise ejection fraction greater than 30%, the probability of survival at 6 years was 97 +/- 3% (+/- SE) compared with a survival rate of 62 +/- 14% in the remaining subjects (p less than 0.005). Similarly, 6 year survival was 100% in patients whose ejection fraction increased from the value at rest but was only 74 +/- 10% in the remaining patients (p less than 0.005). Exercise capacity was not associated with survival.(ABSTRACT TRUNCATED AT 250 WORDS)

Beta-adrenergic stimulation with isoproterenol enhances left ventricular diastolic performance in hypertrophic cardiomyopathy despite potentiation of myocardial ischemia. Comparison to rapid atrial pacing

Impaired left ventricular relaxation and filling is an important pathophysiologic mechanism in hypertrophic cardiomyopathy. To determine whether isoproterenol, known to improve relaxation in isolated cardiac muscle, could favorably modify this effect, we assessed simultaneous left ventricular volume and regional systolic asynchrony (by radionuclide angiography), left ventricular pressure (by micromanometer catheters), and lactate metabolism in 12 patients with hypertrophic cardiomyopathy. Pressure-volume relations were studied during atrial pacing stress to induce myocardial ischemia and during isoproterenol infusion to similar heart rates. Angina occurred in 10 patients with pacing and in 11 patients during isoproterenol infusion; lactate consumption was reduced in nine patients during isoproterenol compared with pacing, including five patients who produced lactate with isoproterenol. During isoproterenol compared with pacing, peak left ventricular pressure was higher (205 +/- 33 vs. 142 +/- 21 mm Hg, p less than 0.001), ejection fraction was higher (77 +/- 10% vs. 71 +/- 12%, p less than 0.02), and regional systolic nonuniformity was diminished. Despite ischemia, these changes in load and nonuniformity during isoproterenol were associated with enhanced diastolic function compared with pacing tachycardia: isoproterenol reduced T 1/2, the half-time of pressure decline after peak negative dP/dt (from 46 +/- 10 to 33 +/- 6 msec, p less than 0.001), shifted the diastolic pressure-volume curve downward and rightward in 10 of 12 patients, and increased end-diastolic volume (from 77 +/- 18% to 100 +/- 11% of control values, p less than 0.001) with no change in end-diastolic pressure (19 +/- 7 to 19 +/- 5 mm Hg, p = NS). Thus, despite ischemia, isoproterenol improved left ventricular relaxation and filling compared with tachycardia in the absence of beta-adrenergic stimulation. Although isoproterenol is detrimental in hypertrophic cardiomyopathy by provoking ischemia, these data suggest that the adverse effects of ischemia on ventricular relaxation and distensibility may be alleviated by beta-adrenergic stimulation, possibly as a result of enhanced inactivation and restored load sensitivity.

Cardiorespiratory effects of immunotherapy with interleukin-2

The administration of interleukin 2 (IL-2) and lymphokine-activated killer (LAK) cells can mediate the regression of cancer. Treatment with IL-2 is associated with significant cardiorespiratory effects, as well as a leaky capillary syndrome requiring careful fluid management. A mild reversible depression of cardiac function is also associated with IL-2 treatment. All patients treated with recombinant IL-2 alone, with transfer of LAK cells, or with cyclophosphamide between December 1984 and September 1987 (total of 423 treatment courses in 317 total patients) were evaluated as to the development of significant cardiorespiratory toxicity. Of the 423 treatment courses, only 1.8% were associated with severe peripheral edema and only 2.8% and 3.1% respectively, were associated with significant ascites or pleural effusions. Thirty-nine of 423 patients (9.2%) had severe respiratory distress and 27 patients required intubation (6.4%). Cardiovascular effects included tachycardia and hypotension requiring vasopressor administration in 65% and intravenous (IV) fluid administration. Weight gain greater than or equal to 10% of body weight was noted in 32% of the 423 patients. Arrhythmias were primarily supraventricular (9.7%) and responded well to conventional medical treatments. Angina or ischemic changes were noted in 2.6% of patients and myocardial infarction in 1.2%. IL-2 caused peripheral vasodilation, with a significant decrease in peripheral vascular resistance (2,254 +/- 398 v 1,303 +/- 351 dyne.s.cm-5, P less than .0001), and an increase in heart rate (66.2 +/- 10 v 104.3 +/- 9.6 beats/min, P less than .0001). There was also evidence of mild cardiac dysfunction, with a significant decrease in the left ventricular stroke work (LVSW) index (P less than .0001) and ejection fraction (LVEF) (from 58% +/- 10% to 52% +/- 9%, P less than .03). A repeat LVEF performed after 1 to 3 months, had returned to baseline values (60% +/- 10%). A mean 64% increase in the rate of disappearance of radioactive iodine (125I) albumin (P less than .05) consistent with the development of a leaky capillary syndrome was noted. Patients with underlying cardiorespiratory diseases may be at greater risk during IL-2 administration and should not be selected to undergo this treatment.

