What exactly is congestive heart failure and why does it occur?
This is a chronic condition in which the heart does not pump blood as well as it should. Heart failure can occur if the heart cannot pump (systolic) or fill (diastolic) adequately. Congestive heart failure carries a high morbidity and mortality, especially when associated with left ventricular dysfunction. However, making the diagnosis poses some difficulty, especially for general practitioners (GPs) who are often the first to see the patients. Erroneous diagnosis is made in more than 40% of cases, leading to wrong treatment. Diagnosis in the community is usually based on clinical assessment and chest radiograph, the sensitivity of which has been put at 92%.
Congestive heart failure (CHF) is said to increase the risk of sudden cardiac death. How can such death be avoided or reduced in Nigeria?
Persons with acute heart failure, once picked and properly managed, will do well. However, those with acute decompensated or advanced heart failure with poor systolic function can die any moment due to complications. The one-year death rate from heart failure is as high as 50%, especially in the elderly. The five-year death rate approaches 70%. Good and adequate contemporary management reduces the mortality rate, especially when modern drug therapy combined with heart-assisted devices is employed. Abnormal heart rhythm and conduction abnormalities should be treated, and clots within the heart chambers prevented.
Above all, adequate rest is perfect for heart failure cases. Prevention of heart failure by taking care of possible causes and, of course, the precipitants or risk factors should be pursued adequately.
Beyond clinical examination, what diagnostic tools are available for heart failure
Echocardiogram (Echo) has been introduced to improve the diagnosis and management of CHF. However, considering the economic cost of this latest cardiologic tool, it may be out of reach for most patients. Also, its availability in most referral centres cannot be guaranteed. Hence, a case is being made for the greater use of the simple electrocardiogram (ECG) as an adjunct to clinical assessment and chest radiograph before referral to a cardiology centre for more definite management.
The combination of these clinical tools has been shown to have 100% sensitivity and 95% specificity. This approach is cost-effective and reduces the considerable cost of echocardiogram. We also advocate more purposeful ECG training for all resident doctors, especially GPs, in identifying simple ECG abnormalities.
From your experience, how effective is ECG in detecting congestive heart failure among patients?
I and some physicians in one of our teaching hospitals in Nigeria looked at the usefulness of this tool in making the diagnosis of heart failure in Nigerians. Two hundred and seven patients referred to our unit by general practitioners for cardiology evaluation for congestive cardiac failure were studied. The patients were critically examined clinically for signs of heart failure after a detailed history.
They were divided into two groups, namely: those with clinical evidence of heart failure (Group A) and those without evidence of heart failure (Group B). Group B cases served as control. Both groups were then exposed to chest X-ray and 12-lead electrocardiogram to detect abnormalities. The ECG tracings were read by the same cardiologist. Echocardiogram was then carried out on those with abnormal clinical assessment, whose ECGs were abnormal, and who had suffered CHF with poor cardiac function, as evidenced by the left ventricular ejection fraction, fractional shortening, and chamber diameters.
A total of 207 patients were studied. All Group A patients had chest radiographic and echocardiographic findings consistent with poor cardiac function, while Group B patients had enlarged cardiac shadows and ECG findings but with good cardiac function. It was observed that once there is cardiac damage, the ECG becomes abnormal. Major abnormalities observed in this study enhance the diagnosis of heart failure, especially when combined with the patient’s complaints, the physician’s findings, and chest X-ray results.
What key findings or conclusions emerged from your study?
This study shows that the electrocardiogram (ECG), though an old cardiologic tool, still plays a significant role in the initial assessment, diagnosis, and subsequent management of congestive heart failure (CHF). The diagnosis of heart failure depends on clinical features in terms of symptoms, signs, and evidence of underlying cardiac pathology.
However, clinical features are insensitive, lack specificity, and are often irreproducible, especially in elderly patients. A combination of clinical features and chest radiograph has been found to improve the diagnosis. Additionally, the triad of detailed clinical examination, chest radiographic abnormality, and major ECG abnormality has been found to enhance the diagnosis of CHF with higher sensitivity, specificity, and predictive values.
The fact that ECG lacks specificity (with specificity of 10% obtained in this study), coupled with its inability to make structural diagnosis or differentiate between systolic and diastolic cardiac dysfunction, makes echocardiogram a more superior tool. Hence, ECG is not a substitute for echocardiogram, but it remains a less expensive, simple, and cost-effective tool that is useful in the initial evaluation of patients.
Premature atrial contraction (PAC) was considered a major ECG abnormality in the study because it was previously discovered as a major arrhythmia in adult Nigerians with hypertensive heart disease. Hypertensive heart failure (HHF) constituted the bulk of patients with CHF in this study and, of course, remains the commonest cause of heart failure in adult Nigerians.
What do these findings reveal about managing heart failure in Nigeria?
Even though atrial fibrillation (AF) is a major ECG abnormality, its prevalence is low in Nigeria. It is a fact that the consensus among cardiac specialists is the use of echocardiogram for all CHF patients. However, not every patient can afford the cost of this expensive tool, and not many centres have echocardiographic facilities. Hence, a very good and detailed clinical assessment, combined with abnormalities on chest radiograph and major ECG abnormalities, is diagnostic and sensitive.
The presence of a cardiac murmur calls for cardiology review. Simple ECG interpretation should not be left to cardiologists alone. Adequate and purposeful exposure of resident doctors, especially GPs, to ECG should be encouraged. Equipping our laboratories with facilities to assay serum atrial and brain natriuretic peptides (ANP and BNP), which are elevated in congestive heart failure, coupled with ECG and chest X-ray, will reinforce the diagnosis of CHF and help select those who will need echocardiogram.
In conclusion, the ECG is a valuable first-line tool in the investigation and analysis of CHF in developing countries with depressed economies. This is attested to by the high sensitivity result obtained in this study. A normal ECG definitely excludes CHF. However, an abnormal ECG does not confirm congestive heart failure (CHF) but depicts an underlying cardiac pathology that can be further assessed echocardiographically.
The combination of chest X-ray and ECG in a well-clinically assessed patient increases the diagnostic yield of CHF. The presence of a cardiac murmur and/or increased serum ANP/BNP in a patient with normal or abnormal chest X-ray and ECG calls for echocardiogram.
Finally, what is your advice to both doctors and patients?
There are many tools used by physicians to assess damage to the heart before eventual heart failure. One of the oldest tools is the electrocardiogram. The study mentioned above examined the usefulness of this tool in diagnosing heart failure in Nigerians. It was observed that once there is cardiac damage, the ECG becomes abnormal. Major abnormalities observed in this study enhance the diagnosis of heart failure, especially when combined with the patient’s complaints, the physician’s findings, and chest X-ray results.
People should be patient with their doctors when they are advised to carry out some or all of these tests. They help the doctor make an accurate and timely diagnosis. Even though there are many tools used by physicians to assess heart damage before heart failure, one of the oldest is the electrocardiogram. Its importance and relevance cannot be overemphasized. Therefore, people should be patient with their doctors when asked to undergo tests that aid in making a reasonable diagnosis.