Angina Pectoris and Ambulatory Myocardial Ischaemia in the General Population

Gandhi, Manish M (1994) Angina Pectoris and Ambulatory Myocardial Ischaemia in the General Population. MD thesis, University of Glasgow.

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Abstract

Since the original population study of angina pectoris which commenced in Framingham in 1949, there has been no contemporary study of this common disease in relation to incidence, clinical characteristic and prognosis. The overall objective of this study was to investigate new cases of angina in the population presenting for the first time with this symptom of coronary disease. Specifically the objectives were to measure the clinical incidence of angina and to assess the patients' clinical characteristics with particular reference to ambulatory and exercise electrocardiography and the relationship of these physiological variables to prognosis. A random sample of 17 general practices was drawn from within the boundary of the city of Southampton and all 117 general practitioners agreed to refer every new patient ? 70 years with no previous CHD presenting for the first time with suspected angina to an open access chest pain service. Of 110 consecutive patients presenting with typical angina, 70 were male and 40 female. The crude annual incidence rate (95 % confidence interval) of angina pectoris in this representative population sample was 0.83 (0.66, 1.0) per thousand population aged 31-70 years; for men and women the rates were 1.13 (0.85, 1.40) and 0.53 (0.33, 0.72) respectively. The incidence of angina pectoris in the United Kingdom is estimated from this study to be at least 22,6(X) patients per annum. Ninety-six of 110 angina patients and 95 age, sex and practice matched asymptomatic healthy controls underwent 24 hour ambulatory ECG monitoring prior to antianginal therapy. All tapes were analysed blind. Ischaemic ST segment depression, defined as ≥ 1mm horizontal/downsloping shift from baseline at J-l-80 msec lasting > 1 min, was prevalent in 34 of 64 (53%) men with angina vs 7 of 59 (12%) male controls, and in 16 of 32 (50%) women with angina vs 2 of 36 (6%) controls. In logistic regression analysis, serum cholesterol (p = 0.02) and exercise ischaemia (p = 0.003) were independently associated with the presence of ambulatory ischaemia in men with angina, but only the latter was significant in women; this may reflect a different pathophysiological basis for ambulatory ischaemia in women. At a median follow-up of 15.8 (range 7-30) months, angina remitted spontaneously in 12 (11%) patients, 20 (18%) patients underwent revascularisation, 8 (8%) sustained a non-fatal myocardial infarction, and 4 (4%) died. In Kaplan-Meier survival analysis, there was no significant difference in event-free survival from coronary angioplasty, coronary artery bypass grafting, myocardial infarction or death between patients with and without ambulatory ischaemia (66% vs 72%, p=NS). This is the first contemporary population study of new patients with angina pectoris since the advent of widespread non invasive electrocardiographic assessment, coronary arteriography and revascularisation. Angina is common and while in the majority of patients the resting electrocardiogram is normal at presentation, exercise induced ischaemia (≥1mm) is found in 64% (42 of 66) of men and in 57% (21 of 37) of women. Ambulatory ischaemia is present in over half of new patients presenting with angina, but appears to be of no prognostic value. The prognosis of incident angina despite appropriate cardiological assessment and management is not benign. The study thus raises an important question which should be answered by a randomised controlled trial - does early cardiological assessment and coronary revascularisation reduce the morbidity and mortality of incident angina pectoris?

Item Type: Thesis (MD)
Qualification Level: Doctoral
Additional Information: Adviser: David Wood
Keywords: Medicine, Epidemiology
Date of Award: 1994
Depositing User: Enlighten Team
Unique ID: glathesis:1994-75660
Copyright: Copyright of this thesis is held by the author.
Date Deposited: 19 Nov 2019 18:59
Last Modified: 19 Nov 2019 18:59
URI: http://theses.gla.ac.uk/id/eprint/75660

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