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Biomedical subjects

C H McCabe

Publications and source records attributed to C H McCabe.

At least 91 records · Page 5Linked to original sources
PubMed1985

Value of arm exercise testing in detecting coronary artery disease.

Alternative methods of exercise testing are needed for patients with vascular, orthopedic or neurologic conditions who cannot perform leg exercise. To determine the sensitivity of arm exercise in detecting coronary artery disease (CAD), 30 patients with angina pectoris performed both arm ergometry and treadmill testing before coronary angiography. All patients had at least 70% diameter reduction in 1 or more major coronary arteries. Ischemic ST depression (greater than or equal to 1 mm) or angina occurred more frequently (86%, 26 patients) with leg exercise than with arm exercise (40%, 12 patients). There was no significant difference in peak rate-pressure product achieved with either test, although the peak oxygen consumption was greater during leg exercise than during arm exercise (18 vs 13 ml/kg/min, respectively, p less than 0.001). For concordantly positive tests, the oxygen consumption at onset of ischemia was significantly lower during arm testing than during leg testing (12 vs 17 ml/kg/min, respectively, p less than 0.001). There was no significant difference in heart rate during either test at onset ischemia. Thus, arm exercise testing is a reasonable, but not equivalent, alternative to leg exercise testing in patients who cannot perform leg exercise.

Aged↗
PubMed1985

Determinants of operative mortality and long-term survival in patients with unstable angina. The CASS experience.

To identify the factors that determine operative mortality and long-term survival, we analyzed the data from 3,311 patients who underwent surgical therapy for unstable angina according to clinical presentation. Overall operative mortality was 3.9% and no differences in operative mortality were found between patients with coronary insufficiency, new-onset angina, rest angina, or changing patterns of angina. Logistic regression analysis indicated that age, left ventricular score, and presence of a left main stenosis in a left dominant circulation were related to operative mortality. The 7 year cumulative survival rate was 79%. Features predictive of long-term outcome by Cox analysis included left ventricular score, congestive heart failure score, other illness, extent of coronary disease, and cardiomegaly. Operative mortality of those patients who underwent coronary bypass during their initial hospitalization with unstable angina was similar to that of patients who were discharged and readmitted for operation at a later date. Thus, patients with unstable angina demonstrate a relatively low operative mortality, which is unrelated to the clinical presentation. Long-term survival is primarily determined by clinical and angiographic markers of left ventricular dysfunction, associated illness, and the extent of coronary disease.

Angina Pectoris↗
PubMed1985

Exercise testing in the Coronary Artery Surgery Study randomized population.

Exercise electrocardiographic stress testing was performed in 81% of the 780 patients randomized in the Coronary Artery Surgery Study at entry. The cumulative survival at the end of 7 year follow-up was 90% for those assigned to surgical treatment and 88% for those assigned to medical therapy (p = NS). These survival rates did not differ significantly from either those of the entire randomized cohort or those of the 149 patients who did not have a qualifying exercise test at baseline. No differences in important baseline characteristics existed between those who were exercised and not exercised at entry. Stratification of patients according to the degree of ST segment depression (less than 1 mm, greater than or equal to 1 mm, greater than 2 mm) and final exercise stage achieved during a Bruce protocol treadmill test (final stage less than or equal to 1, stage 2 and greater than or equal to stage 3) failed to show any significant differences in 7 year survival rates between medically and surgically assigned patients. Additionally no differences in survival were noted within either the medical or surgical groups regardless of the degree of ST segment depression or the final stage achieved. The presence of exercise-induced angina, however, identified patients who had a survival advantage if assigned to surgical therapy, with a 7 year survival rate of 94% compared with 87% for medically assigned patients (p = .007).(ABSTRACT TRUNCATED AT 250 WORDS)

Adult↗
PubMed1984

Role of percutaneous transluminal coronary angioplasty in the treatment of unstable angina. Report from the National Heart, Lung, and Blood Institute Percutaneous Transluminal Coronary Angioplasty and Coronary Artery Surgery Study Registries.