Effect of electrical stimulus parameters on the development and propagation of action potentials in short excitable fibres

Intracellular action potentials (IAPs) produced by short fibres in response to their electrical stimulation were analysed. IAPs were calculated on the basis of the Hodgkin-Huxley (1952) model by the method described by Joyner et al. (1978). Principal differences were found in processes of activation of short (semilength L less than 5 lambda) and long fibres under near-threshold stimulation. The shorter the fibre, the lower was the threshold value (Ithr). Dependence of the latency on the stimulus strength (Ist) was substantially non-linear and was affected by the fibre length. Both fibre length and stimulus strength influenced the IAP amplitude, the instantaneous propagation velocity (IPV) and the site of the first origin of the IAP (and, consequently, excitability of the short fibre membrane). With L less than or equal to 2 lambda and Ithr less than or equal to Ist less than or equal to 1.1Ithr, IPV could reach either very high values (so that all the fibre membrane fired practically simultaneously) or even negative values. The latter corresponded to the first origin of the propagated IAP, not at the site of stimulation but at the fibre termination or at a midpoint. The characters of all the above dependencies were unchanged irrespective of the manner of approaching threshold (variation of stimulus duration or its strength). Reasons for differences in processes of activation of short and long fibres are discussed in terms of electrical load and latency. Applications of the results to explain an increased jitter, velocity recovery function and velocity-diameter relationship are also discussed.

Angina due to coronary microvascular disease in hypertensive patients without left ventricular hypertrophy

When angina occurs in patients with hypertension, it is usually attributed to coronary artery disease or left ventricular hypertrophy. To determine the contribution of coronary microvascular abnormalities to angina in patients with hypertension, we evaluated hypertensive patients without coronary artery disease or left ventricular hypertrophy by measuring the coronary responses to rapid atrial pacing before and after administration of ergonovine. We compared 12 hypertensive patients who had pacing-induced angina with 13 normotensive subjects without such angina. The two groups had similar coronary flow (in the great cardiac vein) at rest; however, pacing increased coronary flow less in hypertensive patients with angina than in normotensive subjects (48 vs. 83 percent; P = 0.05). In the hypertensive patients with angina, pacing after ergonovine increased coronary flow by only 32 percent (as compared with 48 percent before ergonovine; P less than 0.05) and decreased coronary resistance by 15 percent (as compared with 28 percent before ergonovine; P less than 0.05), indicating the presence of ergonovine-induced vasoconstriction. In normotensive subjects, in contrast, cardiac pacing after ergonovine increased coronary flow by 112 percent (P less than 0.001), and its effect on coronary resistance was not different from that of pacing before ergonovine. The hypertensive patients with angina had a significant increase in myocardial oxygen extraction during pacing after ergonovine and less of an increase in myocardial lactate consumption - a response consistent with the presence of myocardial ischemia. Thus, angina in hypertensive patients without epicardial coronary disease may be caused by myocardial ischemia, which appears to be due to an abnormally elevated resistance of the coronary microvasculature.

