Coronary vasodilator reserve is impaired in patients with hypertrophic cardiomyopathy and left ventricular dysfunction.

BACKGROUND: We tested the hypothesis that a reduced delivery of blood to the myocardium is involved in the development of systolic dysfunction of patients with hypertrophic cardiomyopathy (HCM). METHODS AND RESULTS: Eighty-four patients with HCM (62 men, age 43 +/- 12 years) were studied. Left ventricular dimensions and function (fractional shortening) were evaluated by 2-dimensional echocardiography. Myocardial blood flow (MBF) was measured by N13 -ammonia or O15 -water and positron emission tomography at baseline and after dipyridamole; coronary vasodilator reserve (CVR) was calculated as dipyridamole/baseline MBF. Patients with HCM in advanced New York Heart Association (NYHA) classes had lower dipyridamole MBF (NYHA class I = 1.57 +/- 0.64 vs class II = 1.52 +/- 0.58 vs class III = 0.96 +/- 0.32 mL/min per gram; analysis of variance, P <.05) and CVR (NYHA class I = 1.93 +/- 0.64 vs class II = 1.69 +/- 0.54 vs class III = 1.40 +/- 0.43; analysis of variance, P <.05). A positive linear correlation between fractional shortening and dipyridamole MBF was demonstrated (R = 0.23, P <.05), and patients with abnormal fractional shortening had lower dipyridamole MBF (1.07 +/- 0.43 vs 1.58 +/- 0.62 mL/min per gram, P <.01). CONCLUSIONS: Systolic dysfunction in HCM may be caused by a more severe alteration of the coronary vasodilator capacity.

Syncope and ventricular arrhythmias in hypertrophic cardiomyopathy are not related to the derangement of coronary microvascular function.

UNLABELLED: Non-sustained ventricular tachycardia on Holter and syncope have been considered risk factors for sudden death in hypertrophic cardiomyopathy. AIMS: In these patients the coronary vasodilator reserve is impaired despite normal coronaries, so we evaluated the correlation between the severity of coronary vasodilator reserve impairment and the occurrence of syncope and non-sustained ventricular tachycardia. METHODS AND RESULTS: Eighty-four patients with hypertrophic cardiomyopathy (62 males, age 43 +/- 12 years) had a two-dimensional echocardiographic study and a 48-h Holter. Myocardial blood flow was measured by positron emission tomography, at baseline and after dipyridamole, and the coronary vasodilator reserve was computed as dipyridamole myocardial blood flow/baseline myocardial blood flow. In 27 patients, subendocardial and subepicardial myocardial blood flow was measured in the septum and the subendocardial/subepicardial ratio was computed. Twenty of 84 patients had at least one syncopal episode, and 26 had at least one run of non-sustained ventricular tachycardia on Holter. Baseline and dipyridamole myocardial blood flow, coronary vasodilator reserve, and baseline and dipyridamole subendocardial/subepicardial myocardial blood flow ratio were similar in patients with and without syncope and with and without non-sustained ventricular tachycardia on Holter. However, patients with non-sustained ventricular tachycardia had larger left ventricular end-diastolic (47 +/- 6 vs 44 +/- 5 mm, P < 0.05) and end-systolic diameters (30 +/- 6 vs 27 +/- 4 mm, P < 0.05). CONCLUSIONS: (1) Coronary vasodilation is not more severely impaired in patients with hypertrophic cardiomyopathy and syncope or non-sustained ventricular tachycardia. (2) The left ventricle is more dilated in hypertrophic cardiomyopathy with non-sustained ventricular tachycardia.

Effect of verapamil on absolute myocardial blood flow in hypertrophic cardiomyopathy.

