Left Ventricular Function After Cigarette Smoking by Chronic Smokers: Comparison of Normal Subjects and Patients With Coronary Artery Disease

ABNASH C. JAIN, MD, FACC ALLEN F. BOWYER, MD ROBERT J. MARSHALL, MD, FACC HIROAKI ASATO, MD

Morgantown, West Virginia

Twenty normal subjects and 25 patients with coronary artery disease underwent syslolic time interval analysis before and after rapidly smoking two cigarettes. A slight Increase in heart rate and arterial pressure was seen in both groups. In patients with coronary artery disease, preejection period/left ventricular ejection time ratio Increased; in normal subjects it decreased. Left ventricular performance Is diminished after cigarette smoking among subjects who have preexisting significant coronary artery disease.

The effects of long-term smoking include the risk of developing coronary artery disease and myocardial infarction. 1 In addition to this chronic effect, a direct acute myocardial depressant effect of smoking has been suggested. 2 The hemodynamic effects of cigarette smoking in long-term smokers suggest that smoking causes myocardial stimulation with increased heart rate, arterial pressure and cardiac output. 3-5 Noninvasive systolic time interval measurements in subjects without coronary artery disease have shown a reduction of external isovolumetric contraction time. 6 This finding, too, suggests myocardial stimulation rather than depression. The effects of cigarette smoking on left ventricular systolic time intervals have not previously been documented in subjects with coronary artery disease. The purpose of this study was to provide such documentation and to compare smoking-induced systolic time interval changes in subjects with and without angiographically documented coronary artery disease. We used noninvasive systolic time interval analysis for evaluation of left ventricular function to avoid any hemodynamic alteration induced by invasive procedures. The coronary circulation was evaluated with resting and exercise electrocardiography, selective coronary arteriography and left ventricular angiography. No normal subject had evidence of coronary artery disease by angiography. All patients with coronary artery disease had abnormal exercise electrocardiograms and coronary arterial stenosis of more than 70 percent of luminal diameter in one or more vessels. Material and Methods

From the Divisionof Cardiology, West Virginia University School of Medicineand West Virginia University Medical Center, Morgantown, W. Va. Manuscript received March 19, 1976; revised manuscript received July 6, 1976, accepted July 7, 1976. Addressfor reprints: Abnash C. Jain, MD, Division of Cardiology, West Virginia University Medical Center, Morgantown, W. Va. 26506.

The study population consisted of 45 male long-term smokers who had had diagnostic coronary arteriography for evaluation of chest pain. All had smoked 1 to 2 packs of cigarettes/day for not less than 5 years. Twenty were classified as normal on the basis of lack of effort-related chest discomfort and normal resting electrocardiogram, exercise electrocardiogram, ventricular angiogram and coronary arteriograms. Twenty-five had symptomatic coronary artery disease. All had typical effort-related chest discomfort, abnormal exercise stress electrocardiogram and normal left ventricular angiogram,but abnormal coronary arteriograms (Table I). All tests were interpreted by three observers independently as well as collectively to provide consistency and uniformity of reading. The age range of the normal group was 35 to 51 years (mean 46). These ages were

January 1977 The AmericanJournalof CARDIOLOGY Volume39

27

LEFT VENTRICULAR FUNCTION AFTER CIGARI=TII: SMOKING---JAIN ET AL.

not significantly different from ages in the group with coronary artery disease (P > 0.05). All studies were performed with the subject supine 2 hours after a meal and after he had abstained from smoking for 4 or more hours. After control measurements of heart rate, blood pressure and systolic time intervals, the subject smoked, in-

TABLE I Coronary Arteriographic Findings in Normal Subjects and Patients With Coronary Artery Disease

Group Normal subjects Patients with coronary artery disease

no. of Cases

Age (yr) Mean and Range

Coronary Arteriography

20

46; 35--51

No lesions

25

47; 38--56

>70% stenosis 1 vessel (2) 2 vessels (15) 3 vessels (8)

Figures in parentheses indicate number o f patients.

haling deeply, two cigarettesof a c o m m o n commercial brand containing 20 m g of nicotine. The measurements were repeated 5 minutes after smoking. Systolic time intervals were measured from simultaneous electrocardiogran~ carotid pulse tracing and high frequency phonocardiogram recorded at 100 mm/sec using a multichannel apparatus (Elema Mingograph). Careful attention was given to (1) recording the onset of ventricular depolarization,(2) obtaining a clear,well defined carotidupstroke and incisura, and (3) identifying the initialhigh frequency component of aortic valve closure (Fig. 1). Total electromechanical systole (QS2) was measured from the onset of ventricular depolarization in the electrocardiogram to the initial high frequency portion of the aortic component of the second heart sound. Left ventricular ejection time was measured from the beginning of the upstroke of the carotid pulse tracing to the incisura. The $1-$2 interval was measured between the initial high frequency components of the first and second heart sounds. Subtraction of left ventricular ejection time from $1-$2 gave the external isovolumetric contraction time. The ratios of preejection period to left ventricular ejection time and of left ventricular ejection

TABLE II Group Means and Differences for Heart Rate, Brachial Pressures and Systolic Time Intervals in 20 Normal Subjects and 25 Patients With Coronary Artery Disease (mean values +- standard error). Coronary Artery Disease

Normal

28

Difference Between Groups

t

P

Heart rate (beats/rain)

Control Smoking Change t P

73.80 + - 2.16 80.90 +- 2.23 +7.10 -+ 0.41 17,236

Left ventricular function after cigarette smoking by chronic smokers: comparison of normal subjects and patients with coronary artery disease.

Left Ventricular Function After Cigarette Smoking by Chronic Smokers: Comparison of Normal Subjects and Patients With Coronary Artery Disease ABNASH...
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