Long-term serial changes in left ventricular function and reversal of ventricular dilatation after valve replacement for chronic aortic regurgitation

In most patients with aortic regurgitation, valve replacement results in reduction in left ventricular dilatation and an increase in ejection fraction. To determine the relation between serial changes in ventricular dilatation and changes in ejection fraction, we studied 61 patients with chronic severe aortic regurgitation by echocardiography and radionuclide angiography before, 6-8 months after, and 3-7 years after aortic valve replacement. Between preoperative and early postoperative studies, left ventricular end-diastolic dimension decreased (from 75 +/- 6 to 56 +/- 9 mm, p less than 0.001), peak systolic wall stress decreased (from 247 +/- 50 to 163 +/- 42 dynes x 10(3)/cm2), and ejection fraction increased (from 43 +/- 9% to 51 +/- 16%, p less than 0.001). Between early and late postoperative studies, diastolic dimension and peak systolic wall stress did not change, but ejection fraction increased further (to 56 +/- 19%, p less than 0.001). The increase in ejection fraction correlated with magnitude of reduction in diastolic dimension between preoperative and early postoperative studies (r = 0.63), between early and late postoperative studies (r = 0.54), and between preoperative and late postoperative studies (r = 0.69). Late increases in ejection fraction usually represented the continuation of an initial increase occurring early after operation. Thus, short-term and long-term improvement in left ventricular systolic function after operation is related significantly to the early reduction in left ventricular dilatation arising from correction of left ventricular volume overload. Moreover, late improvement in ejection fraction occurs commonly in patients with an early increase in ejection fraction after valve replacement but is unlikely to occur in patients with no change in ejection fraction during the first 6 months after operation.

The effect of coronary artery bypass grafting on left ventricular systolic function at rest: evidence for preoperative subclinical myocardial ischemia

Successful coronary artery bypass grafting (CABG) improves exercise-induced left ventricular (LV) dysfunction in patients with coronary artery disease (CAD), but its potential for improving resting LV function remains controversial. To assess the influence of CABG on LV function at rest, 31 CAD patients without previous myocardial infarction were studied before and 6 months after CABG by radionuclide angiography after all cardiac medicines were withdrawn. No patient had angina or ischemic electrocardiographic changes at rest. In 27 patients with patent bypass grafts, CABG significantly increased LV ejection fraction during exercise (47 +/- 11% before to 63 +/- 9% after operation, p less than 0.001), indicating reduction in exercise-induced LV ischemia. Moreover, LV ejection fraction at rest also increased (55 +/- 9 to 60 +/- 8%, p less than 0.001), with 20 of 27 patients manifesting an increase compared with preoperative values. Eleven of these 20 patients had apparently normal LV function at rest (ejection fraction and regional wall motion) before CABG. LV regional ejection fraction was computed by dividing the LV region of interest into 20 sectors. Regional analysis indicated that improved ejection fraction at rest after CABG occurred in regions developing ischemia during exercise before CABG. In 4 patients with occluded grafts, the ejection fraction at rest was unchanged by CABG globally (59 +/- 8 to 58 +/- 9%, difference not significant) and regionally. Thus, LV global and regional function at rest improved after successful CABG, even in patients with normal global LV ejection fraction and no visually detectable wall motion abnormality before surgery.(ABSTRACT TRUNCATED AT 250 WORDS)

Relation between serum nifedipine concentration and hemodynamic effects in nonobstructive hypertrophic cardiomyopathy