The acute and long-term consequences of PTCA performed in patients with unstable angina was determined in 442 patients with 1-vessel CAD who were enrolled in the NHLBI PTCA Registry. These patients were compared with 214 similar patients in the PTCA Registry with stable angina and with 330 patients with unstable angina from the NHLBI CASS Registry who underwent CABG. The 3 groups had similar baseline characteristics. The immediate angiographic success after PTCA was not different between patients with stable and those with unstable angina. The in-hospital mortality rate was 0.9% for the PTCA group with unstable angina and 0.47% for the PTCA group with stable angina. The combined 18-month mortality and MI rate was low in both groups (10.8 and 9.5%, respectively). No differences were observed in the mortality and MI rates between patients with unstable angina treated surgically or with PTCA. Both revascularization procedures markedly reduced symptoms of angina. Ninety-two percent of the PTCA group reported improvement in their angina, whereas 80% of the surgical group had a reduction in angina (p less than 0.05). The results from this observational study suggest that PTCA can be performed as safely and successfully in patients with unstable angina as in those with stable angina. PTCA compares favorably with CABG in patients with unstable angina in that the procedure is associated with low mortality and morbidity rates, while marked improvement in symptoms can be expected. Thus, PTCA could be considered an alternative to CABG in patients with unstable angina who have the appropriate anatomic characteristics.

Angina Pectoris↗
PubMed1984

The efficacy and safety of high-dose verapamil and diltiazem in the long-term treatment of stable exertional angina.

The efficacy and safety of high-dose verapamil (480 mg/day) and diltiazem therapy (360 mg/day) were compared in separate cohorts of 26 and 20 patients, respectively. All patients had stable exertional angina and underwent an initial 6-week double-blind, placebo-controlled, randomized phase followed by a 12-month open-label period. Angina attacks were reduced by verapamil (6.3 +/- 7.5 to 2.5 +/- 4.1 attacks per week, p less than 0.001) and by diltiazem (9.2 +/- 7.5 to 3.0 +/- 3.1 attacks per week, p less than 0.001), while treadmill time increased with both verapamil (372 +/- 132 to 444 +/- 108 s, p less than 0.001) and diltiazem (412 +/- 175 to 536 +/- 164 s, p less than 0.001) during the short-term study. Both agents continued to show similar salutory effects at the end of one year. The beneficial effects of both drugs appeared to be related in part to a reduction of the rate-pressure product during submaximal exercise (12% by verapamil, 7% by diltiazem, both p less than 0.05). Adverse effects were few and consisted primarily of mild constipation in six patients taking verapamil, and pedal edema and transient flushing in 2 patients each using diltiazem. Thus, high-dose verapamil and diltiazem have similar beneficial effects and are safe for the long-term treatment of effort-related angina pectoris.

Angina Pectoris↗
PubMed1984

Prognostic importance of a clinical profile and exercise test in medically treated patients with coronary artery disease.

To identify predictors of mortality in medically treated patients with symptomatic coronary artery disease, 30 variables were analyzed in 4,083 patients. Regression analysis demonstrated that seven variables were independent predictors of survival. A high risk subgroup (annual mortality rate above 5%) was identified, consisting of patients with either a congestive heart failure score of 3 to 4 or 1 mm or greater ST segment depression and final exercise stage of 1 or less. When all 30 variables were analyzed conjointly, the left ventricular contraction pattern (p less than 0.0001) and the number of diseased coronary vessels (p less than 0.003) proved to be the most important predictors of survival. In a subgroup of 572 patients with three vessel coronary disease and preserved left ventricular function, the probability of survival at 4 years ranged from 53% for patients only able to achieve stage 1/2 of exercise to 100% for patients able to exercise into stage 5 (p less than 0.004). Thus, in patients with defined coronary pathoanatomy, clinical and exercise variables primarily relating to the functional state of the left ventricle are helpful in assessing prognosis.

Adult↗
PubMed1984

Plasma verapamil levels and exercise performance.

Our study in 10 patients with stable, exercise-related angina under a double-blind, placebo-controlled protocol correlated plasma verapamil levels after single oral doses of 120 and 240 mg and exercise performance. Plasma verapamil levels peaked at 2 hr in seven patients and 4 hr in three patients and declined thereafter, with a mean plasma t1/2 of 3.22 and 4.54 hr after the 120- and 240-mg dose. Despite the relatively short t1/2s, total exercise duration and time to onset of angina and S-T segment depression were longer than placebo values for 4 hr after the 120-mg dose and for 8 hr after the 240-mg dose. Percentage increase in treadmill time and log of plasma verapamil levels correlated. All patients with plasma levels above 100 ng/ml had at least a 50% increase in exercise duration. Thus measurement of plasma verapamil levels are useful in patients who fail to respond to a dose of verapamil. If the level is below 100 ng/ml, increasing the dose of verapamil may improve response.

