Sildenafil's Effectiveness in the Primary Coronary Slow Flow Phenomenon: A Randomized Controlled Clinical Trial

BackgroundOn the one hand, the coronary slow flow phenomenon (CSFP) may cause recurrence of chest pain, prompting medical examinations and further healthcare expenses, and on the other side, it can result in myocardial infarction, ventricular arrhythmia, and sudden cardiac death. ObjectivesDue to the lack of agreement on the optimal treatment for CSFP, we decided to examine the effectiveness of sildenafil in this context. MethodsWe assessed the eligibility of 196 CSFP patients to participate in a 12-week, triple-blind, randomized, placebo-controlled study for receiving either 50 mg daily oral sildenafil or placebo. We evaluated the efficacy of sildenafil based on exercise tolerance test parameters, severity of angina, adverse effects, and major adverse cardiovascular events. ResultsTwenty eligible patients were randomly allocated in a 1:1 ratio to two groups. Sildenafil demonstrated significant efficacy in improving angina severity, with all recipients achieving a Class I angina severity, contrasting with a 40% attainment in the placebo group (P=0.011). Notably, Sildenafil induced statistically significant reductions in systolic and diastolic blood pressure, unlike the placebo group. Although a reduction in the QT interval favored Sildenafil (-21 millisecond vs +3 milliseconds), statistical significance was not reached (P=0.09 vs. P=0.67). Moreover, Sildenafil markedly improved Duke Treadmill Score (DTS) (P=0.005), while the placebo group showed non-significant improvement. Concurrently, the Sildenafil group exhibited significant enhancements in functional capacity (METs) and maximum heart rate during exercise testing compared to the placebo group. ConclusionsWe suggest that a daily low dose of sildenafil could be a valuable therapeutic option for CSFP. Graphical abstract O_FIG O_LINKSMALLFIG WIDTH=200 HEIGHT=128 SRC="FIGDIR/small/24301510v1_ufig1.gif" ALT="Figure 1"> View larger version (28K): org.highwire.dtl.DTLVardef@168d767org.highwire.dtl.DTLVardef@15d806org.highwire.dtl.DTLVardef@19846corg.highwire.dtl.DTLVardef@144d9c9_HPS_FORMAT_FIGEXP M_FIG C_FIG