The relation between nifedipine concentration and hemodynamic effects after sublingual administration of 10 or 20 mg was examined in 13 patients with nonobstructive hypertrophic cardiomyopathy (HC). Serum nifedipine concentrations were determined by gas chromatography and were not related to dose. Peripheral vascular resistance decreased as a function of nifedipine concentration (r = -0.63, p less than 0.001); this was associated with a concentration-related increase in heart rate (r = 0.56, p less than 0.001) and in cardiac index (r = 0.50, p less than 0.001). However, evidence for a pure vasodilator effect of nifedipine was inconsistent, in that the change in stroke volume index with nifedipine was not significant. Although stroke volume index increased at nifedipine concentrations between 60 and 120 ng/ml (38 +/- 6 to 42 +/- 4 ml/m2, p less than 0.01), it decreased at concentrations greater than 120 ng/ml (40 +/- 3 to 38 +/- 4 ml/m2, p less than 0.01). Moreover, pulmonary artery wedge pressure increased at nifedipine concentrations greater than 120 ng/ml (11 +/- 2 to 16 +/- 4 mm Hg, p less than 0.001), suggesting either depressed left ventricular (LV) systolic function or reduced LV filling. To investigate these possible mechanisms, LV systolic and diastolic function was studied during catheterization with a nonimaging scintillation probe in 6 of the 13 patients. In these subjects, heart rate was held constant by atrial pacing.(ABSTRACT TRUNCATED AT 250 WORDS)

The effect of energy window on cardiac ejection fraction

ECG gated gamma-ray energy spectra from the left ventricle were created each 50 msec during the cardiac cycle. Nine of ten subjects were studied with a nonimaging Nal probe, and the tenth with a high-resolution Germanium detector. Placing multiple energy windows over the energy spectra, EF was found to vary with the energy window selected. Moving a 20% window across the photopeak produced a roughly linear increase in EF with energy (2.3 EF units per 10 keV increase in energy) in eight of the ten subjects. Dividing the photopeak into a low (126-140 keV) and high-energy (140-154 keV) portion gave significantly different EFs (high energy exceeding low energy by 17%). Increasing the width of a narrow window centered about the photopeak produced negligible change in EF. Examining the energy spectra showed that the small-angle scattered radiation (126-139 keV) was proportionately greater at end systole than at end diastole, after normalizing the spectra to the same photopeak area.

Effects of aging on asynchronous left ventricular regional function and global ventricular filling in normal human subjects

In many patients with coronary artery disease or hypertrophic cardiomyopathy, reduced left ventricular rapid diastolic filling is related to asynchronous left ventricular regional diastolic function. Because left ventricular filling also declines with aging in normal subjects, in this study the influence of regional ventricular diastolic asynchrony on global ventricular filling as a function of age was investigated in 66 normal volunteers aged 19 to 77 years (mean 42) by radionuclide angiography. No subject had systemic hypertension or left ventricular hypertrophy. Indexes of left ventricular systolic function at rest did not vary with age, but rapid diastolic filling significantly declined with age: peak filling rate decreased (r = 0.69), time to peak filling rate increased (r = 0.53) and magnitude of rapid filling (% of left ventricular end-diastolic volume) decreased (r = 0.76) with aging. Left ventricular synchrony was assessed from regional volume curves derived by dividing the global ventricular region of interest into four quadrants. Indexes of systolic synchrony were unaffected by age, but regional variation in time to peak filling rate, an index of diastolic asynchrony, increased with aging (r = 0.51, p less than 0.001). Moreover, variation in time to peak filling rate correlated with global peak filling rate and magnitude of rapid filling (r = 0.48 and 0.54, p less than 0.001 for both). Multivariate analysis indicated that these effects were independent of age-related changes in blood pressure. Thus, aging alters left ventricular diastolic function, with reduced rate and extent of the rapid filling phase related to increased regional diastolic asynchrony.(ABSTRACT TRUNCATED AT 250 WORDS)

Myocardial perfusion abnormalities in patients with hypertrophic cardiomyopathy: assessment with thallium-201 emission computed tomography