Administration, Oral↗
PubMed1984

The value of preoperative exercise testing in predicting long-term survival in patients undergoing aortocoronary bypass surgery.

To determine whether preoperative exercise testing adds important independent prognostic information in patients undergoing coronary bypass surgery, 35 variables were analyzed in 1241 patients enrolled in the Coronary Artery Surgery Study registry. All patients underwent a treadmill exercise test before bypass surgery and were followed for up to 7 years. Survival in this surgical cohort was 90.6% (1124 of 1241). Multivariate stepwise dicriminant analysis identified the left ventricular score and the final exercise stage achieved as the two most important (p less than .001) independent predictors of postoperative survival. In a subgroup of 416 patients with three-vessel coronary disease and preserved left ventricular function, the probability of postoperative survival at 7 years ranged from 95% for those patients able to exercise to stage 4 to 83% for those whose ability was limited to stage 1 of exercise. Thus, the preoperative exercise test, by assessing the functional capacity of the cardiovascular system, is an important independent predictor of postoperative survival.

Coronary Angiography↗
PubMed1983

Efficacy and safety of verapamil in patients with angina pectoris after 1 year of continuous, high-dose therapy.

The long-term efficacy and safety of high-dose verapamil therapy (480 mg/day) was assessed in 26 patients with chronic stable angina pectoris during a 3-phase protocol: Phase 1--an initial, 6-week placebo-controlled, double-blind crossover assessment; Phase 2--an open label, 1-year follow-up; and Phase 3--a final drug withdrawal and rechallenge 10-week study. Three patients withdrew during Phase 2 (1 had hepatitis and 2 underwent coronary bypass surgery). Adverse effects during Phase 2 were mild, consisting of constipation (6 patients) and prolongation of the P-R interval (5 patients); however, no patient required alteration of the 480 mg/day dosage. At the end of Phase 2, 10 patients underwent the Phase 3 study, commencing with a 2-week period in which verapamil was either tapered gradually or abruptly discontinued. This was followed by an 8-week double-blind, placebo-controlled crossover rechallenge study with verapamil. The clinical and exercise responses to verapamil compared with placebo were similar during the Phase 3 protocol and the initial Phase 1 study (treadmill time increased by 55% and anginal attacks per week decreased by 63% during Phase 3, compared with a 28% increase and a 42% decrease, respectively, during Phase 1, p = not significant [NS]). Withdrawal of verapamil produced a similar return of anginal symptoms whether the drug was abruptly discontinued or its administration tapered. No patient had unstable angina pectoris or acute myocardial infarction. These investigations demonstrate that verapamil is safe and effective when evaluated after 1 year of continuous therapy using a dosage of 480 mg/day. There is no evidence of drug tachyphylaxis, nor does verapamil appear to cause an abrupt withdrawal syndrome in patients with chronic stable angina pectoris.

Adult↗
PubMed1983

Cardiokymography during exercise testing: a new device for the detection of coronary artery disease and left ventricular wall motion abnormalities.

The cardiokymograph (CKG) is a device that has been shown to reflect left ventricular (LV) wall motion abnormalities. Its accuracy in detecting coronary artery disease (CAD) during treadmill exercise testing was assessed in 204 consecutive patients undergoing coronary arteriography. Of the 188 patients with a technically adequate CKG, 146 (78%) had significant CAD. The sensitivity and specificity were similar for both the exercise electrocardiogram (ECG) (66% and 86%, respectively) and the exercise CKG (73% and 95%, respectively). An abnormal exercise CKG was significantly more common in patients with 3-vessel CAD than in those with 1-vessel disease (97% versus 52%, respectively; p less than 0.001) and in patients with left anterior descending disease than in those without (85% versus 26%, respectively; p less than 0.001). Seventy patients showed both an abnormal exercise ECG and CKG; all had CAD and 86% had multivessel CAD. Forty-eight patients demonstrated a normal exercise ECG and CKG; 29% had CAD but only 6% had multivessel CAD. Among 55 patients who had simultaneous exercise radionuclide ventriculography, new septal or apical wall motion abnormalities were found in 79% (23 of 29) of patients with an abnormal CKG compared with 19% (5 of 26) of patients with a normal CKG (p less than 0.001). Thus, the CKG during exercise testing accurately reflects LV wall motion abnormalities and can be used to improve the diagnostic accuracy of exercise testing as an additional marker of myocardial ischemia.