Angina, despite angiographically normal coronary arteries, is a common symptom in patients with hypertrophic cardiomyopathy (HC). Verapamil has been shown to ameliorate silent myocardial perfusion defects documented by thallium-201 in patients with HC. The aim of this study was to investigate the effects of verapamil on absolute regional myocardial blood flow and flow reserve, measured by positron emission tomography (PET) in patients with HC. Echocardiography, exercise stress testing, and measurements of myocardial blood flow at rest and after administration of intravenous dipyridamole (0.56 mg/kg) were undertaken in 20 patients with HC at baseline study and 8 +/- 2 weeks after double-blind randomization to either slow-release verapamil 240 mg or placebo once daily. During treatment, resting myocardial blood flow in the interventricular septum was 0.81 +/- 0.23 versus 0.96 +/- 0.42 ml/min/g in the placebo and verapamil group, respectively (p = NS between groups and when compared with respective baseline study); resting myocardial blood flow in the left ventricular free wall was 0.67 +/- 0.17 versus 0.74 +/- 0.45 ml/min/g, respectively (p = NS). After dipyridamole infusion, myocardial blood flow in the interventricular septum was 1.42 +/- 0.52 versus 1.92 +/- 1.23 ml/min/g (p = NS between groups and when compared with respective baseline study); myocardial blood flow in the left ventricular free wall was 1.25 +/- 0.41 versus 1.68 +/- 1.37 ml/min/g, respectively (p = NS).(ABSTRACT TRUNCATED AT 250 WORDS)

Adrenergically mediated coronary vasoconstriction in patients with syndrome X.

Several studies have shown that coronary vasodilator reserve is impaired in some patients with chest pain and angiographically normal coronary arteries. In a subgroup of these patients, who additionally show ST depression on the electrocardiogram during exercise and are generally labelled as having Syndrome X, the impairment of coronary flow reserve is associated with metabolic and functional signs consistent with an increased sympathetic drive. The aim of the present investigation was to ascertain whether the impairment of coronary vasodilator reserve in patients with Syndrome X is due to adrenergically mediated vasoconstriction of coronary microcirculation. Myocardial blood flow (MBF), at baseline and following intravenous infusion of dipyridamole (0.56 mg/kg over 4 minutes), was measured by means of 13N-ammonia and dynamic positron emission tomography in 10 females (mean age 52 +/- 8 years) with a chest pain history, ST-segment depression during exercise, and angiographically normal coronaries. The first MBF study was performed while the patients were off therapy; a repeat MBF study was performed following 1 week of treatment with the alpha-1 blocker doxazosin (2 mg/day). Off therapy MBF was 1.13 +/- 0.25 ml/min/g at baseline and increased to 2.35 +/- 0.66 ml/min/g following dipyridamole. Coronary vasodilator reserve (dipyridamole/baseline MBF) was 2.18 +/- 0.56. During treatment with doxazosin, baseline MBF was not different from the control value (1.25 +/- 0.50 ml/min/g), while added dipyridamole significantly increased MBF to 3.52 +/- 1.20 ml/min/g (p < 0.01 vs. off therapy). Coronary vasodilator reserve was significantly increased (2.91 +/- 0.92, p < 0.01 vs. control value) by doxazosin.(ABSTRACT TRUNCATED AT 250 WORDS)

Altered coronary vasodilator reserve and metabolism in myocardium subtended by normal arteries in patients with coronary artery disease.

OBJECTIVES: The aim of this study was to investigate coronary vasodilator reserve and metabolism in myocardium subtended by angiographically normal arteries remote from ischemia. BACKGROUND: After infarction, structural and functional changes occur in remote myocardium often subtended by normal arteries. Whether changes occur in regions remote from ischemic but noninfarcted myocardium is unknown. METHODS: Coronary vasodilator reserve was measured with positron emission tomography in 12 patients with single-vessel disease using intravenous dipyridamole (0.56 mg/kg for 4 min). In another 10 patients, simultaneous arterial/great cardiac vein catheterization was performed during atrial pacing to measure myocardial metabolism in regions subtended by diseased or normal arteries. RESULTS: Basal myocardial blood flow in stenosis-related regions was comparable to that in remote regions but was lower after dipyridamole administration (1.73 +/- 0.91 vs. 2.89 +/- 0.93 ml/min per g, p < 0.01), giving coronary vasodilator reserve values of 1.80 +/- 0.82 and 2.73 +/- 0.89 (p < 0.01). In normal control subjects, basal myocardial blood flow was 0.92 +/- 0.13 and 3.67 +/- 0.94 ml/min per g in the basal state and after dipyridamole (both p < 0.05 vs. values in remote regions), and coronary vasodilator reserve was 4.07 +/- 0.98 (p < 0.01) vs. values in remote regions). During pacing there was net lactate release in diseased regions (-18 +/- 27%, p < 0.05 vs. values in remote regions and control subjects) and extraction in remote regions (38 +/- 17%) and in normal control subjects (26 +/- 11%). Glucose and alanine extraction were increased in diseased (8 +/- 6% and 6 +/- 6%) and remote regions (6 +/- 3% and 4 +/- 3%), compared with values in normal control subjects (2 +/- 3% and -1 +/- 3%, both p < 0.05 vs. diseased and remote regions). CONCLUSIONS: Coronary vasodilator reserve is reduced and glucose and alanine metabolism is abnormal in regions subtended by normal arteries remote from ischemic but noninfarcted myocardium.