Myocardial ischemia may play a critical role in the symptomatic presentation and natural history of hypertrophic cardiomyopathy (HCM). To assess the relative prevalence and functional significance of myocardial perfusion abnormalities in patients comprising the broad clinical spectrum of HCM, we studied 72 patients (ages 12 to 69 years, mean 40) using thallium-201 emission computed tomography. Imaging was performed immediately after maximal exercise and again after a 3 hr delay. Regional perfusion defects were identified in 41 of the 72 patients (57%). Fixed or only partially reversible defects were evident in 17 patients, 14 of whom (82%) had left ventricular ejection fractions of less than 50% at rest. Twenty-four patients demonstrated perfusion defects during exercise that completely reversed at rest; all had normal or hyperdynamic left ventricular systolic function (ejection fraction greater than or equal to 50%). Perfusion abnormalities were present in all regions of the left ventricle. However, the fixed defects were observed predominantly in segments of the left ventricular wall that were of normal or only mildly increased (15 to 20 mm) thickness; in contrast, a substantial proportion (41%) of the completely reversible defects occurred in areas of moderate-to-marked wall thickness (greater than or equal to 20 mm, p less than .001). Neither a history of chest pain nor its provocation with treadmill exercise was predictive of an abnormal thallium study, since regional perfusion defects were present in 10 of 18 (56%) completely asymptomatic patients, compared with 31 of 54 (58%) symptomatic patients. These data indicate that myocardial perfusion abnormalities occur commonly among patients with HCM. Fixed or only partially reversible defects suggestive of myocardial scar and/or severe ischemia occur primarily in patients with impaired systolic performance. Completely reversible perfusion abnormalities occur predominantly in patients with normal or supranormal left ventricular systolic function. Such dynamic changes in regional thallium activity may reflect an ischemic process that contributes importantly to the clinical manifestations and natural history of HCM.

Prognostic implications of symptomatic versus asymptomatic (silent) myocardial ischemia induced by exercise in mildly symptomatic and in asymptomatic patients with angiographically documented coronary artery disease

Patients with coronary artery disease (CAD) may undergo periods of reversible myocardial ischemia without experiencing angina. To study the prognostic implications of "silent" myocardial ischemia induced by exercise, exercise electrocardiography and radionuclide angiography were performed in 131 consecutive patients with CAD, preserved left ventricular (LV) function at rest and mild or no symptoms during medical therapy. All patients who died during medical therapy were in the subgroup of patients with 3-vessel CAD in whom exercise-induced ischemia developed, which was characterized by both a decrease in LV ejection fraction and ST-segment depression. Patients in whom angina pectoris developed during exercise (54% of all patients) had a greater prevalence of this combined ischemic response to exercise than patients without angina (61% vs 27%, p less than 0.001) and also a greater prevalence of left main or 3-vessel CAD (59% vs 25%, p less than 0.001). However, when inducible ischemia was demonstrated, risk stratification and prognosis were the same whether the ischemic episode was symptomatic or silent. Among patients having both a reduction in ejection fraction and a positive ST-segment response, the likelihood of significant left main narrowing (13% vs 26%), 3-vessel CAD (56% vs 51%) and death during subsequent medical therapy (16% vs 9%) was similar in patients with silent compared to those with symptomatic ischemia. These data indicate that patients in whom angina develops during exercise have a greater prevalence of high-risk coronary anatomy and of inducible ischemia than patients without angina. However, once inducible ischemia is documented, the symptomatic response to exercise appears irrelevant for prognostic or risk stratification considerations.