Adult↗
PubMed1983

Prognostic assessment of patients with coronary artery disease by exercise testing.

To assess whether exercise testing could help predict cardiac mortality, we analyzed 14 exercise and 10 clinical variables in 292 patients treated medically, who underwent treadmill exercise testing and cardiac catheterization and were followed annually for a mean of 2.5 years. None of the individual variables could accurately predict subsequent cardiac mortality with predictive values ranging from 6% to 44%. Combinations of variables were then analyzed in the subset of 113 patients with multivessel coronary disease. A high-risk subgroup (n = 59) consisting of patients with either severe exercise ischemia (greater than or equal to 2 mm ST depression lasting greater than or equal to 5 minutes involving greater than or equal to 3 leads) or left ventricular dysfunction (treadmill time less than or equal to 3 minutes, S3 gallop, or cardiac enlargement) had a mortality of 20%; this was significantly greater (p less than 0.01) than a low-risk subgroup (n = 54) with neither severe exercise ischemia nor left ventricular dysfunction whose mortality was 2%. We conclude that combining clinical and exercise variables to distinguish high- and low-risk subgroups of patients with similar coronary anatomy is useful in predicting cardiac mortality.

Adult↗
PubMed1983

Efficacy and safety of incremental doses of diltiazem for the treatment of stable angina pectoris.

The safety and efficacy of incremental doses of diltiazem in treating angina pectoris were assessed in 20 patients with functional class II to III exertional angina. During an initial single-blind dose titration phase, dilitiazem produced a dose-related improvement in anginal frequency and exercise capacity. Weekly anginal attacks were reduced to 7.5 +/- 8.9, 5.6 +/- 7.8 and 4.9 +/- 7.3 on diltiazem, 120, 240 and 360 mg per day, respectively, as compared with 11.9 +/- 8.7 on placebo (all p less than 0.001). Treadmill time was significantly enhanced by high dose (360 mg per day) as compared with moderate dose (240 mg per day) diltiazem: 473 +/- 149 versus 424 +/- 146 seconds (p less than 0.05). Time to ischemic ST segment depression was similarly changed: 344 +/- 132 versus 298 +/- 142 seconds (p less than 0.05) by high dose as compared with moderate dose diltiazem. During a subsequent double-blind phase, high dose diltiazem significantly reduced weekly anginal frequency when compared with placebo: 3.1 +/- 3.0 versus 9.3 +/- 7.1 (p less than 0.001); and increased treadmill exercise time: 508 +/- 158 versus 418 +/- 172 seconds on placebo (p less than 0.05). Subjective and objective benefits of high dose diltiazem were sustained during a follow-up period of 6 months without major drug side effects.

Adult↗
PubMed1982

Determinants of clinical response and survival in patients with congestive heart failure treated with captopril.

The efficacy of chronic ambulatory captopril (CPT) therapy was evaluated over an 18-month period in 36 patients with refractory chronic congestive heart failure (CHF) by cardiac catheterization, treadmill exercise, nuclear scintigraphy, echocardiography, and symptomatology. Clinical improvement to New York Heart Association functional class I or class II was observed in 63% of the patients (20 of 32) after 2 months of treatment; this amelioration of CHF symptoms was sustained in 63% of the patients (10 of 16) at 18 months. Exercise tolerance increased in 64% of the patients (16 of 25) at early follow-up and in 79% (11 of 14) at late follow-up. Univariate analysis revealed that the pre- and post-CPT stroke work indices (SWI) and the post-CPT cardiac index related to favorable long-term clinical response. Fourteen CHF patients (39%) died during the 18-month follow-up. Univariate analysis revealed that the pretreatment SWI, right atrial pressure, plasma norepinephrine concentration, and echocardiographic shortening fraction were significant predictors of mortality. Multivariate analysis indicated that the SWI was the principal determinant of survival: the 18-month cumulative survival rate for CHF patients with a SWI less than 32 gm . m/m2 was 44% compared to 88% when the SWI was greater than 32 gm . m/m2. Thus, CPT results in sustained symptomatic and functional improvements in patients with advanced CHF, but the mortality remains high and is primarily related to the severity of cardiac dysfunction.

Acute Kidney Injury↗
PubMed1982

Prognostic significance of angiographically documented left ventricular aneurysm from the Coronary Artery Surgery Study (CASS).