Evidence for a systemic defect of resistance-sized arterioles in hypertrophic cardiomyopathy.

BACKGROUND: To investigate whether the abnormalities of coronary arterioles observed in association with hypertrophic cardiomyopathy represent a generalized phenomenon, both forearm and coronary vasodilator reserve were measured in 12 patients with hypertrophic cardiomyopathy. METHODS: Forearm vasodilator reserve was evaluated by measuring minimal forearm vascular resistance (Rmin, the ratio of mean intra-arterial pressure to peak forearm blood flow measured by venous plethysmography) under conditions of maximal postocclusive reactive hyperemia. RESULTS: In a subgroup (n = 5) of patients, the intra-arterial infusion of sodium nitroprusside combined with arterial occlusion did not produce additional vasodilation, indicating that the ischemic stimulus was indeed maximal. Coronary reserve was quantitated by measuring left ventricular blood flow (13N-ammonia and positron emission tomography) and coronary resistance at baseline and after intravenous dipyridamole (0.56 mg/kg). Rmin was significantly greater in patients than in a group of age- and sex-matched controls. The percentage change in coronary resistance after dipyridamole was significantly related to Rmin, whereas no correlation was found between change in coronary resistance and individual septal thickness values. CONCLUSIONS: Independent of cardiac hypertrophy, systemic and coronary arterioles of patients with hypertrophic cardiomyopathy are affected by an abnormality that may contribute to the clinical evolution of this syndrome.

Coronary reserve and exercise ECG in patients with chest pain and normal coronary angiograms.

BACKGROUND: Coronary vasodilator reserve is reduced in some patients with a history of chest pain and angiographically normal coronary arteries. ECG changes suggestive of myocardial ischemia during exercise also can be demonstrated in a subset of these patients. METHODS AND RESULTS: We have investigated the correlation between coronary vasodilator reserve, assessed with 13N-labeled ammonia and positron emission tomography, and the ECG during exercise stress in 45 patients with a history of chest pain, angiographically normal coronary arteries, and a negative ergonovine test. ST segment depression on the ECG during exercise was present in 29 of 45 patients. Mean resting left ventricular blood flow was 1.04 +/- 0.22 ml.min-1.g-1; it increased to 1.32 +/- 0.47 ml.min-1.g-1 (p less than 0.01 versus baseline value) during atrial pacing and to 2.52 +/- 0.96 ml.min-1.g-1 (p less than 0.01 versus baseline value) after dipyridamole (0.56 mg/kg i.v.). No regional flow defects could be demonstrated in any patient during pacing or after dipyridamole. Myocardial flows after dipyridamole, however, did not show a normal frequency distribution (Kolmogorov-Smirnov test), and two patient populations could be identified. Twenty-nine (67%) patients had a mean left ventricular flow of 3.02 +/- 0.33 ml.min-1.g-1 after dipyridamole (range, 2.13-5.46 ml.min-1.g-1), and 14 (33%) patients had a mean flow of 1.48 +/- 0.29 ml.min-1.g-1 (range, 1.06-2.04 ml.min-1.g-1, p less than 0.01 versus the "high-flow group"). CONCLUSIONS: Approximately one third of patients in our series showed a reduced coronary vasodilator reserve. Although 12 of 14 patients in the "low-flow group" had ST segment depression during exercise stress, 16 of 29 patients in the high-flow group also had ST segment depression during exercise stress. Therefore, despite a good sensitivity (86%) in identifying patients with a blunted increment of coronary flow, the ECG response during exercise stress appears to have a rather low specificity (45%). This suggests that factors other than reduced coronary reserve and myocardial ischemia may play a role in the genesis of the ST segment depression in these patients.