Noninvasive assessment of left ventricular diastolic function by pulsed Doppler echocardiography in patients with hypertrophic cardiomyopathy

Hypertrophic cardiomyopathy is a primary myocardial disease in which symptoms may frequently result from impaired left ventricular relaxation, filling and compliance. In the present investigation, Doppler echocardiography was utilized to measure transmitral flow velocity and thereby assess left ventricular diastolic performance noninvasively in a group of 111 patients representative of the broad clinical spectrum of hypertrophic cardiomyopathy. In patients with hypertrophic cardiomyopathy, all Doppler indexes of diastolic relaxation and filling differed significantly (p less than 0.001) from those obtained in 86 control subjects without heart disease, namely, prolongation of isovolumic relaxation (94 +/- 24 versus 78 +/- 12 ms) and of the early diastolic peak of flow velocity (244 +/- 55 versus 220 +/- 28 ms), as well as slower deceleration (3.4 +/- 1.4 versus 4.9 +/- 1.3 m/s2) and reduced maximal flow velocity in early diastole (0.5 +/- 0.2 versus 0.6 +/- 0.1 m/s). As an apparent compensation for impaired relaxation and early diastolic filling, the atrial contribution to left ventricular filling was increased, as shown by increased late diastolic flow velocity (0.4 +/- 0.3 versus 0.3 +/- 0.1 m/s) and reduced ratio of maximal flow velocity in early diastole to that in late diastole (1.4 +/- 0.8 versus 2.1 +/- 0.9). The vast majority of patients with hypertrophic cardiomyopathy (91 [82%] of 111) showed evidence of impaired left ventricular diastolic performance, as assessed from the Doppler waveform. Abnormal Doppler diastolic indexes were identified with similar frequency in patients with (78%) or without (83%) left ventricular outflow obstruction, as well as in patients with (84%) or without (80%) cardiac symptoms. However, patients with nonobstructive hypertrophic cardiomyopathy showed more severe alterations in the Doppler indexes of diastolic function than did patients with obstruction. Thus, abnormal diastolic performance as assessed by Doppler echocardiography was apparent in the vast majority of the study patients with hypertrophic cardiomyopathy, independent of the presence or absence of cardiac symptoms or a subaortic pressure gradient. The high frequency with which diastolic abnormalities are identified in asymptomatic patients with hypertrophic cardiomyopathy suggests that impaired diastolic performance may be present at a time in the natural history of the disease when functional limitation is not yet evident.

Occurrence and significance of progressive left ventricular wall thinning and relative cavity dilatation in hypertrophic cardiomyopathy

This investigation was undertaken to assess the prevalence of systolic dysfunction, left ventricular (LV) wall thinning and cavity enlargement in a large population of patients with hypertrophic cardiomyopathy (HC), and to determine the role of these conditions in the natural history of this disease. Of 217 consecutively studied patients with HC, most of whom were severely symptomatic, 197 (91%) had an LV ejection fraction of 50% or more and 20 (9%) had an ejection fraction of less than 50% as assessed with radionuclide angiography. Changes in LV wall thickness and cavity dimension were evaluated using serial M-mode and 2-dimensional echocardiography over an average follow-up of 3.6 years in 67 of the 217 patients (54 with ejection fraction of greater than or equal to 50% and 13 with ejection fraction less than 50%). A substantial decrease (at least 5 mm) in LV wall thickness was seen in 8 of the 13 patients (62%) with an ejection fraction greater than or equal to 50%, but in only 2 of the 54 patients (4%) with an ejection fraction greater than or equal to 50% (p less than 0.001). LV cavity dimension increased significantly over the period of follow-up in the 13 patients with depressed ejection fraction (from 44 +/- 5 to 49 +/- 7 mm, p less than 0.005); however, absolute cavity size remained normal (less than or equal to 52 mm or less) in 10 of these 13 patients.(ABSTRACT TRUNCATED AT 250 WORDS)

Significance of abnormal blood pressure response during exercise-induced myocardial dysfunction after recent acute myocardial infarction