In order to evaluate the prognosis of medically treated patients with angiographically defined left ventricular aneurysm the data available from 1,136 patients with aneurysm (7.6 percent) from 15,019 patients with coronary artery disease in the Coronary Artery Surgery Study (CASS) registry were analyzed. Prior myocardial infarction, reduced ejection fraction, absence of angina and evidence of congestive heart failure were more commonly present in patients with aneurysm. The cumulative survival rates of medically treated patients at 1, 2, 3 and 4 years were 90, 84, 79 and 71 percent, respectively. The Cox analysis of survival indicated that the following variables predicted outcome: age, residual left ventricular function as assessed with angiography, left ventricular end-diastolic pressure, functional impairment due to congestive heart failure, number of vessels diseased, mitral regurgitation and S3 gallop. When survival was stratified for similar degrees of left ventricular dysfunction and functional impairment there was no difference between the survival of patients with aneurysm and that of registry patients without aneurysm. The data from this large population study indicate that the survival of patients with left ventricular aneurysm is better than previously recognized. The mortality in this group is primarily related to age, left ventricular function and clinical severity of heart failure. The presence of an aneurysm does not independently alter survival.

Coronary Angiography↗
PubMed1982

Decrease in systolic blood pressure during exercise testing: reproducibility, response to coronary bypass surgery and prognostic significance.

To investigate the reproducibility and prognostic significance of an exercise-induced decrease in systolic blood pressure, 47 patients were identified who manifested such a reduction below the pre-exercise standing level in a consecutive series of 436 patients who underwent treadmill exercise testing and cardiac catheterization during a 3 year period. The prevalence of this abnormal finding was 11 percent in the total group but 21 percent in the 124 patients with three vessel or left main coronary artery disease. Patients with an exercise-induced reduction in systolic blood pressure were more likely to be male, have typical angina pectoris with class III or IV functional limitation and to have had a prior myocardial infarction than were patients without this finding (p less than 0.05). Although no complications occurred during the exercise test of these 47 patients, the majority had severe ischemic responses and 14 (30 percent) showed complex repetitive ventricular arrhythmias. Of the 47 patients, 24 (group 1a) received medical treatment and 23 (group 1b) underwent coronary bypass surgery. On repeat exercise testing in 42 patients, a decrease in systolic blood pressure during exercise was consistently present in group 1a (17 of 20) but entirely absent (0 of 22) in group 1b (p less than 0.001). The mean treadmill time, peak heart rate and systolic blood pressure were not significantly different in the initial and on repeat exercise tests in patients in group 1a; however, in patients in group 1b, all of these variables were significantly higher in the repeat test (p less than 0.001). At a mean follow-up time of 37 months, the total cardiac mortality rate was 8 percent (2 of 24) in group 1a and 4 percent (1 of 23) in group 1b. It is concluded that a decrease in systolic blood pressure during exercise testing is highly reproducible and appears to be reversed by coronary bypass surgery.

Angina Pectoris↗
PubMed1982

Therapeutic and economic value of a normal coronary angiogram.

A significant number of patients with severe angina or intractable atypical chest pain referred for coronary arteriography are found to have normal coronary vessels. To determine what therapeutic or economic benefit may be derived from these studies, we analyzed the data of 72 consecutive patients with normal vessels referred for cardiac catheterization because of severe chest pain. The clinical status and hospitalizations were analyzed for the 2 year period before and the 2 year period after angiography. There were no deaths or myocardial infarctions. Although 47 were thought to have angina and 25 atypical pain before catheterization, the chest pain was reclassified with only 15 continuing to have anginal pain, 40 atypical pain, and 17 no pain. Functional improvement by at least one New York Heart Association class occurred in 74 percent of patients with 36 (50 percent) having no functional limitation. The use of cardiac medications was also significantly reduced. Despite functional improvement, no change in employment states could be demonstrated. The use of medical facilities was significantly less, the average number of hospital days per patient declining from 17 to 3.9 and hospitalization decreasing from 1.5 to 0.4. The result was a significant decrease in estimated hospital costs. We conclude that in patients referred for coronary angiography for severe chest pain, documentation of a normal coronary arteriogram significantly alters the clinical assessment of symptoms, improves functional status, modifies medical therapy, and reduces hospitalization and medical costs. These therapeutic and economic benefits deserve consideration in the evaluation of coronary angiography for its overall effectiveness.

Adult↗