[Psychological and social aspects in women with syndrome X]. / Aspetti psicologici e sociali nelle donne con sindrome X.

A sizeable proportion (20-30%) of patients undergoing coronary arteriography for a chest pain syndrome are found to have angiographically normal coronary arteries. Some of these subjects (10-15%) have ischemic-like electrocardiographic changes during stress and no evidence of spasm of the epicardial coronary arteries (syndrome X). The vast majority of these patients are middle aged females. In the present investigation we evaluated the psychological and social characteristics of a group of patients with syndrome X (PX, n = 30). The results obtained in the PX group were compared with those in a sex and age matched group of patients with angiographically proven coronary artery disease (PI, n = 32) and with those in a group of control subjects (C, n = 29). Two original questionnaires were employed to collect the demographic and family data. The psychological data were obtained through the following 4 questionnaires: Symptom Rating Test (SRT); Symptom Questionnaire (SQ); Illness Behaviour Questionnaire (IBQ); Maudsley Personality Inventory (MPI). The results of our study indicated that in most of the patients with syndrome X the psychological and social conditions are similar and they are not compatible with a satisfactory lifestyle. In most cases both family and social difficulties are present, which impose excessive workload and distress on the patients. Very often the beginning of the chest pain history tends to coincide with the periods of greatest stress and with the occurrence of dramatic events in the family. On the other hand, the onset of symptoms often has the effect of releasing some of the environmental pressure on the patient.(ABSTRACT TRUNCATED AT 250 WORDS)

Coronary vasodilation is impaired in both hypertrophied and nonhypertrophied myocardium of patients with hypertrophic cardiomyopathy: a study with nitrogen-13 ammonia and positron emission tomography.

To assess regional coronary reserve in hypertrophic cardiomyopathy, regional myocardial blood flow was measured in 23 patients with hypertrophic cardiomyopathy and 12 control subjects by means of nitrogen-13 ammonia and dynamic positron emission tomography. In patients with hypertrophic cardiomyopathy at baseline study, regional myocardial blood flow was 1.14 +/- 0.43 ml/min per g in the hypertrophied (20 +/- 3 mm) interventricular septum and 0.90 +/- 0.35 ml/min per g (p less than 0.05 versus septal flow) in the nonhypertrophied (10 +/- 2 mm) left ventricular free wall. These were not statistically different from the corresponding values in control subjects (1.04 +/- 0.25 and 0.91 +/- 0.21 ml/min per g, respectively, p = NS). After pharmacologically induced coronary vasodilation (dipyridamole, 0.56 mg/kg intravenously over 4 min), regional myocardial blood flow in patients with hypertrophic cardiomyopathy increased significantly less than in control subjects both in the septum (1.63 +/- 0.58 versus 2.99 +/- 1.06 ml/min per g, p less than 0.001) and in the free wall (1.47 +/- 0.58 versus 2.44 +/- 0.82 ml/min per g, p less than 0.001). In addition, patients with hypertrophic cardiomyopathy who had a history of chest pain had more pronounced impairment of coronary vasodilator reserve than did those without a history of chest pain. After dipyridamole, coronary resistance in the septum decreased by 38% in patients without a history of chest pain, but decreased by only 14% in those with such a history (p less than 0.05). Coronary resistance in the free wall decreased by 45% in patients without and by 27% in those with a history of chest pain (p = 0.06).(ABSTRACT TRUNCATED AT 250 WORDS)