The relation between exercise left ventricular ejection fraction and blood pressure (BP) responses after an acute myocardial infarction (AMI) was investigated. Twenty-eight to 37 days after an uncomplicated AMI, 224 consecutive patients underwent exercise radionuclide angiography in the 40 degrees semisupine position. In 180 patients (group A, 80%), BP increased more than 5 mm Hg every stage; in 44 patients, BP responses were abnormal; in 33 (group B, 15%), BP did not increase during 2 stages; in 11 (group C, 5%), it decreased more than 5 mm Hg after an initial increase. Ejection fraction did not differ significantly among the 3 groups at rest (51 +/- 13 in group A, 50 +/- 18 in group B, 47 +/- 13 in group C [difference not significant]) or at peak exercise (51 +/- 16% in group A, 46 +/- 19% in group B, and 43 +/- 16% in group C, [difference not significant]). Exercise-induced left ventricular failure or hemodynamic decompensation occurred in 22 patients. In these patients, ejection fraction at rest was 44 +/- 19% and decreased to 35 +/- 16% (p less than 0.05) with exercise. Only 9 of these patients (41%) had abnormal BP responses, with the other 13 (59%) showing a normal BP responses. The The 35 patients with abnormal BP responses in the absence of hemodynamic decompensation were asymptomatic, terminating exercise because of fatigue. The ejection fraction at rest and during exercise in these patients was similar to that in patients with normal BP responses.(ABSTRACT TRUNCATED AT 250 WORDS)

Regional left ventricular asynchrony and impaired global left ventricular filling in hypertrophic cardiomyopathy: effect of verapamil

Left ventricular relaxation and filling are impaired in many patients with hypertrophic cardiomyopathy. To investigate the influence of regional heterogeneity on these global abnormalities, 48 patients with hypertrophic cardiomyopathy and sinus rhythm were studied by radionuclide angiography before and after 1 to 2 weeks of verapamil therapy (320 to 640 mg/day, median 480). Left ventricular regional function was assessed by subdividing the ventricular region of interest into 20 sectors and into four quadrants from which regional time-activity curves were derived. Diastolic asynchrony was measured as the regional variation in timing between minimal volume and peak filling rate, and heterogeneity in the magnitude of rapid diastolic filling was measured as the regional variation in percent contribution of atrial systole to end-diastolic volume. Compared with 28 normal subjects, the patients with hypertrophic cardiomyopathy had greater regional variation in both timing (35 +/- 24 versus 12 +/- 6 ms, p less than 0.001) and magnitude (10 +/- 6 versus 7 +/- 4%, p less than 0.02) of rapid filling. Verapamil reduced the regional variation in timing (to 21 +/- 16 ms, p less than 0.001) and magnitude (to 7 +/- 3%, p less than 0.001) of rapid filling. These regional changes, indicating more uniform regional diastolic performance after verapamil, were associated with improved global diastolic filling: global rapid filling increased in both rate and magnitude and time to peak filling rate decreased. These findings indicate that the beneficial effect of verapamil on left ventricular diastolic function in hypertrophic cardiomyopathy may be mediated by reduction in regional asynchrony.

Determinants of ventricular arrhythmias in mildly symptomatic patients with coronary artery disease and influence of inducible left ventricular dysfunction on arrhythmia frequency

To determine the relation among ventricular arrhythmias, prognostic factors and reversible ischemia in coronary artery disease, 131 drug-free, minimally symptomatic patients were studied by radionuclide angiography and 24 hour Holter electrocardiographic monitoring. High grade ventricular arrhythmias (couplets, salvos of premature ventricular complexes and R on T phenomenon) were observed in 33 patients (25%) and were related to lower rest and exercise ejection fraction, greater number of stenotic coronary arteries and higher prevalence of regional wall motion abnormalities at rest (all p less than or equal to 0.1). Among patients with subnormal rest ejection fraction, high grade arrhythmias occurred with greater prevalence in those with reversible left ventricular dysfunction (reduction in ejection fraction) during exercise compared with those with a normal ejection fraction response (59 versus 23%, p less than 0.05), a relation observed principally in patients with multivessel disease. These data indicate that in minimally symptomatic patients with coronary artery disease, arrhythmias are related to both extent of disease and severity of regional and global ventricular dysfunction and are most prevalent in patients with ventricular dysfunction and evidence of inducible ischemia, factors indicating poor long-term prognosis during medical therapy.